Popular Prospecting 1955

Popular Prospecting

A Field Guide for the Part"time Prospector INCLUDES DATA FOR THE GEM HUNTER, URANIUM SEEKER, and the PROSPECTOR

FOR STRATEGIC METALLIC and NON-METALLIC MINERALS.

By

H. C. DAKE Editor -

THE :MINERALOGIST

MAGAZI~E

FIRST EDITION -1955

Price $2.00

Copyright 1955

By The

Mineralogist Publishing Componr 329 S.E. 32nd Avenue

Portland IS, Oregon

r

Books for Prospectors, Uranium Hunters,

Gem Cutters and Collectors

THE FOLLOWING BOOKS will be found useful for data in related fields of interest. For the convenience of the reader these books are available from most supply firms, book sellers and journals in this field, or may be had direct from THE MINERALOGIST, 329 S. E. 32nd Avenue, Portland 15, Oregon.

ARIZONA GEM TRAILS -

By Ransom. New guide book, for gem hunters and mineral collectors. Describes many localities in Arizona, including new and little known regions, where valuable gems and minerals are available. \Vritten by one who has been there. Includes data on uranium in Arizona. Tours and localities described in detail. Price $2.00.

HANDBOOK URANIUM MINERALS- New issue. Intended for the uranium pros­ pector, and collector of fluorescent gems and minerals. Describes in detail, use of Geiger counter, formations in which uranium is likely to occur, localities through­ out the United States, and the world. Describes in detail all the important com­ :dercial uranium minerals. The "bible" for the uranium prospector. Combined in one volume, is a complete listing of all known fluorescent gems and minerals. Describes a!! popular ultra-violet lamps used, filters, and equipment. Price $2.00.

THE AGATE BOOK -

For t4e agate hunter, cutter and collector. Describes in de­ tail all varieties and sub-varieties of agate. The first complete book on agate, with 50 photos, showing numerous types of agate, localities where found included. By H. C. Dake. Price $2.00.

NORTHWEST GEM TRAILS -

Describes hundreds of localities in Oregon, Wash­ ington, Idaho, Montana, and Wyoming. Illustrated with maps and photos. For the gem hunter and mineral collector. Only book of its kind ... Price $2.00.

ART OF GEM CUTTING -

By Dake, (Complete) new 5th edition, 128 pages . . . Completely illustrated showing all types modern gem cutting equipment. Most complete work ever written on modern met!lOds of gem cutting, specimen finish­ ing, cabochon and facet cutting. Includes sections on gem identification, use in­ struments, special lapidary technic, and other helpful information, for the begin­ ner, and the advanced technician. Price $2.00.

CALIFORNIA GEM TRAILS -

New enlarged and revised second edition. Describes in detail, gem and mineral localities throughout the state. 'With detail maps and photos. Price $2.00.

GUIDE TO ROCKS AND MINERALS -

By Pough. The ideal book for beginners, as well as the more advanced. Aids in the identification of minerals and rocks. There is none better. Illustrated with' 254 fine photos, with 72 in full color. Price $3.75.

THE MINERALOGIST MAGAZINE -

Since 1933, this monthly (except July and August) magazine has pioneered in featuring articles of general interest in the field of fluorescent gem and minerals, and the uranium minerals. Features are also printed for the gem cutter, many localities throughout the United States are described. Subscription $2.00 per year, for ten issues. The Mineralogist Publish­ ing Company, 329 S.E. 321ld Avenue, Portland 15, Oregon.

Tile Mineralogist Magazine [Book Department]

329 S. E. 32nd AVENUE

..

PORTLAND 15, OREGON

Contents

Page FOREWORD ............._..._........_......_........._._ ....__.._..................... , .................... _. __ .__ . 4

CHAPTER

I

WHERE TO PROSPECT .._._. _____ ..._....... _....._...._...___ .___ .____ ._______ .__.__ .___

7

Occurrence of Ores ...._....______ ._____ .._.._..__~. ____ ._ ... __ ._ ......................_....___ ..

7

Gem Stone Placers ...__ ._.... _......_..................... ,...._............................_..... 13

Lode Deposits ........_.................................... _......................................... 15

II

THE GEM MINERALS ....................................................................... 19

The Jade Fields ...................................................................................... 24

III

THE METALLIC MINERALS ...................................................._..._ 29

Chromium ........................................_..............................____ ................._.. 29

Lead ........................................................._.._.._.......................................... 30

Mercury .................................................................................................... 31

Rare Earth Metals ....._...._...._..............._.....................____ ........... """""" 32

Tungsten .................................................................................................. 33

IV THE NON-METALLIC MINERALS ................................._............ 35

Abrasives .................................................................................................. 35

Building Stones .............................. _............._........._.,............................. 36

Phosphate Rock ................. _........_........................................................... 31

V

THE URANIUM MINERALS ............................................._._._._. 39

Gieger Counters, Scintillometers ...................................................... 40

Uranium Hunting _..................,.............................................................. 41

Uranium Minerals ................................................................................., 47

Uranium Dis,coveries .................._......................................................... 52

VI

NOTES ON PROSPECTING .......................................................... 61

Seismic Methods ......................_._ ..__ ._.__ ........_...................................... 62

Metal Detectors ..............._......_......._......_......._...._......_.............. _............. 64

Salting A Min'e .............................._...._......_._ ...._........__ ................ _........... 66

Pegmatite Prospecting .......................................................................... 68

Lost Min.e Fables ................................................................... _..._._._ .. _.. _ 72

Great Diamond Hoax ............................................................................ 74

F

Foreword

DURING THE PAST DECADE the avocation of part time prospecting has developed into a National leisure time oc­ cupation - with profit to many who en­ gage in this pleasant activity. There are a number of reasons for this remarkable development. The demand for certain minerals, which a few decades past were only scientific curiosities, has brought about wide public interest in prospecting. Uranium is a good example. The gevelop­ ment of the jet engine, and various elec­ tronic instruments, has also brought about a wide demand for minerals which pre­ viously had little value and only limited uses in the arts and industries. Previous guides for the prospector have devoted little attention to the possibilities of the gem and ornamental stones. With the recent development of the gem cutting hobby, on a National scale, the demand for gem cutting min­ erals has increased enormously. In the field of non-metallic minerals the scope of possibilities for the prospec­ tor has increased enormously. For ex­ ample, the development of the use of perlite (a variety of obsidian) as a build­ ing material, has brought this previously worthless rock into the money group. The discovery of small amounts of ura­ nium in phosphate rock has changed the status of the possibilities of this old source of fertilizer and chemicals. There are millions of acres of phosphate rock scattered throughout the United States. These deposits are of utmost present and future importance. The development of the H-bomb brought about an added need for lithium minerals, an essential ingre­ dient in this destructive monster. History is replete with many examples of where a prospector searching for and recognizing only one mineral (usually gold) passed by bonanzas. The Comstock Lode of Virginia City, Nevada, is a clas­ sic example. The first party of prospec­ tors, searching for gold, passed by this billion dollar property, when they failed to recognize the heavy black silver min­ erals that cluttered up the sluice boxes. The "richest hill on earth" at Butte, Montana, was at one time considered worthless by prospectors, when the rich surface silver-copper ores were first en­ countered. Many similar instances could be cited, as a matter of historical record. It is obvious that the day of the pros­ pector, searching solely for gold, is gone

forever. The remaining gold pockets that await discovery are few, and the fabu­ lous "lost" mines of fact and fiction are still more elusive. I t will be seen that the modern day prospector will do well to become in­ formed on the appearance and occurrence of various minerals, to enable recogni­ tion in the field. The prospector without this knowledge will be working under a handicap, and will be likely to pass by a valuable deposit solely through lack of knowledge. How may this knowledge be acquired? One of the easiest and most simple ways of becoming familiar with the com­ mon economic minerals is by handling them, noting their color, form, "heft," and general appearance. This is not at all as difficult as it may sound. Every min­ eral, ore, and gem material has certain characteristics, just like every human be­ ing has certain characteristics that may be difficult to describe. However, by seeing and handling typical minerals and ores, we soon become familiar with them, enabling recognition instantly, on For example, "hefting" of a sample a good practice to develop early in the game. The skilled .jade hunter in Wyo­ ming, searching through a maze of com­ mon rocks, all similar in outside appear­ ance, will soon develop skill in "hefting." Jade is about twice as heavy, bulk for bulk, as common rock, hence with a little practice, the valuable jade can be readily sorted from the common rock. This same practice is applicable to any mineral dis­ tinguished by a high specific gravity. Many times we have observed a pros­ pector searching for some mineral, the typical appearance of which he was not familiar. Only blind luck would help here. Few prospectors searching for uranium are familiar with the typical and common uranium minerals other than yellow car­ notite--there are yellow colored minerals other than carnotite. All too often the prospector will waste a lot of time and energy working on a false trail, when an inexpensive set of economic minerals would have put him right to begin with. Sets of this kind are available at a low cost from the many mineral supply houses throughout the country. A little study of these typical ores and minerals will be of great value to any prospector. We might cite the case of the prospec­ tor searching for sapphire in Rock Creek

FOREWORD in Montana. He panned out, among other items, a number of water worn, beautiful­ ly colored, cornflower blue stones. They were without doubt flawless and perfectly colored. He assumed, in fact he insisted, these were valuable sapphires, since they were found in the stream gravels. This was only a natural assumption, ·but not a correct one. A simple test for hardness, using a common file, would have indicated otherwise, and saved the prospector a lot of time and excitement. These fine cornflower blue pebbles were nothing more than water worn glass, from a Bromo Seltzer bottle, cast into the stream by an earlier day prospector who had celebrated his good fortune too well. Judging by color alone may be decep­ tive in many other ways. The yellow of limonite iron may be taken by the unini­ tiated to be carnotite uranium. The dull green color of some iron stains may be mistaken for copper or nickel. The yellow green, or blue stains of uranium, copper, or nickel are never dull in color, but always vividly bright. Once these are seen in a typical sample they will not be forgotten, and will be instantly recog­ nized on sight. No attempt will be made here to enter into the legal aspects of filing mining claims. Laws differ in various states, while most parts of the great Public Do­ main are open to mining entry, other regions, like National Parks and Monu­ ments are closed to mining entry. Infor­ mation relating to filing mining claims on a specific area are available at the County court house, or nearest U.S. Land Office. The U. S. Atomic Energy Com­ mission, field office at Grand Junction, Colorado, has information on the adja­ cent regions where uranium occurs. A mineral discovery made on private prop­ erty can often be shared by arranging with the owners, filing on a 50-50 basis. During the past 100 years, many of the great mineral deposit discoveries have been made by the prospector. In some cases these discoveries were made in a more or less accidental manner, like Kel­ logg's mule in the Coeur d' Alene of Idaho, and the lads building a mill race for Sutter in California. Pure luck, with­ out any knowledge has also revealed some important deposits. But these are the exception rather than the rule, and are not to be depended upon. Before LaBine set out for the wilder­ ness of Northern Canada, he made a study of all the old geological reports avail­ able for this region. LaBine was search-

5

ing for cobalt-silver deposits, popular at that time. He dusted off some old for­ gotten reports, and read of a likely place and set forth with a partner. LaBine found no valuable cobalt deposit, but he did stake out a valuable silver property, and what eventually proved to be the second most fabulous uranium 'deposit in the whole world. He was well reward­ ed for his study and effort. LaBine was familiar with mineralogy, hence he was enabled to recognize a potentially valu­ able mineral outcrop. when he saw one. In prospecting certain areas for some specific mineral, the reports of the U. S. Geological Survey and the state mining bureaus will often prove invaluable. Geo­ logical maps of these regions are also of considerable value. Almost anyone able to walk, and get out into the field may engage in this pleasant part time prospecting. Anyone may make a valuable find, but it is true that those with at least an elementary knowledge of minerals, and some geology will stand a better chance of making a new discovery. The prospector of a few generations past was generally interested only in gold. No mineral knowledge was required to recognize gold nuggets appearing in the pan.If there was any question of their na­ ture it was only necessary to flatten them out on an anvil. History does not record how many very valuable mineral deposits these old timers passed by, but they were numerous. The day of gold "pocket" hunting is almost a thing of the past, and little reference to same will be made here. The large gold dredge properties have long since been taken up. The last "boom" in gold prospecting was during the de­ pression days, when many idle hands took to the hills. Most of them were enabled to wash out anywhere from 50c to $2.00 per day in placer gold-enough to keep one off the relief roll. Weare assured these days will never return. Along with the developments in science and industry, we find new uses for min­ erals and metals previously regarded only as scientific curiosities. Uranium is a typical example. Only a few years ago this metal had only limited use in the field of ceramics, and only a few tons a year were in demand. When the great Uranium deposits of Belgium Congo and Great Bear Lake, Canada, were first worked, the rich uranium ores were treat­ ed to remove only the radium, and then run out on the waste dumps. At present, thorium is in little demand, but it is likely

1

-,1i

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6

POPULAR PROSPECTING

that this element will eventually be in demand for nuclear fission, same as ura­ nium. Along with the developments in new uses for old metals, technical advances enable us to utilize lower grade ores. Ore deposits that are today regarded as too lean for economical exploitation, may to­ morrow be in wide demand. This should be kept in mind by the prospector. Very low grade copper deposits are being worked today, that a few decades past were regarded as worthless. Prior to the invention of cyaniding for gold, any gold deposit funning less than about $50.00 a ton was passed by. Today, practically all the gold mined in the world is derived from ores running at best only a few dol­ lars per ton. One of the chief require­ ments for any low grade mineral deposit is that there must be a large quantity available. This being the case, sooner or later a way will be found to handle the ore in a profitable manner. In the case of vital strategic metals, economy need not be a factor in commer­ cial utilizatiop. If a metal is vital for our economy or for war use, financial aid will become available. There are a number of these mineral needs. Tin is one. Any low grade tin deposit discovery would likely hold considerable potential value, if large enough, regardless of economic factors. During the past war there was a vital and immediate need for suitable quartz crys­ tals for use in electronic instruments. Brazil was practically the only source for

this most vital need. We had transport planes waiting at the mines to fly back the valuable crystals, soon as they were dug. The cost must have been consider­ able. Before a mineral deposit can be of any immediate value, and readily salable there are a number of factors that must be given consideration. These factors in­ clude such items as location of the' de­ posit. This may include nearness to rail or water transportation. Water for use in milling may also be a factor. Transporta­ tion costs are always important. The size and nature of the deposit is also impor­ tant. In general a small but very rich deposit would be of little value, except in the case of uranium where Federal aid becomes available. The nature of the ores, which involves the cost of treatment, is important. The size of the deposit is per­ haps all important. Enormous deposits, situated even in remote parts of the world, may be feasible for commercial development. The fabulous iron deposits of Labrador, known for many years, are a good example. Many millions of dollars were spent here for development work and transportation, before a ton of ore was shipped. In short, you find a suitable deposit, science will find the way for commercial utilization. H. C. DAKE 329 S. E. 321ld Avenue Portland IS, Oregon February 1955

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CHAPTER ONE

Where To Prospect f'

ri

In answer to the question of where to prospect, the answer can well be, any­ where, for it has long since been learned that no part of the world is wholly devoid of mineral wealth. Even the forbidding desert and arctic regions have been prov­ en to produce fabulous wealth in oil, uranium, and iron. The part time prospector will likely engage in prospecting during vacation time, and week end tours of a few days. The latter tours will be limited to dis­ tances within easy reach. The prospector residing in the more heavily populated parts of the Country will likely not find good nearby possibilities. Those who re­ side in the Western states may find good prospecting areas within a short distance. Certain metallic minerals, and some gem minerals are most likely to be found associated with certain types of rocks, and the prospector would do well to be en­ abled to recognize the more common rock types when seen in the field. For example, the pegmatite formations have produced a great host of valuable economic min­ erals. Pegmatites are nothing more than granitic rocks which have cooled very slowly at depth, and present very coarse single mineral crystals. In fact these single pegmatite crystals may be of enormous size and weighing many tons. Ordinary granite is compara­ tively composed of small crystals. A con­ trasting rock is obsidian, the volcanic glass that was cooled quickly on the sur­ face, and here the rock appears homoge­ neous, with no individual crystals visible. Yet both of these types of rock are of the same essential chemical composition. The same molten liquid that at great depth solidifies as granite or a pegmatite gran­ ite, would if it cooled more rapidly at or near the surface, form common obsidian, perlite, pumice or one of the several types of roek classed as rhyolite. It may be well to remember that the rhyolite type of rock is the home of valuable vein agate and agate filled thunder eggs, common to many Western states. We have spoken of chance as a factor in valuable discoveries. Ore bodies and gem deposits have often been exposed in the excavations made for buildings, roads, trails and railways. These have often proved to be bonanzas for gem and min­ eral prospectors.

In this little book we will not go into instructions pertaining to grub and camp­ ing equipment. This information has been previously presented hundreds of times. Nor do we dwel1 at length upon the mat­ ter of remedial treatment for snake bites. In all the voluminous literature on, and references to, mining and prospecting we have yet to read of an authentic case of a miner or prospector meeting his end through an encounter with a poisonous insect or snake, in the United States, Can-· ada or Alaska. History does reveal the fact that many prospectors who encoun­ tered fabulous bonanzas hastened their end celebrating their good fortune. In these matters we will assume that the reader is endowed with common sense and good judgment. Regarding the filing of mining claims, the U. S. General Land Office has issued an excellent booklet, which gives perti­ nent and salient information on the sta­ tus of various lands where claims mayor may not be filed. Send for Infonnation Circular 1278, U. S. Land Office, Wash­ ington, D. C. It has been previously stated that the prospector will find it a great advantage to acquire at least an elementary knowl­ edge of mineralogy, and at least a basic knowledge of geology. Without these the prospector might make valuable discov­ eries, but he is working under a distinct handicap. All the large oil and mineral exploration corporations employ trained geologists and mineralogists. There must be a reason. In many cases the field pros­ pector will make the original discovery, and after that development work will de­ pend upon scientific prospecting, includ­ ing the use of valuable geophysical equip­ ment and in most cases a considerable amount of costly diamond drilling to fol­ low and prove or disprove the ore body. If the reader is interested in acquiring an elementary working knowledge of mineralogy and geology, he is referred to that recent and excellent book by Pough, Field Guide To Rocks And Minerals, appearing in the book list on page 2. OCCURRENCE OF ORES The prospector should have a basic. knowledge of what types of rock are most likely to carry a given ore of metal. It has been said that "gold is where you find it." This is true in the case of gold,

8

POPULAR PROSPECTING

Part time Chicago prospectors. Members of the Chicago Rocks and Minerals Society re­ turning from a field trip to the Thornton Quarry, near Chicago. This club is one of some 500 similar clubs scattered throughout the United States. Most of them sponsor guided field trips to engage in prospecting, gem hunting, mineral collecting, and geological studies in the field. It is estimated that some 40,000 persons are members of these societies and clubs. News of their activities in various parts of the country appears regularly in the journals in this hobby field. (Photo courtesy of CHICAGO TRIBUNE.)

but not so in the case of many other metallic and non-metallic minerals. For example tin is frequently found associated with coarsely crystalline granite rocks, and is a common minor constituent of pegmatites. The great tin placers of Ma­ lay, Nigeria, and Bolivia, that produce the bulk of the world supply, are all asso­ ciated with disintegrated granitic rocks. Tungsten and molybdenum are nearly always found in or associated with coarse­ ly crystalline volcanic rocks. These may or may not be of a granite type. As a contrast, chromium, platinum, and nickel are usually found in or associated with fine grained volcanic rocks, like serpen­ tines and peridotite rocks, often greenish in color. This does not necessarily follow that wherever these rocks appear the minerals will also be found. Quite to the contrary. But their presence is an indica­ tion that valuable metals might be pres­ ent. It is weI! to understand that the valu­ able ores are usually not deposited at the time the molten rock came forth. The ex­ ception to this is in the case of the peg­ ,matite formations, often called pegmatite "dikes." In this case the individual min­ erals and metals had an opportunity to separate or "segregate," owing to the very slow cooling of the mass at some

depth. This is technically known as mag­ matic segregation, or separation of each mineral by itself. There are many im­ portant mineral deposits in this class. However, in most deposits we find the rock, either volcanic, sedimentary, or metamorphic (volcanic or sedimentary that has been altered) previously in place. The valuable metallic ores are then brought in by various means of trans­ portation, including percolating waters, (hot or cold) and gasses from the cooling lavas. The percolating waters (including steam), are by far the most important, and usually they are heavily charged with various chemicals, especially when they originate from depth. A huge mass of any type of lava rock, cooling at depth, will for many centuries give off heated, and chemically charged waters. These are what is known as "juvenile" or magmatic waters, and represent water which was originally locked into the rock in chem­ ical combination. It is these magmatic waters that ac­ count for the hot springs and geysers in Yellowstone Park. Gradually, over a riod of many years, the lava magma off less water, and the hot springs and geysers will eventually cease to flow, as has long been noted in Yellowstone. These magmatic waters are highly im~

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WHERE TO PROSPECT portant in the formation of valuable ore bodies. As these percolating waters pass through various rock formations on their way towa'"d the surface, they will dissolve various minerals and carry them in solu­ tion for at least a short distance. Even­ tually these mineral laden waters will reach an open space in the rock, and here they will deposit their valuable burden. These spaces. May be an open space formed by an earth movement (earth­ quake), or a large open "vug", or some other type of open space, or an open space may be created dissolving out other rock, like limestone. In open fissures, we find the great "vein" deposits. Or the percolating waters may drop their min­ eral load into porous formation like a sandstone, to form "disseminated" de­ posits. By no means does this complete the list of possible types of mineral deposits. Volumes have been devoted to their tech­ nical descriptions. The purpose here is merely to indicate the manner in which some well known mineral deposits have formed. It may be of interest to note that even metallic gold can be carded in solu­ tion by these superheated, chemically charged waters. The spectacular speci­ mens of native gold in quartz are good examples of this mode of ore deposition. The great gold nuggets of history, some of them weighing 100 pounds or more, were formed in this manner, when con­ ditions were right. Gold is one of the least soluble of all metals, yet under conditions of high tem­ peratures, and no doubt high pressures, plus the presence of various chemicals, water is enabled to carry gold in solu­ tion. This being true, it will be seen that far less resistant metals like uranium, copper, lead, zinc, antimony, silver, man­ ganese, and many others, may be readily gathered by percolating waters in their passage through any rock formation. The great lead-zinc deposits of the Tri-State district surrounding Galena, Kansas, are a· good example. Here the percolating waters likely mainly ground '.vaters, were acid in their composition, and as they penetrated the limestone rock, they dis­ solved and carried away the limestone (calcite), and dropped their burdens of lead, and zinc, along with small amounts of copper and iron, and minor amounts of lesser metals. These great deposits have been an important source of lead and zinc for many decades, and still con­ tinue to produce. Most of them are ncar the surface.

9

Huge opalized logs are sometimes found in the Western states. This specimen weighs 2,450 pounds and was found in the opalized forest of Central Washington, by Charles Simpson of Quincy, Washington. This speci­ men is from the Middle Miocene forests of some 15 million years ago. Specimens of pet­ rified wood, when of good color and quality, are valuable, and find a ready market.

It will be seen that many conditions must be met with in order to produce a rich and extensive mineral deposit. either metallic or non-metallic. At a compara­ tively few places in the world are occurrences quite exceptional in their nature. These resulted in the fabulous de­ posits of copper at Butte and Bisbee; the billion dollar silver lode of the Comstock; the enormous deposition of uranium at Great Bear Lake in Canada, and the Bel­ gian Congo, the mountains of iron ore in Labrador; the low grade copper at Bingham; unique Broken Hill, Australia; the wealth of gems in Ceylon; the gold of the Rand; the enormous phosphates (and uranium) of Idaho; and the Home­ stake with its unbroken dividend record of some 75 years. These are a few of the great mineral deposits of the world that have made and broken many men. The prospector interested in reading will find the many books dealing with the history and development of these great mining districts more interesting than any work on fiction, they are strang­ er than any fiction. It is not expected that the hobby-prospector will find bonanzas of this kind. Yet it is possible and has

10

POPULAR PROSPECTING

been done. In September, 1954, A. P. press reports throughout the Country carried the story of a lad by the name of Pick. Pick, according to the press reports had some hard luck in his home town in Minnesota. He took what funds he had in hand, and journeyed to Colorado, and according to press reports, bought a Gei­ ger counter, and the Handbook of Ura­ nium Minerals (by H. C. Dake, price $2.00). The news stories relate that this lad went out into the field, worked hard, covered a lot of ground, lost considerable weight, made some fabulous uranium dis­ coveries, and sold out to a large corpora· tion for $9,000,000 cash. The possibilities of the amateur prospector appear to be unlimited.

PLACER DEPOSITS In the earlier days of gold mining, the placers were the main producers. The gold from the original veins or lodes had gradually disintegrated through the ages. Gold being heavy and quite resistant to weathering, the heavy metal was con­ centrated at various places in sand and gravel, known as placer ground. First came the prospector working with a hand pan, or other hand operated equipment like rockers, sluice boxes, and long toms. The white man took the cream and went on to better grounds (presumably). Then came the Chinaman to clean up after the white man. Then came a long period of idleness, when along came the huge dredges, that again worked over the same ground to win ad­ ditional riches, and to work the ground too lean for any hand operations. Under ideal conditions, a dredge could often work ground at a profit, carrying as little as eight cents a cubic yard in gold. Today, placering for gold, as a possible one-man operation, is practically through from an economic standpoint. It is true that at times one may find an isolated pocket, or some ground here and there that will still yield a profit, but these are few and remote. Few of them were over­ looked by the Chinaman of an earlier day. Placer deposits, formed by the mechan­ ical concentration of valuable minerals, are still important to the prospe'ctor for values other than gold. By mechanical means, heavier minerals may be deposited in concentrates that are of great com­ mercial value. Usually the minerals that may be expected in commercial concen­ trations will include only those having

resistance to wear, weathering, tough­ ness, and they must be heavy (high specific gravity). These minerals include platinum, gold, cassiterite (tin), chromite, magnetite, ilmenite, rutile, monazite, zir­ con, native copper, and a number of others. Gem stones are often found in placers, like the sapphire of Montana, first noted and mined as a by-product from the gold dredges some decades past. The great alluvial gem placers of Cey­ lon have been known for centuries. To­ paz occurs with the tin deposits of Ni­ geria, and these large and superb gem crystals are well known. The gem placers of North Carolina were important pro­ ducers for many years, but have now been largely mined out, at least in the more profitable ground. Agate is often won from what may be regarded as plac­ er formations, notably the gravels of the Yellowstone river in Montana, and the Oregon beach deposits. In short, in any region where a hard and resistant mineral or gem has been found in place, it was often first found in placers. This is true in Montana where sapphire was first discovered in the gold placers, and later traced to its origin. At the present time considerable at­ tention is being devoted to placers yield­ ing ilmenite, monazite and zircon. New uses have been found for the metal zir­ conium, especially in the field of high fusing alloys. used in the jet engine. The U. S. Bureau of Mines has conducted a considerable amount of research work in the production and refinement of this metal, long regarded only as a laboratory curiosity. Many of the world's placers carry vary­ ing amounts of monazite, and this min­ eral is important for its content of rarer elements cerium. Some monazite is radio­ active, carrying as much as 18% thorium and will respond actively to the Geige; counter. Monazite varies considerably in composition, and in addition to thorium it may carry valuable rare-earth element~ like didymium, cerium. lanthanum, and others of this series. Monazite is commonly found in granite (gneiss) type of rocks throughout the world. Deposits in the United States in­ clude those of Virginia, Oregon, North Carolina, N ew York and Connecticut. Huge deposits are known in India and Malay. Ilmenite is a titanium mineral, long used as a white pigment in house paint. More recently new uses have been found

WHERE TO PROSPECT

II

Jade hunter in the Lander. Wyoming. jade fields finds two large and valuable masses of green Jade. Herds of antelope also roam this region. ranging far to the south in the great Red Desert. along with the uranium hunters.

for this very high fusing metal. Details of its use in the jet engine remains classi­ fied. but highly important. Placer grounds are comparatively easy to prospect and assay in a qualitative manner. A shovel and a gold pan will usually suffice to determine if possible values are present. Sample ground may be washed and concentrated in the gold pan. The heavy concentrates are collected and subjected to close scrutiny. The heavy black sand magnetite may be readily re­ moved with a strong hand magnet. The remaining concentrated material should be closelv examined with a hand fier. and' subjected to chemical and ger counter tests. If values appear, including those enumerated here, the concentrates mav then be submitted to a competent co~mercial assay. Placer ground may be found almost anywhere in or adjacent to a live stream of water. Ground far removed from water may have been originally worked over by running water. ocean or lake waves, or bv the wind. In either case there may be c~mmercial ground possible of standard placer treatment. In parts of Nevada and elsewhere in the desert regions of the \Vestern states, there are considerable areas comparative­

ly rich in alluvial gold, but no available water to work then. There are large areas of t!;lis nature surrounding Sulphur and Jungo in Nevada. During the De­ pression Days when there was wide in­ terest in gold placering, considerable at­ tention was given to the possibilities of working these great areas. The cost of bringing in water from a distance was prohibitive, so attention was turned to the recovery of the gold from the sands by the use of wind and an air blast. This method has proven quite successful in the highly arid regions of interior Aus­ tralia. Many of these devices were tried in Nevada, and elsewhere in the Ameri­ can desert regions, but none of them proved feasible or profitable. The present writer saw a number of these contriv­ ances in action. In some cases they yielded tailings that were richer than the concentr
12

POPULAR PROSPECTING

in this Nevada gold region. Among them were devices charged with a flask or more of mercury. The theory was to shovel in the gold bearing sands, and stir the mass with the quicksilver, with the idea that the finely divided gold would amalgamate. One device the present writ­ er saw in action was apparently working beautifully, until the sand started to pack in the drum. The iron paddles tore the machine apart, spewing forth the flask of mercury, said sand, and all. All of these inventors arrived charged with enthu­ siasm and high hopes, all of them re­ turned home, sadder but wiser men. Some day this problem may be resolved. Values in gold or any other metal may be found almost anywhere and in almost any placer formation, but in order to qualify for commercial value they must be of a reasonable extent and quantity. Small and isolated pieces of ground, how­ ever rich they may be, usually do not warrant any great development expendi­ ture. Grounds of this kind are the "one­ man" placer operations, operated by pick, shovel, wheelbarrow, and a suitably de­ signed sluice box for the material at hand. Many have profited well from small operations of this kind. The nature of the ground, said size par­ ticles, material being recovered, and a number of other factors will determine the nature of the best suited equipment. These are dealt with in mining volumes devoted to placering. An excellent book t1nder title Gold in Placer, price $2.50, is available from Jack Douglas, "The Old Prospector," Box 729, Lodi, Cali­ fornia. An interesting type of sluice box is used in Nigeria, Africa, in working the great tin (cassiterite) placers. The ground is first cleared of trees and brush, and then attacked with high pressure giants. The ground cut down by the water is washed into large sluice boxes ZOO or more feet in length, with low wooden ob­ structions at frequent intervals. A great deal of ground is poured into the sluice, and native workers constantly rake the debris in the sluices to keep it moving along. The cassiterite, being considerably heavier than the waste material accumu­ lates on the up stream side of the low obstructions. The cassiterite is scooped out at frequent intervals, and during the dean-up the water and ground is turned into a duplicate adjacent sluice. Fine to­ paz crystals are also recovered in the sluices, topaz being about twice as heavy

as ordinary rock, it will lodge in the rif­ fles, and is recovered as a by-product. In the Nigerian tin placers we have a good example of where a once worth­ less mineral was eventually turned into greater profit than the original product. A considerable amount of tantalite and col­ umbite is found in most of the cassit­ erite placers. At one time the tin con­ centrates were penalized if they carried over a small percentage of tantalite-col­ umbite minerals. Hence before shipping the tin concentrates to the British smelt­ ers, it was necessary to remove them by electro-magnetic treatment. The waste concentrates were thrown to one side. Then the tin buyers noted that the tin concentrates brought in by the natives carried more and more of the discarded waste. Pits were dug and the waste was then buried deeply, to pre­ vent the natives salting their concen­ trates. Some years later new and impor­ tant uses were found for tantalum and columbium. The original waste by-prod­ uct became far more valuable than tin. The old waste pits that had accumulated for decades were sought out and worked as valuable bonanzas. Here history re­ peats itself many times in the mining in­ dustry. The classic example being urani­ um, which we once threw over the dumps and tailing waste piles. The lesson we learn is that no matter how lean a pres­ ent day deposit may be, or how little, if any, value a mineral may have today, tomorrow it may graduate into the com­ mercial money -group. Perlite is another good example. All Western prospectors have walked past these mountains of volcanic glass and given them 110 thought whatsoever. Placer grounds may be found high up on the side of a mountain, or on a high bench far removed from any body of water. These are ancient water deposits, left by a flowing stream, or perchance the beach of a prehistoric lake or ocean. Formations of this kind are not always easy of recognition. They may be covered with a heavy forest growth, or debris from above may have wholly or partly covered the original ground. Some of these deposits have proven valuable once they were recognized and prospected. Some small but fabulously rich gold plac­ er grounds have been located high on a mountain or hillside. For obvious physi­ cal reasons deposits of this type are invariably of small and limited extent. Some of these small placers have been enormou~ly rich. In mining terms, values

WHERE TO PROSPECT

13

Part time prospectors. The Zeitner family of the , South Dakota, collecting chalcedony gebdes in the Bad Lands of South Dakota. The large geodes are erroded from the sedimentary formation, seen exposed here. Various good quality gem minerals have a wide and ready market.

in placer grounds are usually stated at so much per cubic yard of ground. The early day gold placers of Californ'a and Alaska were often rated in values of dollars per pan. Individual small pockets would vield thousands of dollars. In the Klondike, values ran as high as $5'0.0'0 or more per cubic yard in spots, when gold was priced at $20.65 an ounce. In many parts of the world gold placer ground has been known to run as high as $200.'0'0 per yard, at old gold prices. Henc" it will be seen that these old timers, using only hand labor, had no difficulty washing out fortunes. A dollar a today would be a great bonanza for a or hydraulic operation. GEM STONE PLACERS Diamond is perhaps the most impor­ tant gem won from placers. Prior to 1871, when the diamond "pipes" were first found in South Africa, the entire world supply came from the placers of India and Brazil. Diamond bearing placer grounds are stil1 worked in many parts of the world, but they are gradual1y being worked out. In India it was at one time thought that diamonds actually "grew" in the placer grounds, this statement appears in all the older books on gems, and was even copied as a fact by some quite mod­ ern textbook writers. The reason for this

eJ.r1y day supposition was that placer grounds in India would be worked over by native hand labor, and a certain re­ covery made. Then the ground was al­ lowed to rest for a few decades, presum­ ably to give time for diamond growth. Then the ground was again worked over and another crop of diamonds recovered. Some grounds were worked over many times, and in each case a recovery was made, often due to improved methods or more diligent and careful labor. Isolated diamonds have been found in placers in almost every part of the world including the United States. Almost every state records some of these finds. In the Mid-west region, the diamonds found found were no doubt originally brought down from the far North by the Glaciers of the Ice which covered a sub­ stantial part the Mid-west region. A goodly number are reported to have been found in the gold placers of the Western states in the earlier days. Perhaps many went over the sluices or. if noted, were not recognized at such. A diamond in the rough, appearing in a sluice box or gold pan, would not attract attention of the untrained eye. We have authentic record:t of only a very few being ac­ tually recovered. Nearly all the reported recent finds have proven to be either water worn topaz or quartz crystal. If you think you have found a diamond.

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just go to the nearest garage or machine shop, and touch the suspect to a spin­ ning grinding wheel. If its real, a cloud of dust will come from the grinding wheel. Any other known gem or diamond­ like material will instantly show a flat spot which the wheel has removed. Your diamond will wear down the whole wheel, and still remain intact. There is no need to send the stone to Tiffanys or any other place. Make the test yourself and be con­ vinced. "Soft" diamond is unknown to science or anyone else. Attention may be called to the fact that a sapphire would grind away rather slowly on the grinding wheel. But the wheel would readily leave its flat mark on the stone. Sapphire' and grinding wheels (silicon carbide, carborundum) are of about equal hardness. Many fine sapphires of commercial value have been found in the gold placers and stream beds of Montana. In fact for many years, gold dredges operating in some parts of the state, recovered sap­ phires as a valuable hy-product. Com­ mercial operations for sapphire are also conducted in Montana, with gold as a by-product. For many years these op­ erations were conducted by British in­ terests, and all the gem quality stones were shipped to the gem cutting centers of London. For this reason we have no accurate records of the value of sapphire found in the state. However, the valuable and well colored cornflower blue sap­ phire from Montana is widely known and highly rated in the gem trades. Like in all gem deposits over the whole world, only a small part of the sapphires found in Montana are of valuable gem grades. The great bulk of them are either off color, badly flawed, filled with inclusions or other imperfections to render them worthless for gem cutting. At one time these were widely utilized in the watch making industry as jewel bearings, until the synthetic sapphire industry was de­ veloped to largely replace the natural stone. A few decades past, gem and min­ eraI supply houses had boxes filled with Montana of non-gem grade, but show­ ing the typical six-sided crystal charac­ teristic of sapphire. The larger ones av­ eraged about y,; inch in size, and it was your pick at 10 cents each. There are stilt many areas in Montana today where you may pan for sa~hires. The best known of these regions include, the gravels of Clark river at Missoula; Y ogo Gulch in the northeastern part of the state; Pole Creek, Elk Creek, and

A typical Montana sapphire and gold placer operation. A giant, as shown, is used to wash down the debris into sluice boxes where the values may be recovered.

Bear Trap Creek, west of Bozeman. Per­ haps the best sapphires have been found along the Missouri River, north and east of Helena, on American Bar, Dana Bar, Eldorado Bar, French Bar, and several other localities on a long stretch of the river. We have seen many colorful parcels of sapphire panned from various streams by Montana gem hunters. Few of the stones found have been of high gem value, but they come in many colors including blues, greens, browns, yellows, orange and near­ ly colorless. Those who are interested in extensive prospecting for Montana sap­ phire wilt be interested in U. S. Geologi­ cal survey Bulletin 983, available from the Government Printing Office. Wash­ ington, D. C. Most gem prospectors visiting Mon­ tana are in search of agate, found mainly along the Yellowstone River, and in the adj acen t hills north of the river. Over a period of more than 75 years this area has produced millions of dollars worth of valuable gem grade agate, perhaps more valuable than all the sapphire ever found in the state. For many years this region was almost the sole commercial producer of gem moss agate widely used in the gem trades. Despite the fact that thousands of tons of this agate has been gathered during

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WHERE TO PROSPECT

15

A typical Southwestern desert prospect. Thousands of these "showings" are scattered throughout the Country. Some will develop into valuable properties, others will be abandoned. The prospect shown here may develop Into a valuable tungsten producer. Prospect of this type are usually explored by open cuts and pits, or by shafts, as shown here. Deeper and more extensive exploration may be conducted by more costly diamond drilling, if indica. tions warrant the expenditure.

the past 75 years, prospectors still make valuable finds in this region. Where in the past, a days hunt over the hills and along the river gravel bars would be }'eckoned in wagon loads, today a few hundred pounds is a good days work. Values depend on quality found. Like all other gem regions, many of the water worn agate pebbles and boulders are de­ void of attractive moss-like inclusions, and are thus worthless duds. Almost any type of mineral may be found in placer ground. For this reason alluvial deposits are a good indication of what might exist in the region drained by a stream. Tracing the source of min­ erals found in placers have often led to the lode - the original source. Soft and less resistant mineralS are not likely to long survive water transportation or to be carried far. With a little practice, some skill will be acquired in handling a gold pan. At the outset do not load the pan too heavily. The larger fragments may be tossed out by hand. The pan may also be used to test various types of rock, suspected of carying values. The rock is· first broken and powdered in an iron miners mortar. The material is then panned in the usual manner. This method of testing is ap­

plicable only to instances where the min­ eral element is considerably heavier in specific gravity than the mother matrix rock, like gold or heavy metallic sul­ phides carried in rock.

LODE DEPOSITS As a rule mountainous and volcanic regions are more favorable for ore de­ posits, especially the metallic minerals. In these regions we find faults and frac­ tures in the rocks which are favorable for the deposition of various minerals. Moreover, in a hilly or mountainous re­ gion conditions are generally more favor­ able for the exposure of outcroppings, indications of values below the surface. These may be lacking in a flat or ievel desert region. Hence in most prospecting work the prospector will first look for possible surface indications, outcrops as they are generally known. These are places where the vein or ore body below may be ex­ posed on the surface through weathering or other agencies. In regions of exten­ sive glaciation, like Central Canada, great ore bodies have been discovered where prominent outcroppings are lacking. Many of these ore bodies were located by vari­ ous methods of geophysical prospecting, and similar technical means. Some of

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POPULAR PROSPECTING

them were located by keen eyed and ob­ serving practical prospectors. Surface indications also include frag­ ments of ore, mineral or vein matter, broken loose from the ore body and found resting on the surface as "float." These float pieces can usually be traced to their source when found on a slope or in a wash. On a hillside, an outcrop may be covered with surface debris and not readily located, or it may be weath­ ered to such an extent to lack prominence. In this case the float may be traced up a slope or up a wash, until no more appears, when it is assumed that the ap­ proximate outcrop has been reached and digging is indicated. The steeper the slope or wash, the further the float may mi­ grate. In arid regions and on nearly level ground, float is not likely to travel far from its point of origin. Outcrops will vary in size and appear­ ance. Some may be great bodies of resist­ ant silica rocks, standing boldly above the surface. Others may be small and ob­ scure, lacking in prominence, but may be rich. The zinc-lead deposits surrounding Galena, Kansas, show no surface indi­ cations, but are extensive, rich, and rest near the surface. On the other hand the great lead-silver deposits of Broken Hill, Australia, comprised an outcrop that was a land mark to be seen from miles around. These, however, are two wholly different types of ore depositions. The former are of ground water origin, while the latter are associated with volcanic activity. Many notable copper mines have a large outcrop of iron oxide or gossan, and were originally worked as gold and silver properties. This was true in the case of Butte, the "richest hill on earth." Not much gold was found in the thin gossan capping, and at the outset little hope was held for Butte as a mining camp, by those who first worked the ground. There are a few general rules that may be kept in mind. A silicious rock in lime­ stone will form a conspicuous outcrop since the silica is much more resistant to weathering. Pyrite and similar heavy metallic sulphides weather readily,hence where these are present in large amounts, the outcrop may actually be in the form of a depression covered by gossan. Sili­ cious veins in volcanic rocks usually stand out on the surface in an irregular manner due to lack of uniform weather­ ing. In all cases the most resistant ma­ terial (like quartz) in an outcrop will sur­ vive weathering the longest, and often

monopolize the outcrop, even long after most of the values are weathered away. This may be the case on rich silver de­ posits. For this reason an outcrop mayor may not carry values representative of the rock below. Resistant minerals like gold, platinum, cassiterite, scheelite, and a num­ ber of others are likely to remain in the outcr9P along with the resistant quartz or similar matrix rock, but a great host of minerals will be subject to weathering, including the copper and silver minerals. For these reasons many mines are found ,yhich are fabulously rich near the sur­ face, that is in what is known as the zone of oxidation, that portion of the ground above the local ground water level. The zone of oxidation, will vary, depending upon the terrain and climate. In level, non­ arid regions it may be several hundred feet below the surface. The minerals found in the outcrop, and in the zone of oxida­ tion near the surface may be wholly dif­ ferent from the values and ores found at depth. There may also be considerable enrichment in the zones of oxidation, de­ rived from the values above. As the sur­ face ores weather, leaching and percolat­ ing waters carry these values downward, enriching the lower bodies. This continues down to the groundwater level where oxi­ dation ceases, and the sulphide ores are encountered. The latter ores are usually of. lesser value. Many of the early days silver-gold mines were of this type. Enormous wealth was encountered in the zone of oxida­ tion, where for eons of time values were siowly concentrated as they were re­ moved from above. This was true at all the mines in the Couer 'd Alene; at Butte; at Silver City, Idaho; in the Comstock; at Bisbee; and at practically every other similar deposit. All went well while the workings were in the zone of oxidation. Suddenly the sulphide zone was reached, where the values were often greatly de­ preciated, compared to what was first mined. Some of the great workings were enabled to carryon by improved milling methods, others like those of Silver City, Idaho, soon ceased operations. When prospecting, every physical sur­ face is worth noting. Odd or unusual col­ ors appearing on the surface should be investigated, for many ores when weath­ ering break down into minerals having bright or characteristic colors,· like the green and blue of copper, malachite and azurite. Sandstones and clays may be also stained by various minerals. Any unusual

WHERE TO PROSPECT

17

Part time prospector H. F. Mack of Project City, California, makes a lucky and valuable find - a huge water worn bnulder of Jade, weighing 1,350 pounds. This mass was found in Shasta County, California. This mass rates along with the other large masses found in Wyoming anti elsewhere. California and Wyoming are the only two states where jade has been found insau. There are several known producing jade fields in California, described in some detail in the book CALIFORNIA GEM TRAILS. The finest quality, apple-green, American jade ranges in value at $50.00 per pound in the rough:

color appearing may be an indication of mineralization below and adjacently. While color in an outcrop is no certain criterion of values present, some color generalizations may be made. It can be stated that some mineral colors are always bright and vivid, like the green and blue of copper and nickel. Chromite in an out­ crop may also present a vivid green color, but more rarely than copper or nickel. Co­ balt sulphides in an outcrop may also weather to a beautiful pink colored cobalt mineral. Pitchblende, a primary uranium mineral is notorious for its production of vividly colored secondary u ran i u m minerals, formed by weathering and alteration in the outcroppings and near the surface ores. These include some 75 or more dif­ ferent secondary uranium minerals, most of them rare ones seldom seen outside of collections, but others are much more

common and include a number of com­ mercial uranium minerals. Reference to those will be made elsewhere, but suffice to state here these bright colors include canary yellows, blues, greens, and green­ ish-yellow, orange and several mixed shades. While carnotite is usually not re­ garded as a primary uranium mineral, it presents, when pure a bright yellow color not to be forgotten when once seen. The more impure carnotite ores will tend to­ ward dull or muddy yellow or even brownish colors. Iron stains are common ones, seen al­ most anywhere and every where, however, they may appear in many colors and many shades of colors, they are never vivid as stains in outcrops on and in rocks. The more common iron stains are yellowish and reddish, but always on the dull side. Iron stains and iron minerals may also appear as black in color. Ferrous iron

PROSPECTING may account for green stains that to the untrained eye may be taken as a copper stain, but these green stains of iron are invariable a dul1 and muddy green, never bright and vivid like those of copper. More rarely iron may appear in the form of a blue stain, the iron phosphate vivi­ anite. Or the color may be a bluish-green, but again Iilot the vivid copper color. Iron mineral stains probably mislead more prospectors than any other mineral stains. Mineral stains appearing in outcrop~ pings can lend valuable information and the prospector will do well to take note of these. Even silver may cause a brightly colored stain in an outcrop. The silver chlorides and bromides, may present bright stains in green, yellow or blue, easily mistaken for some other mineral. It is difficult to specifically tell the reader where to prospect. We may cite a few anecdotes. Years ago a greenhorn ventured into an Australian mining camp, and innocently asked a party of opal gougers where to dig for opaL As a joke, they directed the novice to a barren knoll where no experienced miner had ventured to work For days the amateur sunk his shaft deeper and deeper, until the experts were about to reveal the hoax. Without warning he suddenly struck one of the richest finds in the whole field. Shafts were sunk all around him, he had struck a new bonanza. Some years ago, an old timer, ]. L. Stoddard, at Silver City, Idaho, related to us how he discovered the fabulous silver camp. Stoddard was what may be called a part time prospector. A t the time of his discovery he was not prOS­ pecting, but he and two other men were running a band of horses from Nevada to sell in Boise. No, they were not horse thieves. Stoddard was rather a handy man with the frying pan so he was delegated as camp cook, while the other two were busy wrangling horses and bringing in game. It was cold weather, so Stoddard built his camp fire against a rock wall, to provide a better heat. Next morning while scratching around in the embers, he noted some bright looking metal slugs, too hard to be lead as revealed by the knife test, and too hard to be iron. More-

Large and good quality quartz crystals as shown here held high value for use in many electronic instruments, including radio broad­ cast control. Few suitable crystals of this kind have been found in the United States. During the last war, great quantities were flown from Brazil mines at a high cost.

over, Stoddard knew that his frying pan was intact, yet the partners did not sus­ pect silver. A few of the slugs were taken by the partners to an assayer in Boise. The as­ sayer placed one of the small slugs into nitric acid, watched it dissolve, and then precipitated white silver chloride from the clear solution, by the addition of common salt. Yes, it most certainly was pure sil­ ver. Stoddard had accidentally set his fire against a rich outcropping vein of silver. This was in the early 1870"s. Dur­ ing the next several decades some $300,­ 000,000 in silver and gold was won from the mines of Silver city. The mines of Silver City are rated as the richest the world has ever known for their size. As mines go most of them were small and of limited depth, when the sulphide zones were encountered. This was before the income tax days, and several notable present day family fortunes were founded on the wealth of the mines of Silver City -a ghost town today, still more or less intact as when some 5,000 miners and 500 Chinamen trod its main street.

CHAPTER TWO

The Gem Minerals Twenty years ago there was little popu­ lar interest in gem cutting as a hobby, and we found few gem hunters in the field. Most of the gems used in the jewelry trades were mined and cut in foreign countries. Most of the domestic gem min­ ing was confined to gem pockets en­ countered in pegmatite formations, and non-metallic mineral quarries, where gems were not the primary interest, When a gem pocket was encountered in these mining and quarrying operations, it often proved a bonanza. Commercial gem d e p 0 si t s may be placed in two different groups, the placers and the lode deposits. For more than 75 years western stream gravels have supplied the gem markets with agate, and while these continue to produce, ,they have been largely depleted in most sec­ tions of the country. Now most of the value gem grades of agate are dug from veins, seams and pockets. Often a pocket of agate will yield heavily and if the material is of good gem grade, a single small pocket will produce as much as

$5,000. The home of agate is in the volcanic rocks. and as these rocks weather and disintegrate the much more resistant agate is released to find its ways into stream IJeds or in arid countries it will accumu­ late at the foot of slopes, or remain rest­ ing on the surface. Usually when a new agate field is discovered, a great quantity of material is found on the surface or mixed with the surface debris. This is the picture in an arid or semi-arid area. The lack of surface plant growth makes re­ covering the agate masses easy. \Vhere brge streams are adjacent to lode agate, the gem will then be found in the streams, as water worn material. This was the case of the celebrated moss agate of the Yellowstone River in Montana. Over a distance of more than 75 miles in the eastern part of the state, agate was recovered in considerable quan­ tity. by merely searching the gravel bars during summer low water periods. It is related that in the earlier days, a wagon load of agate could be gathered in a day, searching the gravel bars. Like all other placer deposits, these have become depleted, and now the masses of agate are found strewn along the slopes and in fields, miles back from the

river. The best hunting is in the hills north of the Yellowstone. Apparently the agate originally occurred in the lava rocks over a great area, but mainly in the rocks north of the river. For this reason they are found scattered over large areas in the present day. In many cases the gem placers have served, like in the case of gold, to trace the values to their source or origin. In a hilly country, where gem materials may bt: found in dry washes, canyons, ravines, and stream gravels and sands, by search­ ing upwards the source can often be found in the form of a lode. In a gem country, the debris, for example at the mouth of a canyon or ravine, may reveal the presence of small fragments of the material sought for. One may have to make a close search, but if even sman fragments appear, one may be reasonably sure that following the material upwards will rev e a I its source. Many valuable pockets of opal­ ized wood have been found in this maimer in the Horse Heaven hills and in the Saddle Mountains of central Washington. This method of prospecting for any type of mineral can not be stressed too often. It is a time worn method that has been in effective use for centuries. A method that nearly always leads to values. The debris referred to may even be sub­ jected to panning to learn more of its nature. If fluorescent minerals, like tung­ sten, scheelite, are suspected, the ultra­ violet lamps should be used, and if urani­ um minerals are being sought, the pan­ ned concentrates may be tested Vlrith the Geiger counter. In short, these water car­ ried alluvials can reveal a great deal of valuable information, and mean a lot labor saving. In some regions, many of these washes are noted dissecting steep slopes, hence a lot of ground may be ef­ fectively prospected at a small amount of effort. While most of the former rich alluvial agate ground in Montana, Oregon, Texas, California, Wyoming, and other western states has been largely depleted, present day lode workings are the rich producers. Some of these in situ deposits have been brought to light by construction work, like highway excavations, digging wells, dam construction and similar activities. Not so long ago a slide on a highway in central Oregon revealed an agate pocket

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20

POPFLAR PROSPECTING

comprised of high grade gem agate. The discoverers, in a matter of hours cleared out the open exposed pocket of vein agate, material that sold readily for from $5.00 to $6.00 per pound in the rough. One single mass from the pocket weighed 165 pounds and was sold to a commercial gem cutter for $1,000. This was the largest single piece found, but all the material was in fairly large pieces. At values of from $5.00 to $6.00 per pound, a pocket would not have to be large to yield sev­ eral thousand dollars in values. Agate was gathered on a commercial scale in Montana and Oregon for more than 75 years before attention was di­ rected to other agate deposits in the west. The great agate deposits of Texas, Ari­ zona, and New Mexico appear to have re­ mained unknown or at least untouched until the last two decades. Since then through active prospecting, the great Big Bend of Texas agate fields have become well known, and important producers. Commercial agate diggings in Arizona and New Mexico have also been revealed by prospectors, during the past 20 years. III Oregon, agate mining and agate cut­ ting has become an important part of the mines products of the state. Gem min­ ing and gem cutting, has become a million dollar annual industry in the state, with scores of well known producing prop­ erties. Nearly all these new deposits, re­ vealed during the past 20 years, were originally found by gem hunters. All the producing grounds are lode deposits. Some are operated by hand labor, but the better known ones are worked by power machinery. There are millions and millions of acres in the great Public Domain of the West­ ern states. Here the gem hunter may roam at will, dig, and gather material with no restrictions whatsoever. Upon this great Public Domain many new lo­ calities have been found, and still more await discovery. It seems needless to call attention to the fact that private property is generally surrounded by a fence - in the Western states it is usually a barb wire fence. The Public Domain is not fenced. Those who are brash enough to barge into fenced land, cut wire fences, tear down gates, will likely find them­ selves in more or less difficulties - if the land owner happens to be in the vicinity. Only in rare cases will permission be denied those who seek permission from the land owner. And where this is refused, or where signs are posted, there is always a good and sufficient reason for same.

A good quality agate "nodule." The rough mass has been sawed in the middle, and this shows the flat sawed surface. This type is called banded or fortification agate. A good market exists for specimens of this type and quality.

But even in these limited instances, it is often possible to gain entry by proper approach and technic. It is likely that as time goes on, more and more private property will be posted against entry or trespass. Many of these postings are pri­ marily aimed at the flesh hunter armed with a shotgun or high powered firearm, and not the gem hunter armed with pick and r.ammer. As a general rule when your business is made known to the prop­ erty owner, you will be made welcome in the true Western fashion, and no one would dream of taking advantage of or violating this courtesy. If you wish to spend a vacation in the field on an extended tour, it is suggested that you plan your tour in advance and with specific routes and localities on schedule. An aimless wandering over the region will likely yield very little, and not enhance the recreational value of the jour­ ney. In addition to the information pro­ vided here, there are other sources of helpful data. Various books will provide additional information pertinent to lo­ calities, and their general geology and mineralogy. Many of the state mining bureaus have bulletins of a helpful na­ ture and while these are not intended primarily for the gem hunter, they are usually of value in field work.

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THE GEM MINERALS

21

Gem hunters at work at the noted Ochoco carnelian agate thunder egg deposit in Central Oregon, operated by Herbert Wm. Lawson of Terrebonne, Oregon. One of the several open to the public commerc!al diggings in the Central Oregon region. Diggings of this kind have proven widely popular with visitors from distant places. The Ochoco deposit, situated high up In the cool of the Ochoco Mountains, is celebrated for its rare and large carnelian agate filled thunder eggs. Power operated equipment is used to clear away the waste overburden materials to render digging easier.

The various journals in this field also publish locality data at frequent intervals. The journals will also enable you to visit supply houses en route, as practically all supply firms, and individuals who sell, carry advertisements in one or more of the magazines devoted to your hobby. The silver pick will always enable you to return home with fine material, regard­ less of your luck in the field. It may be just as well not to attempt to visit too many localities in a limited time. T hurried or superficial visit to a locality will seldom be worthwhile. After all, the specimens generally have to be searched for, dug out, gleaned from some dump at an old mine, or perhaps won from the hard rock matrix in a quarry. A visitor may read of some 10caFty and after a visit will complain "there is noth­ ing there." This is usually not correct. The stranger has failed to find the best spots, or has failed to spend enough time in diligent search, or for many other rea­ sons. Many of the superb specimens we see from some noted locality were col­ lected by persons who had perhaps visited the region dozens of times. It is better to spend a full day at one locality than a few hours at several places. Remember, when you are sitting at the wheel of the car, bowling along at 50 per, the scenery may

be excellent, but the trunk is not being filled. Do not be too hasty to blame the writer of a locality, or feel that he has first cleaned out the locality. and then passed along the information in the form of an empty sack. This is seldom the case, Likely, the writer did obtain all the fine material claimed, but failed to state bow many hours or days were devoted to their acquisition. For the benefit of the inexperienced, we may add a few words regarding col­ lecting conditions in various parts of the country. In general, there are two types of localities, one where the material is found in its original place of birth, and the other where it has been weathered out. The pegmatites of southern California, South Dakota, North Carolina. and the New England states are excellent sources of a great many gems, and valuable min­ erals. The pegmatites of southern Cali­ fornia were for some years worked for the gems contained plus rare minerals found, including lithium. Rock, limestone and various other types of quarries are plentiful throughout the Atlantic states. Often "pockets" are en­ countered in quarrying, and these poc­ kets may contain mineral crystals often superb zeolites. As long as the quarry is in active operation specimens are likely

22

POPULAR PROSPECTING

to be forth coming, and these commercial operations remain under the eagle eye of local collectors. The locality of Clay Center, Ohio, is known to collectors far and wide for its remarkable fluorite and celestite. All Clay Center specimens come from an enormous limestone quarry,. a hole in the ground about the size and shape of Meteorite Crater of Arizona. One could spend days and days in the Clay Center quarry and yet not cover the entire terrain. Tools are needed here. The river gravels throughout the United States are good sources of specimens, usu­ ally hard-water worn material. Since the high waters each year work over the river gravels, we may expect a new crop each year. Here are localities which will never be depleted. The Rio Grande River, up and down stream for over 50 miles from Laredo, Texas, has yielded great quanti­ ties of good specimens, mainly water­ worn quartz family minerals. Obviously we would not expect to find soft or fragile minerals among the river gravels. Gold is the soft exception to the rule. Let us go down to Florida and observe the collectors at work at Ballast Point, Tampa Bay. Here the collector wears rubber boots, carries a small crow bar, and generally a pair of heavy leather gloves. Coral, which has been petrified with beautifully colored chalcedony and agate, may often be obtained in large masses or fantastic forms. The specimens are broken off from their attachments in shallow water and at low tide. Collecting has been carried on here for years, and yet the supply does not appear to have been greatly diminished. We can cross the country and nearly all' along the Pacific Ocean beaches fine agates and other quartz minerals may be found in the gravel bars along the beach, with best collecting at low tide. In Ore­ gon a good gravel bar may be suddenly covered by sand or exposed by a storm or change in tides or wind. A gravel bar may remain "sanded" for years and then suddenly be exposed, to the good fortune of the first combers. So if you visit along the Pacific Ocean beaches, do not be sur­ prised to see numerous persons walking slowly along the beach with heads bowed down. They are not in silent meditat:on­ merely gem seekers. It is true that there are great areas ill the Mid-West that hold little interest for the collector. Much of this region is level prairie country. However, there are some

good collecting grounds here. The "strip" (open cuts) coal mines near Wilmington, Illinois, produce some of the most beauti­ ful fossil flora to be found anywhere. Col­ lectors glean the waste dumps of the stripped surface material in search of the elongated concretions. When split open lengthwise these frequently reveal the imprint of some leaf or plant that thrived millions of years ago. At numerous places in the Mid-West there are huge gravel deposits carried down from the far North by the Pleisto­ cene glaciers. Here one may expect to find almost any mineral which can sur­ vive water wear, including even native copper carried down from northern Michi­ gan. Colorful quartz minerals and fossil wood is common to these gravels. Some of these gravel deposits are worked in a commercial manner, which serves to ease the labors of the collector. Throughout the western half of the United States there are large mining re­ gions which offer excellent possibilities. At many mines it is customary to throw the waste or lean material removed from the mine workings on huge dumps. Since this is waste materi,t1 there are generally no restrictions on coil e c tin g. Mining states like Colorado, Arizona, New Mexi­ co, California, Uta h, Nevada, Idaho, Washington, Oregon, and others, boast of thousands of these "dumps" ranging in size from the small dump of the pros­ pect pit, to those containing hundreds of thousands of cubic yards of material. Often these dumps contain material of interest and value as specimens. Some of these dumps represent material which may have been removed from the mine 50 to 75 years ago, still waiting for the collector. Several years ago the writer spent four successive summer vacations at the old mining camp of Silver City, Idaho, some 50 miles from Boise. Here large and small waste dumps dot the hill­ sides by the thousands. These old and sleeping mining camps offer not only excellent collecting possi­ bilities but they are often off the beaten path, high up in the mountains, and an excellent place to spend a few weeks away from the rush of the city and the busy highway traffic. Some fine material may be obtained from old mine dumps. In the early days of mining when fabulously rich ore was encountered, it was customary to care­ lessly cast away valuable ores. The op­ erators were waxing rich, and often the miners were careless. Some of these old

THE GEM MINERALS

23

While agate and many other gems are found in alluvial deposits, some are being won from veins. Showing mining valuable gem agate from a vein deposit in Arizona. Huge masses, weighing hundreds of pounds may be obtained in this manner. Photo by Charles Hill, Cave Creek, Arizona, agate mines.

mine dumps have long since been re­ worked and run through the maw of the crushers in the mills, but a very large number, not large enough, or not con­ veniently situated, still remain intact. Collecting on a mine dump often re­ quires no more equipment than the cleav­ ing hammer. It is easy and pleasant to sit at the foot of a dump and rake down and sort over the debris for specimens. In the dump of an old silver property, it is not at all uncommon to retrieve a fine rich silver specimen originally overlooked or cast aside through carelessness. Then the beautiful crystals of the gangue minerals, and the zone of oxidation minerals, are always present. Your entire vacation can be spent with pleasure and profit at one of these old mining camps. Depending on where you prospect you will require an assortment of tools and packing materials and containers. Work­ ing in hard rock, chisels and hammers are indicated. If you visit one of the sage­ covered desert localities of the west, you will want a heavy pick and shovel, as when surface material is lacking, digging may be indicated. If you expect to collect fine crystals and similar fragile material take along pack­ ing material and suitable containers. Mas­ sive or water-worn materials can be safely cast into a burlap sack and dumped in the car. In a\1 cases take along a supply

of labels, and on each container place the proper label. Your memory may prove faulty when you return home. You will, of course, always have your prospector's pick handy; this is your most universal single piece of equipment. The novice at gem hunting will likely not be enabled to readily recognize good material when it is seen in the rough in the field. This is a matter that requires a little experience, to enable ready "on' sight" recognition of suitable gem cutting material. The novice is just as likely as not to cast away valued pieces and return with almost worthless material. In some cases it is difficult for even the more ex­ perienced to recognize a good specimen, especial\y where the exterior is water worn and drab in color. Usually chipping off a small corner of a specimen will suffice to reveal its true quality, on the freshly broken surface. Or it may even be necessary to saw off a section to view the interior, as is the case with a\1 intact thunder eggs, nodules, and the like. In order to gain a good working knowl­ edge in the proper recognition and ap­ praisal of rough gem material, the novice will do well to view the specimens in ad­ vanced collections. Or typical material of specific value and quality may be pur­ chased from supply firms, in order to en­ able the novice to separate the sheep from the goats, as it were.

24

POPULAR PROSPECTING

A great many of the supply firms in various parts of the country are largely dependent upon the field worker to re­ plenish their supply of rough gems, min­ erals, fossils, and geological specimens. The hobbyist coIl e c tor will invariably obtain more or less duplicate material, and if this is of suitable commercial qual­ ity it may be readily disposed of in quau­ tity to supply firms. Many home gem cutters manage to make the hobby pay its way through dis­ posal of surplus material finished in their home shops. This income frequently suf­ fices to pay for wheels, saws, and other necessary supplies. Poor quality material i, in little demand, it is quite common, and often hardly worth the cost of lapi­ dary treatment. It costs no more to apply lapidary treatment to good quality ma­ terial than it does to inferior junk. In selling to a supply firm, retail prices are not to be expected, the dealer must meet the cost of handling, selling, advertising, and realize a profit in the transaction. Few other hobbies hold comparable pos­ sibilities and versatility. The readers who are interested in pros­ pecting for gems in the Pacific Northwest region are referred to the book Northwest Gem Trails, listed on page two.

THE JADE FIELDS For many years the Orient supplied all the jade used in the American gem trades. A few pieces of jade float had been found at various places in the United States, but little thought w~s given to the exist­ ance of possible domestic deposits. In 1935, two Lander, \Vyoming pros­ pectors brought in some heavy but drab appearing w ate r w 0 r n boulders. This marked the discovery of the great \Vyo­ ming jade fields centered around Lander. During the next ten years a heavy influx of gem hunters and prospectors worked the barren hills in the Lander region. Few of them failed to find valuable jade. While jade has been found in position in the Lander region, alI production to date has come from what may be termed placer deposits, since all the masses of jade found show more or less water wear. And in nearly all cases the jade (nephrite variety jade) has been found resting on the surface, in surface debris, and in dry washes. Naturally these were soon de­ pleted but jade is still being found in Wyo­ ming comes into the high grade class. Mu.ch of it is lacking in good green color, or It may be too opaque or dull, and suit­ able only for carving work, and not for gem cutting. However, many tons of fine

Tracks across the sage. The prospector in the Western states, seeking out little known trails to reach isolated regions, is often con­ fronted with auto tracks branching In vari­ ous directions, with no sign posts to mark the correct route. This is typical of the Red Desert region of Wyoming. False tracks may lead one to a summer sheep camp. The ex­ perienced prospector will generally know what trail to follow.

apple-green jade has been found in Wyo­ ming. In the earlier days of discovery, this fine jade was at times sold for as low as $5.00 per pound in the rough. Now the same grade brings from $50.00 to $75.00, and the supply is not plentiful. Some of these valuable masses weighed as much as 185 pounds, but most of them ranged fro m 10 to 45 p 0 u n d s each. Enormous masses were also found, some weighing as much as 4,000 pounds, rating among the largest masses of jade ever found any w her e. One of these large masses, weighing about 2,700 pounds may be seen in the Chicago Museum Natural History. Several years ago jade was also dis­ covered in California. While California, including several localities, has produced a quantity of jade, little of it is of a color and quality suitable for gem cutting. How­ ever, magnificent ornaments have been carved from this material. Wyoming and California are the only two states where jade has been found in position, or in commercial qua n tit i e s. Isolated float p!eces of jade have been picked up from time to time at various places in the Country, but nearly always these have been pieces showing traces of having once been worked, similar to the jade found in old Mexico. A jade boulder or mass found in the field, may easily passed by as just another common roc k. 0 r w hen jade occurs mixed with common rock, it will be dif­ ficult to separate same by outer appear­ ances. The experienced jade hunter will be enabled to readily distinguish jade from common rock, solely by hefting.

THE GEM MINERALS

25

• Alaska Gem hunters en route to the fabulous Jade Mountain in the Kobuk River region of Alaska. During the summer months, the jade fields can be reached by canoe travel. Little hunting or prospecting has been done in this notable Jade field, owing to its isolation. A detailed description of a visit to this region appears in the June 1953 issue of The MIn­ eralogist Magazine.

With a little practice this skill can be acquired, since jade is about twice as heavy, bulk for bulk, as common rock. Sampling a mass of jade for quality, by breaking off a small fragment. may' also be deceptive since jade often has a worth­ less outer crust, due to weathering of the mass. The inner portion or inner core may be high grade and valuable material. Due to its fibrous structure. a water worn mass of jade will be very difficult to break by ordinary hammering. The mass should be brought in and diamond sawed by an experienced rock cutter. While there have been no spectacular discoveries in the "Wyoming and Califor­ nia jade fields in recent years, these areas have continued to produce small quanti­ ties of good material. The reader who is interested in working the California jade fields is referred to the specialized book California Gem Trails, listed on page two. This book also describes many other Cali­ fornia gem fields other than jade. Opal Common colored opal, that is opal which. is colored but now showing flashes of color as seen in precious 'fire" opal, is found in many parts of the coun­

try. Common opal, when well colored. and not too opaque has value in the gem trades. Some of this opal may be drab colored, or colorless, and it mayor may not show a strong yellowish-green fluo­ resence, due to the presence of small amounts of uranium. The colorless type i, usually called hyalite. or hyaline opal, and often found as coatings on volcanic rocks. Uranium fluorescent opal has been found, in Georgia, Nevada, Arizona and elsewhere in the United States. Other than specimens, it usually has 110 com­ mercial significance. Fire opal, in commercial amounts has been found in only a very few parts of the Country, notably in Virgin Valley, Nevada, some 30 miles south of the little town of Denio, Nevada, at the Oregon boundary line. Here we find the only op­ erating precious fire opal mines in the Country. Opal prospecting has been car­ ried on here from time to time for many years. Much of the ground has long since been filed on and prospected. The cele­ brated Rainbow Ridge Mine, is the main present day survivor of many former properties.

26

POPULAR PROSPECTING

Sapphire. SOr.1e sap phi r e has been found at various places in the Country, including the gem placers of North Caro­ lina, but these have long since been worked out. Montana has produced by far the greatest amount of sapphire, and some of the old placer and lode pro­ ducers are still in operation. \¥hile not a great deal of sapphire prospecting is now being done in Montana, there are still good possibilities waiting. References to Montana sapphire have been made pre­ viously. Diamond: Diamond pipes or diamond groun'd have been found in only one place in the Country, near Murfreesboro, Ar­ kansas. This discovery was made in 1906, and for a time the ground was worked on a commercial scale with considerable se­ crecy. Apparently the venture was not a success, for after a time operations ceased. More recently the ground was opened to public digging for a small fee, with the stipulation, "k e epa n y diamonds found". Elsewhere in the United States, at various places, isolated and authentic diamonds have been found from time to time. These have been few and far be­ tween, we may state. Garnet. This common gem has been found in many parts of the country, often in placer grounds, or even in the ant hills of Arizona. In Idaho, at several localities, good gem grade garnets of large size have been found in stream gravels. Prob­ ably the finest star (asterated) garnets found in the Un i ted S tat e s occur in Idaho. These have been described in the book Northwest Gem Trails, by the pres­ ent writer. Good quality star garnet in the rough has a ready market. Garnet sands are also of value for abra­ sive purposes like the familiar garnet paper used in industry. Garnet is often associated with other sands, of detrital minerals having commercial value. Hence a deposit of this kind of the right quality and quantity could hold considerable com­ mercial value. Red garnet, present in large amounts, may color beach sands red, and are often termed "ruby" beaches, seen at a num­ ber of places throughout the world. The green sand. beaches of Honolulu are due to the presence of large amounts of the gem olivine (peridot). The ruby beaches of Nome are well known. These sands are usually too finely divided to have any value as an abrasive material, however plentiful they may be. Turquoise. This colorful blue and green

Sketch map of the Hart Mountain opal fields of Lake County, south central Ore. gon. This is one of the very few regions in the United States where "fire" opal has been found. A detailed description of this region appears in the February 1954 issue of The Mineralogist Magazine. An opal valued at $400.00 Is reported to have been found here.

gem was once mined in some quantity in Nevada, Arizona, and California, but pro­ duction is now at a low point. Not much high grade was produced at any of these early day workings. Rhodonite. This opaque gem of a pleas­ ing pink color, has been found at a num­ ber of localities in the western states in­ cluding California and Oregon. It was also found in the old mine working at Butte. This gem may be found in large masses and as water worn boulders along stream beds, in southwestern Oregon and Northern California. In good color qual­ ity it has value as a gem material. Included along with agate in the quartz family minerals, are a number of other gems that are worth investigating when encountered on a prospecting tour. These include the many types of jasper and jasp­ agate. The quartz gems are described in some detail, along with where found in The Agate Book, listed on page two. Gypsum is ordinarily not regarded as a gem material, but the alabaster variety is widely used as an ornamental stone, fashioned into various shapes. by carving and turning on a lathe. The alabaster of Wyoming and Montana at one time com­

THE GEM -----------------------------

MINERALS

27

---------------------------

Some magnificent Montana moss or scenic agates, from the noted Yellowstone River region in the eastern part of the state. Cut and polished agate gems of the grade and qual. ity, bring high prices, ranging from about $10.00 to over $50.00 for a single finished piece. These are by no means common, but the gem prospector never knows when a single large agate of this quality may be picked up in the fields, north of the Yellowstone River. Aver­ age Montana moss agate sells for around $1.00 a pound, but a single high grade rough agate may bring anywhere from $100.00 upwards. Phot shows cut agates in natural size. From the collection of Stanley Twedt, West Glendive, Montana.

prised a sizeable local industry in the production or ornaments and novelties for sale to tourists. Gypsum is also widely used in the arts and building industries, hence any deposit or indications of such are weI! worth investigating. In copper mines, various valuable gem minerals may be found in the upper work­ ings, or in open cuts and trenches dug while prospecting a copper deposit. These valuable gem materials include the fine green chrysocolla, blue azurite and green malachite. Much of this fine material was found when the great copper mines at Bisbee, Arizona were first opened. Later when the mines reached depth, these gem materials were no longer found in the workings. At one time, when plentiful, chrysocolla had only nominal value, now since good quality material is scarce its value in the rough may be $50.00 per pound and u p war d s. Gem prospectors have found high grade material on the old waste dumps in some of the great copper camps of the West. A large number of deposits of orna­ mental stones are being utilized in a com­ mercial manner. Many of these have long

been familiar to prospects, but it remained for some enterprising individual to promote the development and use of these materials. These developments in­ clude the utilization on common, but well colored rhyolite rocks, common to many parts of the West. The "Wonder Stone" of Nevada is a good example, and has been exploited for some years. More re­ cently in Oregon and elsewhere various types of colored lava rock deposits are being utilized with profit. In some cases the rock is used as mined for applications like ornamental rock .walls, and in rock gardens. In other instances the colorful rock is mined, and sawed into flat sections, and used like tile or brick, as ornamental fronts on homes or a business building, or per­ chance as an interior decoration in a night club. These natural occurring build­ ing materials as usually quite durable and resistant to weathering, and if they are of a pleasing color or pattern arrange­ ment, they can often be utilized as a building or ornamental material. There seems to be no limit to the utili­ zation of ornamental stones, and the

28

POPULAR PROSPECTING

present trend in architecture seems to be turning more and more to natural stones. We have seen many new ones brought into use dJriog the past decade. For years we have driven past a prominent rhyolite rimrock. Presently we see a large quarry operation going on. 'vVe hasten on in chagrin, when we realized we had years of opportunity to file claims on the ground, or purchase same for a nominal price. It would appear that almost any type of unusual rock, however common and prosaic it may appear in the field has possibilities for utilization in one way or another. For example some of this color­ ful rock tends to weather and break into large flat slabs. These large and angular slabs might make ideal flagstones for out­ . door use. Trucked into a city, material of this kind will often bring a fancy price per ton. I t would appear that the pros­ pector in the field would do well to give these seemingly worthless materials some thought. 0 f ten the y are situated on ground that is worthless for grazing or farming, hence it is likely to be Public Do­ main ground open to mining entry. Any deposit of this nature, on open ground, can be protected by filing a mining claim at only a nominal cost. Gem Obsidian. While ordinarily ob­ sidian may be best classed as an orna­ mental stone, it does find use as a gem, when found in suitable quality. The vari­ ous "iridescent" types found in California and Oregon, have been widely utilized as a gem material. Obsidian is often avail­ able in large flawless masses, hence this material is often cut into large ornaments like, book-ends, spheres, paper weights, and desk ornaments. Modoc County in California has produced great quantities of gem grade obsidian. The Modoc County locality lies about five miles east of Davis Creek, California, in the Warner Range of mountains and covers an area of about eighty acres. Ap­ parently the iridescent obsidian is re­ stricted to this area as the material found to the north and to the south shows no play of colors. Large flawless masses, weighing up to 150 pounds have been found in Modoc County. Glass Buttes, two pro min e n t land marks, on the south side of the highway, some 60 miles east of Bend, Oregon, on the Bend-Burns Highway, has produced many tons of gem grade obsidian. A very fine grade of iridescent obsidian is found here. This locality is also notable for its

Early day prospecting and collecting sam· pies at the dakelte(schroecklngerlte) deposit In the Red Desert, 45 miles north of Wam· sutter, Wyoming. The secondary uranium deposit Is carried in a thick seam of crude lIypslte, showing in the horizon between the two black lines. Partly indurated arkose above and below the canary yellow uranium ore. Photo taken in Lost Creek wash, which ha,s exposed the deposit. The deposit is re­ ported to extend over some 5,000 acres. The source of the uranium has not been discov­ ered or determined. Photo by Dake in 1936.

interest as an early day munitions fac­ tory, supplying the Indians with arrow points, knives, and many tools, long be­ fore the white man appeared. The Indian must have operated this factory for many centuries. judging by the broken discards found at Glass Buttes. Quite an industry was developed. The Plains Indians had no obsidian, hence this material was traded widely by the Western aborigine, for items like buffalo robes. \Ve find this Western obsidian ill the Indian Mounds and graves of the Midwest. You may be lacking ill experience to enable your ready recognition of a valu­ able gem material when prospecting. All you need do is to bring in a sample of the material that appears to have value as a gem. A retail jeweler may not be en­ abled to tell you if it has any value or not, but take the sample to one of the many gem and mineral supply house, scattered throughout the Country. Here you may get a prompt appraisal of the value, if any, of your discovery. These firms all carry advertisements in the several gem and mineral magazines, now being cir­ culated on a National scale, including

The Mineralogist Magazine, 329 S.E. 32nd Avenue. Portland 15, Oregon.

CHAPTER THREE

The Metallic Minerals

Various minerals, for convenience of description, are usually classified accord­ ing to their properties and uses. Those which are often cut into gem stones are termed gem min era I s. Minerals from which we 0 b t a i n metallic metals, like tungsten, copper, aluminum, beryllium, lead, zinc, tin, iron, etc. are termed me­ tallic minerals. The non-metallic minerals include those which do not yield true metals, like silicon, calcium, boron, sodi­ um, lithium, graphic and a number of others. The cerium and yttrium elements comprise a group by themselves, gener­ ally referred to as the "rare earth" min­ erals or elemen ts. We a;e well supplied with some of the metallic ores like iron, but a number of them are regarded as minerals, and are in good demand at nearly all times, but more especially' in time of war. These include the chromium and tungsten minerals, both found in sizeable deposits in the United States. We are lacking in some of the vital strategic minerals, no­ tably nickel and tin. Both of these must be obtained by importation. Hence any discovery of a sizeable deposit of either nickel or tin, within the United States, would obviously be of great potential value, even if a low grade nature. Aluminum Ores. Vas t quantities of aluminum are used at the present time. This is a far cry from the day when aluminum was first manufactured in small quantities and at great cost, merely as a laboratory curiosity, when its value was greater than that of gold. Since then, manufacturing refinements, and mass pro­ duction has brought down the price to a point where many items in common use are cast or fabricated from this light weight metal. Aluminium is commonly found in vari­ ous clays, but to meet with commercial requirements, certain qualifications must be met with. Bauxite is the common ore of aluminum, mined in huge tonnages in Arkansas, Alabama, and Georgia. We have also imported large tonnages from British Guinea. Bauxite may be of al­ most any shade of color including red, yellowish, brownish, and white. It is soft ~nd light in weight. A chemical analysis is needed to determine its possible com­ mercial value.

High-grade bauxite will not "grit" be­ tween the teeth when bitten upon. Silica is likely to be one of the chief impurities of bauxite, and over 8% is likely to ren­ der it unsuitable for treatment. The ore should carryover 55% aluminium oxides, equivalent to about 30% of the metal. Some of the aluminium silicates, like dumortierite, andalusite, sillimanite, and kyanite, are valuable ceramic minerals, finding wide use in the manufacture of items like spark plugs. Deposits of these minerals may be of considerable value. Antimony. There are many deposits of antimony within the United States, but in the past few of them were worked for the antimony alone. Usually the metal was re­ covered as a by-product, in -various base metal operations, like lead and zinc min­ ing. At one time, much of our antimony was obtained from the great deposits in China. It is widely used to harden lead, and is used in bearings and type metal to a considerable extent. Stibnite is the chief source of antimony. The mineral can be readily fused, in thin slivers in a candle flame. ,Chromium. This is one of our import­ ant and widely used strategic metals. Its use in various types of stainless "steel" al­ loys. Some of these alloys carry no iron at all, but may be referred to as "steel". However, chromium added to iron, adds many important properties to iron, in­ cluding a higher fusing point, and resist­ ance to rust. In the development of mod­ ern items like the jet engine, rockets, and the like, chromium has assumed added importance, along with nickel, vanadium, tungsten, titanium, and cobalt. Chromite is the main ore of chromium. It is a dark, often nearly black colored mineral, and quite heavy to the "heft". Chromite is invariably associated with green serpentine, and the dark-green peri­ dotite rocks. It is generally found in pockets, masses, and irregular lenses. This may make mining costly and un­ certain. Chromite in the United States appears to be limited to three great ser­ pentine belts, situated in Montana, Cali­ fornia, and Oregon, Chromite is some­ times magnetic, but if not, heating in a hot flame, like a coal fire, will make it respond readily to a magnet. Chromite must be of a specific minimum grade to qualify in a commercial manner.

POPULAR PROSPECTING

Columbium-tantalum. These two valu­ able metals are often found associated in the same deposit, neatly always placer. No large deposits have been discovered in the United States. Small deposits have been found in the Black Hills of South Dakota. Industry awaits the discovery of a suitable U. S. source, as we are now wholly dependent upon foreign sources. Copper. We need mention little here about copper, for its many uses and im­ portance is well known. Various cop­ per minerals are found in a great variety of rocks, including the volcanic, sedimen­ tary, and metamorphic rocks. The chief ores of copper, are the sulphides, and these when exposed to weathering in an outcrop, will bring about extensive col­ orings, with vivid blues and greens pre­ dominating. Even the novice could hardly miss an exposure of this kind, but it is well to remember that a small amount of copper can do a lot of coloring. So color alone may not be taken as a criterion of value. Iron. In all probability the prospector is not likely to find any new commercial iron deposits within the United States. These have long since been taken up for exploitation. Weare now turning to' out­ side regions, like Labrador, for our fu­ ture supplies of iron. The great high­ grade iron deposits, mined for many years, in Wisconsin and Minnesota, will eventually be mined out. There are a number of large, but low grade iron de­ posits remaining untouched in the U. S., but at the present time it is not economic­ ally feasible to work these, when high grade ores are available (like Labrador) in great quantities. Lead. We appear to have no shortages of lead, for this soft metal is produced in a number of mining regions throughout the country, including Idaho, and the well known Tri-State district. Lead min­ erals are frequently associated with zinc and silver minerals, and it may be recov­ ered as a by-product in a silver mine. Galena is the most important ore of lead, and when pure carries 86% of the metal. It has a characteristic metallic ap­ pearance, and is quite heavy; when once seen and handled it is not likely to be overlooked or confused with some other mineral. Galena may be found in perfect cubes, of small or large size, but most often it is found in a granular form, likely to carry more or less silver, and often zinc. The cubes are invariably pure gal­ ena, not carrying zinc or silver. In the

An earlier day prospector with his field outfit. The one with the hat on is the pros­ pector. The day of the prospector with his burros, wandering across the Southwestern desert regions, in search of gold, is prac­ tically gone. The modern prospector goes forth In Jeep or car, equipped with electronic Instruments.

granular or fine compact form, galena may be intergrown with various silver, zinc, and other minerals. An outcrop of lead is not likely to pre­ sent unaltered galena. The minerals to be noted in the outcrop, are likely to be white or grey in color, and of a non­ metallic appearance, like anglesite and cerussite. Or the outcropping lead min­ erals may be gray, brownish, or green­ ish. The lead phosphate, pyromorphite, may run from white, through gray, green, brown and yellow. Any of low fusing base metal minerals of lead, and zinc may be readily identi­ fied by fusing with a blowpipe on a block of charcoal, using a small amount of sodi­ um carbonate flux. A whitish or yellow­ ish powder coating will appear on the charcoal at the point of fusion, and at a little distance will appear small metallic globules of lead or zinc. Manganese is an important metal, widely used to alloy iron for various in­ dustrial purposes. The most important deposits appear to be in foreign countries, but large deposits have been found in Montana, Minnesota. Colorado. Alabama, and Arkansas. Some of these are found as manganese iron ores. The most important manganese min­ erals are quite black in color and include pyrolusite and psilomelane. These usually

TaE METALLIC MINERALS

31

A one man mining operation in Arizona. Prospectors often find themselves in rough country. Here an asbestos and serpentine mine overlooks the Salt River Canyon in central Arizona. (Photo by Guy Ransom)

occur as an earthy mineral, soft and soil­ ing the fingers when handled. These ores often accumulate in "bogs" as the result of weathering of other minerals like man­ ga.nite. The "bog" ores are light in weight. Rhodonite and rhodochrosite are other manganese minerals, usually pink in color, and not ordinarily utilized as a source of the metal. However, these minerals when found in good color, and compact form, are valuable as gem cutting materials. A good deal of manganese has been re­ covered from the celebrated zinc mines of Franklin, New Jersey, mainly as a by­ product. Franklinite is one of the import­ ant manganese minerals at this locality. The ores of Franklin are also widely celebrated for their powerful fluorescence under the ultraviolet lamp, and many of them can be readily identified by this means alone. Mercury. This liquid metal is at its highest price in history at the time of this writing. Mercury has changed widely in price from time to time, often render­ ing mining of a speculative nature. In many mercury mines, there is a minimum cost of mining the ore, and mining can be carried on at a profit, only when a cer­ tain price is reached. For this reason most mercury mining operations have had a long intermittent history of operation. The chief ore of mercury is the red col­ ored cinnabar, a. sulphide ore. Even the novice should have no difficulty in identi"

fying this ore. The red colors of hema­ tite and other iron oxides, are wholly dif­ ferent from those of cinnabar, and when the two are once seen together and com­ pared, they can not be mistaken. Cinna­ bar, even when impure, is very heavy to the "heft" in a hand size specimen. If a rock carrying cinnabar is powdered and rubbed on a clean copper coin, the coin will become silvered or amalgamated. One of the most sensitive tests for mer­ cury; is the ultraviolet test, sensitive to less than one part in a thousand. The test is simple. The powdered ore is roasted on a small iron spoon in a bunsen flame, and held between an ultraviolet lamp (with filter and short wave length) and a screen coated with powdered willemite. If even minute amounts of mercury are present, same will appear as dark clouds on the screen. The test is conducted in a dark room. Screens of this kind are available from Ultra-Violet Products Company, South Pasadena, California. Cinnabar deposits are limited through­ out the world, and in the United States it is presumed that all the large deposits have long since been found. The mineral may be found in almost any type of rock. Practically all the cinnabar mined in· the U. S. is from California, Texas, Oregon, Arizona, and Nevada. Molybdenum has properties and uses similar to those of chromium, finding wide use in special steels and various alloys ·€>f

POPULAR PROSPECTING iron. It is sometimes found associated with tungsten. Molybdenite is the chief mineral, and the great deposits of Climax, Colorado supply much of our needs. It has also been mined in New Mexico, Ari­ zona and Utah. Small amount from Cali­ fornia are recovered as a by-product of tungsten ore. Molybdenite usually occurs in granitic rocks, or in volcanic rocks closely asso­ ciated with granite. The mineral occurs as small flakes or foliated, often in quartz veins. It has a shiny silver-grey, metallic appearance, somewhat similar to flake graphite. It is quite soft and may be readily crumbled between the fingers. Rare Earth Metals. Some 20' different metals have been termed "rare' earths". They are not necess-arily rare in their oc­ currence, but rather they are difficult to separate from their ores. For many years most of them have found only limited uses, but with the recent developments in science and industry, some of them are finding wide applications and a growing demand. Some of them are described here. Thorium has been of little value, but this radioactive metal, very similar to uranium, has assumed considerable im­ portance. While so far as can be learned, it has not yet been used for atomic en­ ergy, but it is assumed that it will be used in the future. Thorium is a constituent of monazite sands, found in various parts of the United States including North and South Carolina, Idaho, Florida, and Ore­ gon. In Oregon, The U. S. Bureau of Mines has developed a commercial m<;thod for the recovery of zirconium from the beach sands, and it is assumed other metals are recovered as a by-product. Zirconium is one of the "rare" metals to find recent important uses. Some of the domestic monazite sands carry up to about 8% thorium oxides. Separation is made by gravity washing and magnetic methods. Selenium and Tellurium, are often re­ covered as a by-product in the treatment of copper and gold ores. Selenium is find­ ing wide applications in the new minia­ ture tubes used in radio and television equipment, and many other electronic in­ struments. It is often associated with ura­ nium and vanadium ores in New Mexico and .the Colorado Plateau region. Cerium is another member of this group finding wider applications, and also recov­ ered from the monazite sands. It is used in the "flints" of cigarette lighters and radio and electronic tubes.

A small, light weight, pocket size, battery operated Geiger counter, suitable for the casual or weekend prospector. This unit is fitted with small neon blinker lights, as shown at top, and with outlet to plug in ear­ phones. It has no meter, regulators, or other convenient attachments. This type of instru­ ment is in the $30.00 and $40.00 class, and they are sensitive as instruments go.

Gallium, rhenium, germanium, indium, rubidium, and thallium may be included in this group. In all probability history will repeat itself here, and some of these elements for which we now find little use, will in the future assume considerable importance and value. Chemical and spectrographical analysis are the only reliable means of evaluating ores in this group. Silver is recovered in considerable. quantity as a by-product in the mining of various base metals, including lead, zinc, and copper. As a rule silver is found only in volcanic rocks. At the Butte, Mon­ tana copper camp appreciable amounts of silver were found only in the gossan capping the copper veins, and for this reason, Butte at one time was not highly regarded economically. Silver is usually found as a dark, nearly black colored sulphide, argentite and stephanite. In the outcrop various oxi­ dized ores of silver may be found. includ­ ing cerargyrite. the white "horn silver". Two of the richest silver camps ever known were discovered in an accidental manner when a camp fire was set over a rich outcrop, and silver nuggets found in the ashes. Silver City, Idaho, and the celebrated Barrier lode in New South Wales. Australia. were discovered in this manner. It will be seen that the light or dark colored, clay-like horn silver in an outcrop can be readily passed by for a long time, as was the case with many fab­ ulous si1v~r deposits of history. Silver may be found in association with many other minerals. In some cases the

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THE METALLIC MINERALS

33

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A portion of the "Rock Room" of Wayland W. Magee, a retired farmer of Bennington, Nebraska. Magee is a part time prospector who spends most of the summer making long field trips into the Rocky Mountain states, prospecting for uranium and thorium. Many of the samples he gathers on his prospecting tours are given to colleges to be used for teaching purposes. Magee has a light pick. up truck, fitted for his tours, and which can be used for sleeping. Many retired persons have become part time prospectors, primarily as a hobby.

silver will predominate, while in other do­ posits the silver is only a by-product. \Vhen the famous Great Bear Lake, Can­ ada, uranium deposits were first found, prospector LaBine had only silver and co­ balt in mind. LaBine had a good working knowledge of mineralogy and he was en­ abled to readily recognize the outcrop from a description he had read in an old geo­ logical report. For many years, prior to the invention of the atom bomb, these celebrated deposits were worked only for the silver, copper, and radium. The ura­ nium was waste matter and went out with the tailings. We may regard this dis­ covery made by LaBine as one of the most classical of them all, rating along with the more recent uranium discovery of Vemon Pick in Colorado. LaBine did have a good working knowl­ edge of mineralogy, and did not start out to prospect in a "blind" manner. He went to a public library and dusted off some old geological reports. In one he read of a geological exploration made by a field party some years previously into the Artic regions of Canada. He read the printed description of what indicated to him might well be an outcrop of silver­ cobalt. He set forth and did succeed in 10­

cating and staking out what later proved to be not only an exceedingly rich silver property,but still later became the sec­ ond greatest and richest deposit of ura­ nium in the whole world. The lesson here is obvious, that dependence upon blind luck is wholly unreliable. Titanium has in recent years found ever increasing applications. For a long time its most common use was as a pigment in white paint, superior to the oxides of lead and zinc. Rutile and illmenite are the two import­ ant titanium minerals, and these are in­ variably found in p I ace r deposits in greater or Ie sse r amounts, supplying more than 90% of our commercial needs. Under magnification, rutile and i11menite, if present in the placer sands, can be rec­ ognized as dark colored heavy minerals. Through methods developed by the U. S. Bureau of Mines, metallic titanium is now recovered on a commercial basis. Titanium alloyed with iron and other metals is finding many important uses, in­ cluding the very hard titanium carbide. Tungsten is one of our most important strategic minerals in time of war, but is also invaluable for numerous peace time applications. It is unique in that it is not

POPULAR PROSPECTING All tungsten minerals have a high spe­ only tougher than ordinary steel, but it will also retain its temper when operated cific gravity, and even lower grade ores at high speed, and run red hot as a ma­ will be distinctly heavy to the "heft" in chine tool. Hence this metal in recent hand size' specimens. Scheelite is generally years has served to revolutionize many light in color, almost cream-white when machine shop practices. Tungsten car­ pure, but always heavy. The iron tung­ bide for machine tools is also well known, in addition to the ferro alloys of tungsten. states are very dark in color, ranging from dark brown to quite black. They The most important deposits of tung­ sten in the United States are in Colorado, often occur in distinct crystals. A con­ Nevada, California, Arizona, and South siderable amount of the iron-tungsten ores Dakota. Small and scattered placer de­ were mined in Boulder Coun ty, Colorado posits have been found elsewhere. Tung­ during World War I. This was before the sten minerals are invariably found asso­ discovery of many of the present day ciated with granitic rocks, and since these scheelite deposits. The Colorado deposits' minerals are tough and resistant, they are are centered around Nederland. Cuproscheelite is usually greenish in often noted first' in placers, and their source traced by panning. The chief com­ color, while tungstenite may be noted as mercial tungsten minerals are scheelite, a bright-yellow powder on other tungsten ferberite, and wolframite. 'The lesser ones minerals in an outcrop. During the past include hubnerite, tungstite and cupro­ few decades a number of important scheel­ ite discoveries have been made in the des­ scheelite. Scheelite and cuproscheelite fortunately ert and mountain regions of southern are both strongly fluorescent under a California, and in all probability there short wavelengfh ultraviolet lamp. This still remain deposits to be discovered. To qualify commercially, a tungsten de­ property has proven of great utility not only in prospecting for these minerals, posit need not be "rich", since ores carry­ but also in their recovery from the ores in ing as low as 2% of the oxide are in de­ milling. So characteristic is the bluish mand, and if the deposit is a large one colored fluorescence of scheelite, that ores of 1% or less can be worked at a once noted it can hardly be forgotten. profit, as is done at Atolia, California. Moreover, any minute size fragments of Tungsten is one of our most valuable scheelite in a placer sands can be in­ common metals. stantly recognized under the ultraviolet Powellite is one of the lesser tungsten lamp. Chemical an:llysis for tungsten is minerals. It is an alteration product of slow and costly. scheelite, with some of the tungsten re­ Unfortuniately, the iron tungstates, fer­ placed by molybdenum. Powellite is seen berite, hubnerite and wolframite, never as a dull yellow powder, coating ores or show fluorescence, however they do not filling cracks and seams. It may be noted appear to be as widely distributed in the with scheelite, especially in the zone of United States as is the calcium tungstate, oxidation. Powellite has a distinct fluo­ scheelite. Cuproscheelite has part of its rescence and may be readily noted under calcium content replaced by copper, and the ultraviolet lamp. Its fluorescent color this tends to change the bluish fluorescent will be dependent upon the amount of color to a yellowish one. The ultraviolet molybdenum present, and will vary from lamp is by far the most valuable tool for whitish to a distinct yel1ow. The char­ the tungsten prospector. Portable, battery acteristic strong blue fluorescence of pure operated lamps are available for field use. scheelite will also be altered by the Sample testing under the lamp should be amount of molybdenum and copper which done in darkness, but a heavy blanket will may be present. In fact the molybdenum serve to offer darkness for daytime test­ content of tungsten concentrates may be ing in the field. A few small and typical estimated from their fluorescent color. samples of scheelite and cuproscheelite, Comparison standard color charts are purchased from mineral supply houses, available for this purpose. Even small will prove invaluable to familiarize the amounts of molybdenum will suffice to prospector with these ores. alter the fluorescent color of scheelite.

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CHAPTER FOUR

The Non-Metallic Minerals

The non-metallic minerals are those which carry no metal as such. They are more commonplace and familiar than the metallic ores, and most of them are found rather widely. There are many factors which enter into the commercial utiliza­ tion of a deposit of non-metallic mineral. These factors include quality or grade of the material, size of the deposit, presence of various impurities, economy of min­ ing, and the matter of transportation to the point of use. Thus we find many otherwise excellent deposits of little pres­ ent value owing to one or more of these factors. Competition with other deposits also enters into the picture. Non-metallic minerals include items like gravel and rock suitable for high­ way construction. In some part of the country, like the Midwest, these may not be readily found, or they may be situated at some distance and involve costly trans­ portation. Limestone rocks suitable for calcining to make Portland cement is also a valuable non-metallic. The perlite type of obsidian has in the past decade found valuable applications in the building in­ dustry. It is significant that the gross value of all non-metallic products, mined annually, exceeds the value of the metal­ lic ores. Coal and petroleum may also be regarded an non-metallics. Only the non­ metallics within the scope of the part­ time prospector will be considered here. Abrasives find wide use in many in­ dustries. While huge amounts of manu­ factured abrasive like silican carbide (Car­ borundum) are used, yet great tonnages of natural ones are mined each year. Pum­ ice, diatomite, tripoli, quartz, and garnet are among the best known abrasives. Some of these are also used as polishing powders in the metal industries. It will be seen that a deposit of a suitable abra­ sive is likely to have a wide and steady market. "Sand" papers and garnet coated papers are widely used in the woodwork­ ing industries. The "sand" type is usually coated with crushed quartz, graded to suitable grit sizes. Diatomite, also known as diatomaceous earth, is a friable, earthy material, usually whitish in color, and composed of about 90% silica. Infusorial earth and tripoli are in this classification. This material con­

sists of the silicious skeletons of minute water plants called diatoms, hence we find deposits of this nature as a sedimentary one, originally layed down in water. Some of the deposits are quite pure and of con­ siderable thickness and extent. A speci­ men of diatomite wiII float on water, while the tripoli type wiII not float, there being a slight difference in specific gravi­ ties. These material find many commer­ cial uses, including uses as water filters, and polishing agents. Tripoli is so soft it will crumble in the fin g e r s, but the minute grains are hard enough to scratch (and polish) steel. Other abrasives of commercial value in­ clude, high quartz content sands, various types of compact sandstones, pumice, and novaculite. The latter material, a com­ pact claystone is widely used as an "oil" stone for sharpening tools. Common pum­ ice finds many uses as an insulating ma­ terial, and the ground powder as a pol~ ishing agent in the metal industries. Pum­ ice is common to many parts of the West, where it was originally blown out of vol­ canoes. A chunk of pumice readily floats on ·water. Only a comparatively few of the many Western pumice deposits are suitable for commercial use. Pumice is al­ so used as an aggregate in light weight concrete. It would be difficult, if not impossible, for the prospector to determine the possi­ ble value of any non-metallic deposit when seen in the field. If a deposit ap­ pears to have value, .and a large quantity available, typical samples should be taken. The U. S. Bureau of Mines, Washington, D. C. has issued a large number of free "Information Circulars" per t a i n i n g to mos t of the non -metallics. These excellent circulars detail some of the commercial requirements for each specific material. Possible buyers are also included in most of the Circulars. Many of the s.tate mining bureaus issue similar circulars and bulletins, giving de­ tailed information on the non-metaIlics found and mined within the state. These valuable publications also list possible buyers. A list ~f possible buyers, and market prices, would soon become obso­ lete, hence they are not included in this work.

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36

POPULAR PROSPECTING

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The tendency of many prospectors has been to start a search for a buyer, with­ out first learning if the deposit they have located would hold commercial value. As a rule, buyers of non-metallics are not in­ terested in carrying on exploration or testing work. This is outside their field. Hence any work of this kind must be done by the claim holders, usuaUy at their own expense. A deposit meeting with all the commercial requirements, will usually not go begging for buyers of the property or the product of the property. Many times a prospector has come to the writer with a few hand samples, searching for a buyer, and not knowing the true nature of their discovery. This seems like get­ . ting the cart before the horse. Asbestos is used in great quantities in the United States, we have few good de­ posits of the fibrous "serpentine" type. This is the variety that occurs in compact thread-like form, and may be spun into threads and woven into cloth. One of its most familiar uses is in brake band lin­ ings. Most of our supply is imported from Canada and elsewhere. It brings a high price. Our best known deposits are in Arizona. This high tensile strength as­ bestos invariably is found in and closely associated with green serpentine rocks. The amphibole type of asbestos is a.1so found fibrous, but the individual threads are short and greatly lacking in tensile strength, and can not he spun or woven. It is of much less value than the former. Barium in the minerals barite and with­ erite, are found associated with various sedimentary deposits, including clays. The mineral barite is usually white or light in color, and quite heavy when pure or nearly so. Various impurities may render the deposit dark in color. Building stone including marhle, gran­ ite, sandstone, and various attractively colored volanic and sedimentary stones find a diversity of uses, despite active competition by various artificial building blocks in the concrete class. These arti­ fical blocks are usually made light in weight by use of light weight aggregates, like pumice, in the cement mixture. There are many deposits of suitable natural building stones, and more and more of these are being utilized, hut in all cases the economic requireml:nts are rather rigid and close. Clays are widely used in the ceramic in­ dustry, and include many types for vari­

,Bit.H.....lai" "? •G~", hUIfit"n """",-_ _-....,Clt4lCtd h~.,. right out." /

ous ceramics. Common brick clay is rather widely distributed, but the ptob­ lem is to find deposits not too far sit­ uated from where the finished product is used. Here again, transportation is an important factor. The better grades of clay are used in the manufacture of the finer ceramics. Various types of clays, like fuller's earth and bentonite are mined in large amounts. In order to determine if a clay is suitable for commercial use it must be tested by one of the many users of clay. Feldspar is another ceramic mineral, but not in the clay class. This material is mined widely in quarries, many of which are along the Atlantic Coast. Feldspar carries a rather high potassium content, and is often utilized as a source of this element. Feldspar is frequently mined in quarries in pegmatite dykes, where a host of other minerals are usually won, in­ cluding valuable sheet mica, quartz crys­ tals, and in some cases valuable gem min­ erals are encountered in the workings. Some of the New England "rock" quar­ ries have produced small amounts of pitchblende, encountered from time to time in pockets in the workings. Produc­ tion of gem stones is speculative and un­ certain, there being no way of telling where or when a valuable gem pocket may be opened. Fluorspar (fluorite, mineral name) is used in huge amounts in the iron smelt­ ing industry, where with limestone it forms a needed flux. The element fluorine

J

," i THE NON-)IETALLIC MINERALS

Many types of colorful rocks are now stones. V. P. Cutler, California collector, and well known Nevada "Wonderstone." Nevada for some years. It is '1 hard and the gem quality class. Large quantities shipped for many years.

37

being used in the building industry as ornamental hold a pair of book ends made from the colorful This ornate and colorful stone has been mined in durable stone, with the better grade passing into of this remarkable rock have been quarried and

plications. Marl is one type of limestone, i, also obtained from fluorite. Practically all our fluorite is obtained from the mines in great demand for the manufacture of portland cement. of southern Illinois, centered around Rosi­ claire. At the time of this writing, these Phosphate rock for a long time has been deposits were not active, since the min­ widely used as a fertilizer, and as a source eraI was being imported from cheaper of phosphates. Some 9 million tons are foreign sources. mined in the United States each year. Gypsum (plaster paris) is used in quan­ These deposits are of various types, and tity in many industries. The familiar pias­ the largest and best known ones cover ter board is widely used in the building great areas in Florida, Idaho, and Ten­ industry, and in cement manufacture. It nessee, with lesser extensive deposits in i3 found in large sedimentary beds, where some of the other states. The known re­ it was originally precipitated from lake serves in Idaho alone are estimated to waters, like on lake bottoms in arid re­ run into the billions of tons. gions. Its color may be snow-white or One of the most recent developments light-brown, depending on any impurities in phosphate rock in recent years, is the present. Gypsum is soft and may be possibility of the recovery of the small readily scratched with finger nail. amounts of uranium present. The uranium Limestone and chalk are also used in content may amount to only a few ounces quantity in many industries. Limestone per ton, but when the enormous tonnage is essentially a calcium carborate (calc­ is considered, this can be an important ite). A drop of hydrochloric acid applied source of valuable uranium, especially to a sample of limestone will cause it to when the deposits of the Colorado Plateau "fizz" vigorously. Chalk will not fizz, un­ become mined out. A considerable amount less a substantial amount of limestone be of research has been done in connection present, as an impurity mixture. with the extraction of uranium from this Some 200,000 tons or more of lime'stone­ rock. Feasible technical methods have are mined each year, for use in agricul­ been given for the amounts of uranium ture, chemical industry, smelters, glass recovered from this source. industry, and many other important ap­ It would not be feasible to treat phos­

38

POPULAR PROSPECTING

phate rock for its small uranium content alone. However, the crude rock is put through various types of treatment for various uses, and these include some chemical treatment. Hence, by the addi­ tion of some added treatment, the urani­ um can be recovered. It has been an7 nounced that several of the present phos­ phate plants are now recovering uranium, and additional plants will be so equipped in the near future. The prospector may well regard the potential future value of these deposits, as only a very small part of them are

now being exploited. For example, there are great areas in southern Idaho, and adjacent Wyoming, of phosphate rock of which comparatively little is known. Doubtless much of this ground is on the Public Domain, and open for mining entry. Coa1. Some of the great low grade coal deposits of the United States, carry small amounts of uranium, similar to the phos­ phate rock, these include the great coal deposits of South Dakota. Investigations now being made may reveal the coal to be a valuable future source of uranium.

CHAPTER FIVE

e Uranium Minerals

There can be no doubt that the present uranium "rush" is the greatest prospect­ ing boom the world has ever known. The tremendous interest in locating new de­ posits of uranium (and thorium) is not just confined to the United States and Canada, but is universal throughout the world. A far greater army of uranium hunters are in the field, than any gold or diamond rush of history has ever wit­ nessed. The rewards for uranium discov­ ery are just as great, as those of history. The Atomic Energy Commission has in the past decade paid out many millions for uranium ores bought in the Colorado Plateau region, in addition to added mil­ lions paid out in the form of bonuses, and substantial sums for trucking and road building aid to reach isolated deposits. In short, Uncle Sam will spend practically any sum of money to obtain the vital ore. During the past few months, Asso­ ciated Press reports have described a number of profitable uranium finds, in­ cluding the discovery of Vernon J. Pick, who was paid some $9,000,000 cash for his claims. Other discoveries are described as having a value of some $20,000,00 along with handreds of lesser valued properties, many of them in active operation. Most of these are in the Colorado Plateau re­ gion and in adjacent Arizona and New Mexico. There are still many opportuni­ ties for discovery. The universal search for uranium is not for military needs alone. It is predicted that within the next several decades our known reserves of coal and petroleum will be largely depleted, or have reached a point of depletion where we will be obliged to turn to various low grade re­ serves at a much higher production cost. It is expected that long before this. the development of atomic energy will have 'reached a stage where it can well compete with coal, petroleum, and water power de­ rived electrical energy. We are told that the present known reserves of uranium would suffice the present world needs for about a century. However, the demand for electric power is growing at a rapid rate, so that eventually even the reserves of uranium (and thorium) would perhaps not suffice. Eventually man will turn to the sun for

all his power needs-that enormous store­ house of nuclear energy that will never die. Astronomers tell us that the sun is an enormous hydrogen "bomb," not an explosive one, but a source of energy that has been constant and steady for at least 500,000,000 years that we know of, and perhaps a total of at least 3 billion years. They estimate that there is enough hydro­ gen present to keep the sun pouring out its same vast energy for at least another 30 billions of years. Man of the future need not worry about sources of power. The uranium hunter need not have any special skill or training. Vernon Pick and Charles Steen, were not geologists or mining engineers, they are in the amateur class, still they made enormously valuable discoveries, through some study, plus hard work in the field. We have called atten­ tion to the fact that a knowledge of the appearance of the common uranium min­ erals offers an enormous advantage to the prospector. Science has provided a most delicate, sensitive, and accurate instrument for the uranium hunter, the Geiger counter. Latel" developments have produced the still more sensitive scintillator, designed primarily for prospecting large areas from airplanes and truck. Both of these instruments are regarded among the most sensitive known in the detection of very minute amounts of a substance. The Geiger counter is available in many types and price classes ranging from about $30.00 on up into the hundreds, for portable battery operated field units. Lab~ oratory Geiger counters for quantitative work run into the thousands of dollars. Scintillators are more complicated in con­ struction and at the present time start at about $350.0'0 up. The average part time prospector will find a standard priced Geiger counter ample for his needs and purse. We have often been asked what type of equipment is used to prospect by plane or auto. Equipment of this kind is used by the Atomic Energy Commission and various corporations, but eqiupment of this kind is complicated and runs into the thousands of dollars to outfit a truck or jeep. More­ over, specialized knowledge is required to operate equipment of this kind. and this

40

POPULAR PROSPECTING

we feel is beyond the scope of this book, and its readers. Foot work is indicated for the prospector. In addition to a COUll­ ter, a hand size rock pick will comprise the next important part of equipment for prospecting. All uranium ores, rich or lean, off invisible particles of energy called "radi­ ations." These are given off at a constant rate, and can not be changed by any me2.ns known to science. These' radiations are picked up by the Geiger counter and scintillator, and are identified by various means, including clicks, flashes from a neon signal indicator and by meter read­ ings. Various types of instruments will have one or more means of indication, counting or recording these radiations from any tpe of uranium (and thorium) ores. When in the field, these radiations are only of an approximate qualitative nature. Quantitative tests of reasonable accuracy may be made by testing samples of the ore, in a place where the background count is known and fairly constant, and this count compared with a known stand­ ard. Invisible particles of high energy, known as cosmic radiations, constantly bombard all parts of the earth, and these are picked up by every Geiger counter.

These cosmic rays come from an un­ known source in outer space, and our sun is probably a contributor, but this is not definitely known. The rate at which these

cosmic radiations come will vary at dif­ ferent places and in different instruments, hence each Geiger counter will have a specific "background" count for anyone area, and this count is deducted from the count obtained from an outcrop in the field or when testing a sample. Samples may be best tested indoors and in the same place where the background count is known from repeated tests made and the average taken. A basement is a good place, where the background count will usually be found at its minimum. In this manner reasonably accurate tests may be made. Attention is called to the fact that a very small amount of a very rich ore, like pitchblende that runs 70% or more uranium will make any counter "run" fast. On the other hand a similar size fragment of ore running say only 0.01 % or 0.001% uranium, is likely to not even record on the average Geiger counter. However, tests may still be made on even very lean ores, but breaking up the mass, and test-

Taking a timed "station" reading of radio­ activity in the field. The earphones shown are not needed with the automatic "click" recording meter. A stop watch is used to accurately record time tests of rate at which radiations are received from an out· crop or suspected buried deposit.

ing a larger quantity say from 10 to 50 pounds or more, holding the instrument close to the sample. A large sample, even though very low grade will obviously, make up for its leanness by its bulk of

radiations,

The same facts hold true in field work.

Even a small pocket or deposit of rich ore, fairly near the surface, would register on the counter. In a similar manner, a huge deposit of a lean are would give a similar count. Uranium radiations will penetrate various depths of solid sub­ stances, but there are limitations, hence the Geiger counter or the scintillator both have their limitations as to what depth and distance detection is possible. This is why core drilling is done to prove or dis­ prove a uranium deposit. The cores are brought to the surface and tested in the laboratory. The radiations given from all uranium ores include what is called the alpha, beta, and gamma radiations. The first two are weak and of low velocity, and low pene­ tration power. The gamma rays, same as are found in X-rays, have much greater penetration powers, but still they have their limitations. In general these gamma radiations will be stopped by about three inches of solid lead, one foot of solid volcanic rock, and about two or three feet

I.

'.

'-:--_ ..

THE URANIUM MINERALS

41

A fine large specimen of the botryoidal type of nearly pure pitchblende. From Eldorado Mine, Great Bear Lake, Canada. -Pitchblende has a high specific gravity, more than three times that of ordinary rock, hence specimens of this kind are distinctly heavy when held in hand. Any black or dark colored rock, like basalt, obsidian, and furnace slag, can be readily distinguished from pitchblende by th'eir greatly inferior specific gravity.

of loose sand. rock or surface dirt. The much more powerful cosmic radiations will readily make these penetrations. . There are some exceptions to this gen­ eral rule. In the case of huge and very rich deposits of pitchblende, like those of Great Bear Lake in Canada, radiations on the surface will be detected at greater depths. Here again volume enters into the picture. Field tests of this kind involve complicated and costly testing equipment, beyond the scope of the prospector. The range of depth at which a scintillator will operate is greater than that of the Geiger counter. Here again various factors will enter into the picture like. the nature of the overburden, the size and quality of the orebody, and. most important of all is whether the overburden is radioactive. In the latter case, either a Geiger counter qr a scintillometer may then be effective in locating an orebody at a depth of a few hundred feet. But if radioactivity does not extend to reasonably near the surface, neither instrument can be relied upon. Core drilling will be indicated. The scin­ tillator is said to be about 100 times more sensitive to gamma rays than the Geiger counter. However, this need not startle the prospector, for by no means has the latter instrument become obsolete for its intended purpose and field of utility.

Basically, all Geiger counters are alike ill their mode of operation. A tube known as a Geiger tube is the heart of every in­ strument. A simple, low priced instrument has this tube. Going into the higher priced counters, various pieces of equipment are added, including meters, neon flash lights, automatic counters, and various other items, and this accounts for the price dif­ ferences, plus better types of tubes in higher priced equipment. A counter uses only small amounts of power, usually not much more than an ordinary flashlight, hence the dry power batteries will gen­ erally have long life where the counter is not operated over long periods of time. Manufacturers of various types of Geiger counters and similar instruments, issue printed instructions for use. These should be read carefully and observed.

URANIUM HUNTING Uranium ores are spotty and irregularly distributed, usually in relatively small de­ posits, and prospecting constitutes in al\ localities an important factor even after commercial development has commenced. Many of the uranium minerals are brightly colored (either yellow ore green), and even the black varieties have a character­ istic appearance, so that ore bodies are readily recognized if they outcrop. More

--.-,..-~-

42

often, however, they do not outcrop, and then the search for ore involves a careful study of the geological conditions. There are certain indications for carn­ tite, but no rule in prospecting can be given, except that good judgment might be shown in choosing a favorable loca­ tion. The erratic nature of the occur­ rences is indicated by the fact that an average of 14 per cent of the total time spent on working the claims operated by the Bureau of Mines in 1924 and 1925 was spent in search for ore. In prospecting and in delimiting ore bodies, after they are discovered, all the usual methods may be employed - test pits, tunnels, core drills, and churn drills. Even core drilling, however, is uncertain unless the holes are closely spaced, for there is usually little continuity to the deposits. Spence has stated that the pegmatitic minerals that contain uranium/thorium, Pillar in the Uranium Belle Mine, Hamm Canyon, San Miguel County, Utah. Lower in amounts ranging from small traces to portion of pillar is light gray colored sand­ substantial amounts, may exhibit a me­ stone; upper portion is thinly bedded sand· tallic or non-metallic character and ap­ stone carrying uranium and vanadium. Photo pearance. Often, it may be difficult to de­ . taken in 1921 when mine was worked pri. cide off-hand into which of these cate­ marlly for the radium and vanadium content gories a particular unknown mineral of the rich carnotite ores. should be placed, since many black species appear to be metallic, and only In dykes composed of pink or red one examination of small fragments under feldspar, the color of the spar around a strong lens or a microscope does their uranium/thorium minerals is usually of non-metallic nature become apparent. This a conspicuously darker brick-red shade; is evidenced by the fact that thin chips in white feldspar dykes, such minerals or splinters are translucent, usually ex­ often cause a brownish or black dis­ hibiting a characteristic red or brown coloration in the enclosing rock. color, even though the massive mineral Hugh S. Spence has stated that pitch­ itself may appear opaque. blende is the only u ran i u m mineral In general, it may be said that any con­ known to occur in the form of definite spicuously heavy, black or dark-colored veins or lodes. It may be difficult to minerals discovered in a pegmatite should identify with any certainty by its out­ be tested for possible uranium/thorium ward characteristics; w hen relatively content. Such minerals may be difficult pure, however, its exceptional weight to distinguish visually from magnetite serves to suggest its nature. The ab­ and ilmenite - both common in pegma­ sence of any indications of crystalline or tites - or from rare tantalite-columbite, grain structure, or of cleavage, is help­ wolframite, and cassiterite. G rea t e r ful, the mineral breaking with a smooth, weight serves to distinguish them from irregular, fracture and having a dun, black tourmaline, one of the commonest somewhat greasy or pitchy appearance dark - colored pegmatite minerals, and or lustre. It sometimes occurs in botry­ also from hornblende. oidal, or kidney - like masses, or crusts, The presence of a bright yellow or which under a lens are seen to have orange crust or powder surrounding a radiated structure. In this last form, dark mineral is almost conclusive evi­ pitchblende somewhat resembles hema­ dence that it contains uranium; and small tite iron, but it may readily be distin· plates or scales of a yellow or emerald quished from a hematite. by the black or green color on cracks and joints in a greenish black color of its streak or rock are a useful indicator of nearby powder, which for hematite are a strong primary uranium are. red.

•

THE URANJ{TM

~nNERALS

Sawed and polished section (left) of rich pitchblende ore, Eldorado Mine, Great Bear Lake, Canada. Light colored lines in the photo are veins of pitchblende, forming network around brecciated fragments of rock. AutoradJograph (right) showing association in greater contrast. The advantage in using a smooth, flat, sawed surface for taking autoradiograph is that, a sharp focus picture witl be obtained.

URANIUM GUIDE SUMMARIES Hugh S. Spence has summarized sev­ eral main points to be remembered in connection with the mode of occurrence of uranium minerals, and these are espe­ cially good for the prospector to keep in mind. He states that, broadly speak­ ing, the occurrences may be divided int the following three main types: (1) Individual crystals, or nests, pock­ ets, or similar aggregates of crystals usually of small size and extent sparsely and irregularly scattered through dykes of granite pegmatite. The variety of ura­ nium minerals occurring in this manner is large, and embraces a large portion of the known species. Distinguishing characteristics of such minerals are black color, metallic appear­ ance, heaviness, and good crystal form. (2) Veins, or lodes, of similar charac­ ter to the general run of those of other metallic minerals such as zinc, lead, cop­ per, etc. Pitchblende, the richest and commercially the most important ore of uranium, is the only primary uranium mineral that occurs in deposits of this type. It may be the dominant mineral, or, as sometimes the case, be in the nature of an accessory in veins of other metallic ores, notably those of silver, cobalt, and nickel. Pitchblende is charac­ terized by black color, metallic appear­ ance, greasy or pitchy, lustre and dense, massive texture. It never exhibits crystal

form, but sometimes occurs in layer or bands having botryoidal or kidney-like surfaces. (3) Deposits of a bedded, replacement, or stockwark character; in which the uranium minerals are a minor constitu­ ent of secondary origin and nature and have been emplaced through the agency of surface or circulating waters. Occur­ rences of this type may be found in both sedimentary and igneous (granitic) rocks, and usually they carry little, if any, trace of primary uranium minerals. Secondary uranium minerals found in such deposits are characterized by vivid and brilliant colors in tones of yellow, orange, or green. They are usually in the form of soft powder, crusts, or tufts, occasionally being more massive. They seldom ex h i bit distinguishable crystal form, except in the case of the two com­ moner s p e c i e s tobernite and autunite, which occur in small well-developed thin plates. A general summary and guide of the fluorescence characteristics of uranium minerals includes: I. Primary uraninites (pitchblende) do not fluoresce. II. A number of secondary uranium­ bearing minerals are highly fluo­ rescent, i.e., those which contain the uranyl group. In chemical tests, which alter primary min­ erals, substances are produced

44

POPULAR PROSPECTING which compositionally are analo­ gous to the secondary minerals.

III. In practically every case of fluo­ rescence the characteristic yellow­ green, or a hue of this is observed. IV. Generally, the more soluble urani­ erous minerals are those which are fluorescent. V. The largest number of fluores­ cent uranium minerals are those which have a specific gravity of approximately 3.5. Few with a high gravity fluoresce. VI. Fluorescence is best excited by short wavelength ultraviolet 'radia­ tion, e.g., wavelengths of 2537 A.V. VII. Primary uraninites after weath­ ering frequently alter to second­ ary and fluorescent species. In this way a dual detection may be made with the lamp.

PHOTOGRAPHIC METHODS The radiations from radioactive sub­ stances are all capable of affecting a photographic plate. Since the radiations penetrate opaque matter, a wrapped and undeveloped pho,tographic p I ate may serve for the detection of radium, urani­ um and thorium, as ores or other ma­ terials containing these substances will, in effect, "take their own picture." Practically any film will serve for the qualitative de t e c t ion of radioactivity, though care must be used in interpreting results. A positive test for radioactivity is not conclusive for radium and uranium. Mesothorium and thorium will also affect a sensitive plate. Tests for radioactivity will therefore s how only whether the specimen contains uranium and radium or thorium and mesothorium or all four elements. The appearance of the sample will generally indicate which of the ele­ ments are present, but in case of doubt, other more specific tests should be con­ ducted. Likewise, mas s i v e specimens may "strike" a photographic plate, giving the appearance of exposure, merely as a re­ sult of pressure. To test a sample for uranium or radio­ activity, lay the mineral to be tested on a film or plate holder containing un­ exposed film or pIa t e. If uranium is present in any considerable quantity the plate will be acted on within a period ranging from twelve to forty-eight hours, depending upon the quantity of radio-

Radioautograph of a rich pitchblende speci. men. The light colored network of lines, are small veins of pure pitchblende.

active matter in the specimen. A rich and nearly pure $pecimen of pitchblende will strike film wit h i n twelve hours, while a very lean sample like the urani­ ferous hyaline opal from North Carolina will require weeks of exposure. A metallic object like a flat' key or coin placed between the specimen and the film will appear in outline after the film is developed in the usual manner. Ir­ regular mineral specimens may be sawed to obtain a flat surface prior to exposure to film. The flat surface will' give a sharper and clearer outline of the radio­ active areas within the specimen. When large numbers of specimens are tested by the photographic method it is convenient to cut small numbers from lead foil and use these for the identifica­ tion of the plate (if affected). Likewise, in order to avoid the false effects of pressure, it is wise to support the speci­ men above the film by blocks or some other mechanical means, though permit­ ting one face of its surface to remain as close to the sensitive emulsion as possible. The ability of a radioactive mineral to strike or blacken a photographic plate varies according to the uranium and/or thorium content of the specimen. There­ fore, it can be expected that the various minerals will act differently, some pro­ ducing an image within a matter of a few hours or less, but others requiring up to several weeks to provide an effect.

ULTRAVIOLET LIGHT AND

FLUORESCENCE

If the limitations and characteristics of ultraviolet light and florescence are well understood, these methods will prove

THE URANIUM MINERALS

45

One of the dumps of the Club Camp Mine in Hieroglyphic Canyon. Lower San Miguel River, Montrose County, Colorado. Photo taken in 1921, when the workings were active, Ore was mined primarily for its radium and vanadium content. In 1921, uranium was a waste product. This mine and many others were actively worked for radium and vanadium, for some years, until the rich p!tchblende dep.osits were discovered in the Belgian Congo. The Colorado and Utah radium. uranium mines could not compete, and were closed down.

highly satisfactory in prospecting and detecting uranium minerals. They are of no value for the thorium minerals. Fluo­ rescence alone is not indicative of urani­ um, since certain non-uranium minerals will fluoresce under ultraviolet light. However, in this fact there lies a double value, since a prospector may run on to a deposit of zinc, tungsten, or other val­ ues which certainly should not be ignored. The non-uranium minerals which fluo­ resce yellow to green, as do certain secondary u ran i u m minerals, include willemite (yellow to green, with short wavelength ultraviolet), various silicas and calcites. The main ore minerals of uranium - pitchblende and carnotite-do not fluoresce un I e sst hey have been specially treated, say by f u s ion with sodium fluoride into a small bead or by all acid solution treatment. The ultraviolet lamp has in recent years proven highly satisfactory for pros­ pecting and detecting uranium in various minerals. Its values for this purpose have not been widely appreciated, since the lamp is also useful for locating and appraising such valuable commodities as zinc and tungsten, as well as petroleum.

But this overshadowing of the utility of the ultraviolet lamp and fluorescence tests for uraniferous materials no longer exists. The usual chemical and physical tech­ niques employed for uranium exploration and analysis are often time consuming, expensive and difficult to use. It is for this reason that prospectors, mining en­ gineers, chemists and physicists now very frequently rCly upon the ultraviolet lamp. Discoveries With Lamp A number of uranium localities have actually been discovered by use of the ultraviolet lamp. In other instances, the lamp proves a valuable adjunct in trac­ ing veins of primary ore by the fluores­ cence of secondary uranium minerals. Outcroppings of primary ore frequently yield to an ultraviolet inspection, since they may be covered with secondary minerals. In the Great Bear Lake regions of Canada, the secondary mineral zippeite shows the presence of pitchblende out­ croppings by its bright fluorescence. Two new regions in California have been prospected by the lamp. One of these,

4<6

POPULAR PROSPECTING

at Randsburg, yields a secondary mineral of uncertain composition, a species that is probably akin to schoepite. The Rands­ burg mineral fluoresces brilliantly, and pockets of the ore can easily be located in a pulverulant gangue earth with the lamp. The other California locality, at Darwin, provides a green fluorescent uranium mineral that has not been iden­ tified. Veins of the Darwin material can easily be followed with ultraviolet light. Dakeite was fir s t discovered near Wamsutter, Wyo., by its intense yellow­ green fluorescence. This rare species is found disseminated throughout gypsite as small particles and as small yellow­ colored nodules. Dozens of localities throughout the world have first been discovered uranif­ erous by fluorescence. These areas yield silicas and opals which have a bright yellow to green fluorescence, indicating trace amounts of uranium. The lamp is the only method known by which urani­ um can be positively identified in the silicas, since the concentration of uranium is far below the limits of the most sensi­ tive physical and chemical tests available. Last year, for example, an enormous deposit of uraniferous silica was discov­ ered near the Mutton Mountain locality, Oregon, and this discovery was directly due to an ultraviolet examination. While this silica, and others in the same class, has no commercial value as an ore, choice specimens bring high prices as collectors' items. Another i1lustration of uraniferous silica is the material found in Nevada, Colorado and Wyoming.

FLUORESCENT URANIUM MINERALS The strongly fluorescent uranium min­ erals are the uranium phosphates, arsen­ ates, sulfates and others which fluoresce with a strong yellow-green color. The uranium carbonates fluoresce more of a green color. The non-fluorescent uranium minerals usually have a drab color, often being black or brown. The fluorescent, second­ ary minerals are usually light in color, sometimes being light yellow, and gen­ erally have specific gravities approxi­ mately half of the pitchblendes. The following table lists the fluorescent re­ sponses of uranium minerals, these color values being green irrespective of the locality.

su

PROFILE OF oORMATIONS

GAMMA RAY

l~n">ITY

Radiolog of drill core, showing essential features on approaching radioactive mineral which Is not penetrated (the anomaly) and the values observed when a richer body of ore is approached and finally penetrated by the bit.

Strong Fluorescent

Autunite .................... :............. yellow-green

Beta-uranopilite ......................Yellow-green

Chalcolite (cf tobernite) ......y el1ow-green

Johannite (variable) ..............Yellow-green

Metatorbernite .......................... Yellow-blue

Dakeite ....................................Yellow-green

Torbernite .............................. Yel1ow-green

Uranocircite ............................ Yel1ow-green

Uraniferous hyalite .............. Yel1ow-green

Uranophane ............................YeHow-green

Uranopilite .............................. YeHow-green

Uranospathite ........................ YeHow-green

Uranospinite ............................Yellow-green

U ranothallite ........................................Green

Medium Strong Fluorescent

Gummite (variable) ............................. Violet

Beta-uranotile .............................. YeHowish

Uranotil ................ _........................Yellowish

Zippeite ..........................................YeHowish

THE URANll7M MINERALS

41

--------------------~--~~~-~~====~----------------~

A modern type of highly sensitive Geiger counter, compact, and light in weight. Battery operated for field use. Recording gauge and control buttons shown on Instrument.A volume control loud speaker for the "clicks" eliminates the need of earphones and blinker light. Oremaster Geiger counter manufactured by Whites Electronic Company, Sweet Home, are.

URANIUM MINERALS A uranium mineral is not necessarily an ore of uranium. Before a mineral bear­ ing uranium can be considered an ore, it must not only contain extractable quan­ tities of uranium, but also fit require­ ments common to the ores of other ele­ ments, and must be found in quantities which make working worthwhile. Of the more than 100 minerals which bear uranium, only two have been re­ sponsible for the greater part of the world's stock of uranium and vanadium. In the future this picture might be changed. but presently the ores of ura­ nium and radium are those called carnO­ tite and pitchblende. Between these two minerals--carnotite and pitchblende - there are about four principal elements, and numerous trace and impurity elements. which account for their compositions. These elements in­ clude uranium, oxygen, vanadium, potas­ sium, aside from the radium which is invariably present in more or less con­ stant ratio to the uranium. (One part radium for every 3,400,000 parts of ura­ nium after equilibrium has been reached.) Although uranium and vanadium are chemically unlike, they are found together in one of their most important ores, carnotite. Vanadium is a member of the phosphorus group of elements, and ura­ nium is more akin to molybdenum and tungsten. Geochemically, the two ele­ ments are magmatically opposed. Vana­ dium is most common in ferromagnesian rocks, while uranium minerals are fre­ quently found in granites and pegmatites.

The natural uranium oxide, pitchblende or uraninite, is perhaps the most extra­ ordinary mineral which has influenced man's history. In it uranium was first discovered, then helium, and later the radioactive elements polonium and radi­ um. Now we learn that pitchblende con­ tains traces - almost infinitesimal quan­ tities-of the atomic explosive plutonium, presently obtained only by man-made methods. And it goes without saying that the world's source of still another atomic power yielding element, uranium 235, lies in the natural sources of urani­ um like pitchblende.

CARNOTITE Carnotite is found in a number of localities in the world, and in the United States outside of Colorado and Utah, but the latter deposits are the only ones which have been commercially worked. Prior to the discovery of rich uranium ores elsewhere, the Colorado - Utah de­ posits were mined extensively, primarily for their radium content. Carnotite is a potassium uranium vanadate which is orthorhombic, but most often found as a yellow amorphous powder, it is yellow and may be tinged greenish or have brown iron stains; in­ frequently dark brown to blackish due to organic material, H. 4. G. 4.1. Both hardness and gravity vary widely, ac­ cording to the purity of the specimen; thus, H. 2-2.5 and G. 3.5-3.9. Typical analysis of carnotite from Montrose County. Colo., gave 54 per cent uranium oxide and 18 per cent vanadium oxide.

POPULAR PROSPECTING

Contains an average of 3,4 parts radium per 10 million parts uranium. The potas­ sium in carnotite may be substituted for by calcium, giving "calciocarotite" which is better known as tyuyamunite, and this is related to another derivative, rauvite, a hydrous calcium uranium vanadate. Carnotite is found in a number of lo­ calities in the world. Often found as loosely cohering masses mixed with quartzose material, not infrequently re­ placement in organic material like leaves and logs.

PITCHBLENDE The known deposits of pitchblende, sufficiently rich and extensive to be com­ mercially exploited are relatively few. It is true that pitchblende and the uraninites are rather widely scattered throughout the world in small amounts, but in gen­ eral these are of less importance from a commercial standpoint than the "big three" Canada, Belgian Congo and Czechoslovakia. The Canadian pitch­ plende is the richest known considered as tonnage grade ore. The Great Bear Lake deposits are also thought to be the most extensive known; at least this' was true until 1941. The actual extent of the Great Bear Lake pitchblende deposits has not been completely divulged, and will probably remain secret for some time to come. In the uraninite group are included such amorphous or crystalline varieties of uranium oxide as Pitchblende, Cleve­ ite, Nivenite, Broeggerite. The terms "pitchblende" and "uraninite" are often used synonymously, but the term "pitch­ blende" is applicable only to the impure, amorphous form of the mineral which often has botryoidal surfaces with a con­ choidal fracture. Uraninite is isometric, in octahedrons, sometimes with dodeca­ hedral faces. Infrequently found in cubes

wit h octahedrons and dodecahedrons. Uraninite crystals are rare. In the massive for m (pitchblende) uraninite may be found in broken part­ icles cemented in matrices of various materials, also botryoidal or reniform, having a banded structure. May be den­ dritic aggregates of small crystals; also colloform. Brittle, with uneven to conchoidal frac­ ture, H. 5-6 average about 5.5 in high grade specimens. G. 9.0 9.7 for most specimens contammg admixed earths, ranging upwards to 10.63 (Chihuahua, Mexico), but as low as 6.4 with massive altered forms. Natural crystals, G. 8.0­ 10.0 (uraninite; coil 0 for m varieties (pitchblende), G. 6.5 - 8.5. Calculated on the basis of uranium dioxide, G. 10.88. Uraninite is always more or less oxi­ dized, and with increasing oxidation, the gravity drops markedly. Gravity is like­ wise decreased when the uranium is sub­ stituted by thorium and rare earths. Luster submetallic, sometimes greasy or pitch like (hence the name "pitch­ blende"), and dull. Opaque. Color drab and usually dark: deep steely or velvety black, brown - black, greyish, greenish with similar streak. In very thin splinters the high grade material may be translu­ cent on the edges. Polished surface may be pale grey, with brownish tinge. Natural uraninite, pitchblende and other varieties always more or less oxi­ dized. In face an outcropping may be greatly altered because of this property. Actual composition variable. Theoretic­ ally given as a uranate of uranyl (U,O.) or an uranium dioxide (UO,), but natural material ranges between these two in composition, with tetravalent uranium prominent. Thorium and the rare earths may be present in varying amounts, the former as high as 14 per cent, the latter mainly of the lanthanum and yttrium

r

.' THE URANIUM MINERALS

Cake examines the old bullet holes, made some 70 years ago during the "battle of The Post Office" in S.E. Oregon. The ruins of an old stage station, and oombination post office, store, stable, hotel, saloon, and gambling hall. The faintly legible insoription on the door, reads "Post Offioe - Store." This region of Harney and Malheur Counties in S.E .Oregon. comprising some 20,000 square miles, much of it Public Domain, is one of the last frontiers for gem and uranium hunters.

groups. Pitchblende contains little or no thorium dioxide and little or no rare earths, with water often present. May also contain lead, zirconium, nitrogen, helium, argon, and metallic sulfide im­ purities from association in metalliferous veins with the sulfides of Ag, Pb, Co, Ni, Fe, Zn, Cu, and others. Approximately 125 uranium and thori­ um minerals have been described in the mineralogical literature. The greater part of these have been found only in small amounts, and often at only one or a few localities in the world. Hence there are only a comparatively few uranium and thorium which are of present concern and importance in supplying the much needed uranium. The more important uranium minerals are described here in some de­ tail, while those of mainly academic in­ terest are merely enumerated. In some instances the species standing of some of the more obscure uranium minerals are in question. In some in­ stances, a uranium mineral described as a new species, has been later found to be

identical with some other previously de­ scribed species. In other cases some have been later shown to be mixtures of pre­ viously described minerals. Some of the more important thorium minerals are here included since they are radioactive, and thorium being similar to uranium, it is quite possible that in the future thorium can and will be used as a source of atomic energy, the same as uranium. At present, pitchblende and carnotite, have contributed practically all our ura­ nium. Since there are comparatively few of these deposits of any great tonnage, it is obvious that eventually we shall be obliged to seek other sources. There are great known deposits of quite low grade uranium ores, which at present are not economical to operate on a commercial scale. Present technical methods for ex­ tracting uranium from the very low grade ores, would prove prohibitive from a cost standpoint, in the face of competition of the better grade ores. In all probability with future improvements in refining technology, and by force of necessity. we

50

POPULAR PROSPECTING

will eventually turn to the very low grade uranium ores. There are three general types of radio­ active, i.e., uranium and thorium bearing minerals: (1) The primary uranium min­ erals or uranites, (2) the secondary ura­ nium minerals and (3) the so called "complexes," columbium-titanium tanta­ lates of the rare earths, uranium and thorium, including silica. Type 1. The uraninites, which are the richest in uranium, including such crys­ talline varieties as broeggerite, deveite, and certain uraninites found in the United States and East Africa. These varieties occur in pegmatites in well developed crystals, though these crystals rarely. exceed two centimeters in diameter. Pitchblendes are amorphous uraninites, and they occur in metalliferous veins, especially associated with sulfides of sil­ ver, lead, nickel, zinc, and other' heavy metals. The terms "uraninite" and "pitch­ blende" are often used synonymously, but the term "pitchblende" is applicable only to the impure, amorphous form of the mineral, often with botryoidal sur­ faces and a conchoidal fracture. Uranin­ he; when crystallized, belongs to the isometric system. It is black or grayish­ black in color, often with a glossy or pitchlike luster. The hardness is approxi­ mately that of steel (5.5). Its specific gravity is often high (5 to 9.7), according to its purity. The composition is some­ what indefinte, and it is usually described as a uranate of uranyl, together with variable quantities of lead, calcium, iron, copper, bismuth, thorium, zirconium, and other rare and common elements. Type 2. The various secondary ura­ nium minerals include phosphates, car­ bonates, arsenates, sulfates, silicates, vanadates, and uranates. Most of these are charcateristically colored bright green or yellow. The most important are autunite and carnotite. Formed relatively recently, these secondary minerals have not reached equilibrium (1 Ra :3.4 million U). The uranium-radium ratio, therefore, may vary over fairly wide limits. ,Carnotite is an amorphous, soft, pow­ dery material, occasionally talcose or waxy in character. The color is generally brilliant canary yellow, though it may be discolored by iron, organic matter, or other substances. It is essentially a hy­ drous potassium uranium vanadate, some- . times associated with the hydrous calcium uranium vanadate, known as tyuyamunite.

Carnotite is the principal ore mineral in the United States and tyuyamunite is found in Russia. Autunite is a phosphate of uranium and lime, containing as much as 50 per cent of uranium. The color is described as greenish - brown to sulfur­ yellow. It is soft (hardness 2 to 2.5) and rather light (specific gravity 3.5 to 3.9). Torbernite is a green colored mineral of similar composition, containing copper instead of calcium. Type 3. The columbium-titanium tan­ talate complexes include betafite, sami­ resite. ampangabeite, euxenite, blom­ strandite, samarskite, fergusonite, and other minerals. These substances have rather common characteristics and are easily recognized because of their high density (over 4), black or dark brown color, and greasy, brilliant fracture. Min­ erals of this group were first discovered in Norway and Greenland (euxenite, blomstrandite, samarskite. and ferguson­ ite). Later a deposit of euxenite was found in Brazil, but now by far the most important deposits are those in Mada­ gascar, which furnish several unique varieties, notably betafite, samiresite, and ampangabeite, all of which are rich in uranium. Certain minerals of this group contain thorium in varying amounts, and the radium extracted from them may contain substantial quantities of meso­ thorium. The following are the more important or the better known-uranium and thorium minerals. AUTUNITE. A phosphate of uranium and calcium. A strongly fluorescent, sec­ ondary uranium mineral, often formed in the alteration of pitchblende. Hence we may find this lemon - yellow, pulverent mineral appearing in outcrops of pitch­ plende or other rich uranium minerals. When pure or nearly so, it contains ap­ proximately 60 per cent uranium oxide, hence this mineral would be of consider­ able commercial value if found in any quantity. In the United States it is often found in the granite pegmatites associ­ ated with pitchblende. Its powerful fluo­ rescence and bright color serves to iden­ tify it, without the aid of the Geiger counter. CALCITE carrying small amounts of uranium, as an "impurity," have been found at many localities throughout the United States. Under this heading we may include aragonite and quartz (agate and chalcedony included). :The amount of uranium present in these mirterals, as

~".

THE URANIUM MINERALS

51

Prospecting trails lead one to many romantic places in the Western States-old deserte.d mining camps, now known as ghost towns. Part of what was once the main street of Aurora, Nevada, is shown here. Impressive two and three story buildings once dominated Main Street, in this city of 10,000 population when it was booming. Tall sage brush now lines this street where once stamped the hordes of eager gold seekers. (Photo by Guy Ransom).

extraneous matter, is usually very small, generally less than 0.001 per cent. More­ over, the identity of the included uranium mineral is usually unknown. However small the quantity of included uranium may be, it is usually enough to make this uraniferous calcite, aragonite, or silica, strongly fluorescent under one of the ultraviolet lamps. In view of the fact that the material is fluorescent, we would assume that the included uranium mineral is one of the several secondary fluores­ cent uranium minerals. While these uraniferous minerals are usually found in granite rock regions, known to be abnormally high in radio­ activity. This is especially true at many localities in Wyoming where we find a number of common minerals showing strong fluorescence, due to included ura­ nium. These items may include opalized wood, agate, common opal, jasper, and the like. Or uraniferous agate may appear in regions not specifically high in radio­ activity, like the southern Wasco County locality in central Oregon. Usually this type of uraniferous mate­ rial will fluoresce best under short waves, and often of a characteristic yellowish­ green. Specimens of this kind are found widely distributed in the United States,

mainly in the western states. In all proba­ bility minerals of this type are deposited by percolating waters passing through abnormally high content uranium country rock, thus picking up abnormal amounts of uranium to be redeposited elsewhere. So far none of these minerals have been of any commercial value, owing to their low grade nature. However, they may be an indication that somewhere in the vi­ cinity, and perhaps at some depth, there many or may not be a rich body of "mother" uranium. D A K E I T E. Originally (1937) de­ scribed as a new species. Since then it has been shown to be identical with the previously des c rib e d schroeckingerite, Found only in the Red Desert, 40 miles. north of Wamsutter, Wyoming, where it occurs over a wide area as yellow nodules and lumps in impure gypsite clay. This yellow sulphur-like mineral is strongly fluorescent under all types of lamps. FERGUSONITE. A columbate-tanta­ late of rare earths, with small amounts of uranium. Resembles pitchblende in both color and specific gravity. GUMMITE. One of the important and most widely distributed alterations prod­ ucts from the weathering of pitchblende. It is usually of varying composition and

": "j

52

POPULAR PROSPECTING

color, but usually deep red or reddish· brown. It is usually found as an amor­ phous gum-like substance, hen c e its name. The name has been applied to sev­ eral varieties of similar uranium minerals. When present in an outcrop of pitch­ blende, its vivid color serves as a ready identification. METATORBERNITE. An alteration product derived from torbenite. Fluo­ resces a characteristic bluish-yellow col­ or, and may be found associated with pitchblende. Fluorescent metazeunerite has also been described as a rare mineral. MONAZITE. This unique mineral is found widely distributed, and often ill ~arge deposits at various localities, includ­ mg the beach sands of North Carolina, Brazil, India and elsewhere. It is impor­ tant for its contained rare metals and thorium content, the latter being va;iable. If and when, thorium becomes important in atomic energy, great quantities of this element would be available in the sand deposits at many localities. Monazite is regarded essentially as one of the many rock forming minerals, from whence it originates in the sands. SAMARSKITE. One of the rare earth minerals carrying uranium, columbates and tantalates. The uranium content varies, averaging approximately 10 per cent oxides. Its colors and appearance and weight are similar to those of pitch­ blende. TANTALITE. While not essentially a uranium mineral, it may show radio­ activity, due to included uranium or thorium. It resembles pitchblende in most of its physical properties. THORIANITE. One of the rare earth minerals carrying various amounts of thorium, or the thorium may in part be replaced by uranium. Alters readily to gummite-like minerals. It may be found as dark colored, heavy pebbles, in placers. It may be mistaken for pitchblende. THORITE. A thorium silicate, brittle, usually black in color, and quite heavy. It may appear orange in color, when it is referred to as orangite. When pure it carries up to 72 per cent thorium oxides. The uranothorite variety ranges up to 10 per cent uranium content, the uranium replacing some of the thorium. Thoro­ gummite is another alteration product. TORBERNITE. A copper uranium phosphate, found rather widely distrib­ uted in uranium deposits, or in granitic formations carrying pockets of pitch­

bien de. It is usually brieht green in color, and fluoresces' strongly with a greenish­ blue color. Torbernite is generally found as small masses of a pulverent nature or loosely compact. URACONITE. A uranium sulphate said to be similar to or identical with zippeite, and also strongly fluorescent. URANOCIRCITE. Similar to autunite, and also brightly fluorescent. The follow­ ing "urano" minerals have been found to be fluorescent, but some may be identical with other uranium minerals, uranochal­ cite, uranophane, uranopilite, uranospath­ ite, uranothallite, uranotile. . ZIPPEITE, A uranium sulphate, carry­ lI1g about 68 per cent uranium oxides, yellowish in color, and strongly fluores­ cent. I t has been found at various locali­ ties throughout the world, but its most interesting occurrence is at Great Bear Lake, where it is not found in the work­ ings, but appears on the pitchblende ore dumps when the ore is piled in the open waiting summer shipment. This is a good indication of how quickly alteration may take place in a uranium ore. Zippeite is also found associated with some carnotite deposits, in which case the former could be readily identified by its fluorescence. The following uranium and thorium minerals have been described at various times in the mineralogical literature. So far these have been of minor interest in the uranium picture. These will be found described in standard works like the Dana Textbook of Mineralogy, and the Dana, System of Mineralogy volumes. The species status of some are in doubt. Bassetite, Besquerelite, Betafite Bran­ nerhe, Broeggerite, Clarkeite, Cleveite, Coracite, Cyrtolite, Dewindite Dumonite Eliasite, Ellsworthite, Eucras'ite, Euxen~ ite, Fourmarierite, Gadolinite Gilipinite Hatchettolite, Hyblite, Lanthi~ite Ishika~ waite, Johannite, Kasolite, K~tangite, Lambertite, Liebigite, Medjidite, Nastur­ an, Parsonite, Phosphuranylite, Pyro­ chlore, Randite, Rauvite, Renardite, Row­ landite, Samiresite, Schoepite, Sengierite, Sharpite, Soddyite, Thucholite, Troeger­ ite, Volglianite, Volgite, Walpurgite Xenotime, Zeunerite. '

URANIUM DISCOVERIES There are a large number of known occurrences of uranium and thorium minerals in the United States, but the carnotite deposits of Utah and Colorado are by far the best known. Pitchblende and its alteration products are widely dis­

THE URANIUM MINERALS

53

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tributed in small amounts, notably in the pegmatites and granitic rocks in the New England states, North and South Caro­ lina, Texas, the Rocky Mountain states, and elsewhere where rocks of this type occur. In most cases the uranium minerals are found as small isolated pockets, en­ countered during quarrying operations or mining other minerals. Often these pock­ ets produced excellent specimen material, and much of this pitchblende and the associated secondary uraninites found its way into private and public mineral col­ lections. All known types of rocks are radio­ active to some extent, but in some parts of the United States, there are great areas where the country rock is abnor­ mally high in radioactivity. This is es­ pecially true of much of the rocks of Wyoming. Percolating waters passing through country rock of this type fre­ quently leach out enough uranium to render various silicious minerals strongly fluorescent. There are great areas in Wyoming ;'''{here I a r g e deposits of chalcedony, agate, common opal, and silicified woods carry very small amounts of secondary uraninites, but enough to render them highly fluorescent - showing the charac­ teristic yellow-green of uranium. De­ posits of this type have been noted in Oregon, New Mexico, Georgia, and else­ where. Aragonite and calcite may also present a strong fluorescence, account­ able for on this same basis. Arizona Uraninite has been reported at the Happy Jack mine, Wrightson district, Santa Cruz County. In Mohave County, it is of interest to note that gadolinite is found in the Aquarius Cliffs in pegmatite, 30 miles south of Hackberry and near Kingman, about 6 miles west of Chin Lee Valley and 2 to 4 miles south of the Utah state line. Thousands of pounds of gado­ !inite have been gathered from drifting sand dunes by the Indians and some fine gems have been obtained. Gadolinite is also found here and elsewhere with peridot. Early in 1948 an effort was made to realize the value of the carnotite situated on the Navajo Indian Reservation, where also vanadium was to be extracted. The Indians were to obtain a 10 per cent roy­ alty on all mineral compounds except the vanadium.

A popular field type, battery operated, Geiger counter, manufactured by Fisher Re­ search Laboratory, Palo Alto, California. The instrument may be used with or without the light weight probe or prospecting stick shown In the photo. Geiger counters are also invaluable for testing suspected uranium specimens. By the use of known percentage uranium specimens, approximate quantita­ tive work may be done on samples.

According to the Arizona Department of Mineral Resources, in a 1948 report by Chas. H. Dunning, there is an extensive uranium deposit located in Hack's Can­ yon, 37 miles southwest of Fredonia. The uranium mineral appears to be torbernite or metatorbernite, and the ore assays up to 2.50 per cent uranium. The property has been worked siuce W odd War I, for copper, and the uranium was discovered by fluorescence under ultraviolet light. The mineralized area constituting the uranium deposit is at the contact of the Coconino Sandstone layer of the Grand Canyon Series, and the underlying bed of Hermit Shale. Details of this occurrence are hidden by the talus fill along the can­ yon wall, but there has evidently been considerable displacement because the mineralized rock in the mine is distinctly Coconino Sandstone but occurs at a level below the normal floor of that bed­ where the Hermit Shale should be. The ore-rock is a typical fine grained white sandstone. Many authorities con­ sider this layer of the Coconino Sand­ stone as being aeolian or wind blown. Copper carbonates and silicates appear

54

POPULAR PROSPECTING

irregularly in the seams and are dissemi­ nated. The fluorescent mineral mentioned has not been determined for certain. It fluoresces like willemite but no such mineral can be observed and a spectro­ graphic analysis shows no zinc. It could be a calcitic coating on some of the sand grains, but is more probably an opalitic type of sand. In any event it seems to have no bearing on the uranium content and is of no economic importance. Torbernite or metatorbernite (copper uranium phosphate), an apple green min­ eral of platy appearance, appears in the seams and disseminated throughout the groundmass, and as a cementing material holding the fragments of brecciation. It no doubt accounts for a large portion of the general uranium content. Arkansas About 0.5 per cent of thorium and 0.1 per cent of uranium are reported to ac­ company the titanium ore, which has recently been found in an almost inex­ haustible deposit, Howard County. California Few uranium minerals have been re­ ported in California. Uraconite occurs as coatings in the Rathgeb mine, near San Andreas, Calaveras County. Uraninite in acicular crystals has also been noted in the Rathgeb mine. Melhase has reported well-formed crystals of xenotime, in the Southern Pacific quarry n ear Nuevo. Autunite occurs in the Summit Diggings near Randsburg. Yellow autunite as­ sociated with green plates of torbernite was reported from a locality in the north­ eastern part of San Bernardino County. An interesting uranium mineral has been recently reported from the Rands­ burg district, tentatively identified as schoepite. The mineral is highly fluores­ cent and found in an eight foot outcrop­ ping. The mineral occurs as a thin film of very small grains, yellow in color. Optical and crystallographic data are incomplete at this time; the find may represent a new species. In 1948 uranium "in hopeful quantities" was reported near Beaumont, in Mar­ shall Canyon. The discovery occurred on a 300 acre ranch, and the material is stated to be ore grade. Colorado Carnotite is by far the most important uranium bearing mineral found in the United States. The large deposits which have been exploited commercially are in

Utah and Colorado. Carnotite mining had been carried out in Colorado on a small scale, even before the discovery of radi­ um. Parsons records that in 1881, Andrew J. Talbert mined some of the ore, mainly for its small gold content. In 1911 Joseph M. Flannery, of Pitts­ burg, organized the Standard Chemical Co., to exploit the carnotite deposits for 'their radium content, and as a' by-product they contained vanadium. In the earlv days the U. S. Bureau of Mines carried out a considerable amount of pioneer work in the study of these ores, and in field investigations, notably under the direction of Frank L. Hess. Various private operations were carried on over a period of years, until 1921, when domestic production of radium salts reached its peak. In 1923 the Standard Chemical Co., largest American producer, treated only the stock pile of ore on hand in its re­ duction plant, and assumed the agency for the distribution of Belgian radium in the United States. The principal productive deposits in Colorado and Utah are all of carnotite; roscoelite, Gypsum, copper carbonates, and rare vanadium minerals mav be as­ sociated with it. The carnotit~ occurs chiefly in sandstone. Sometimes it im­ pregnates the sandstone, but it is likely to be concentrated along the cracks or bedding planes or in pockets, where it may be accompanied by petrified wood, bones or other more or less fossilized organic matter. Carnotite also occurs in New Mexico and Arizona. The deposits in both these states, though largely unde­ veloped, may be of considerable im­ portance. Smarskite, gadolinite, and allanite have been noted near Devils Head, Douglas County, Colorado. Radioactive zircon and columbite occur on Elk Creek, EI PasO' County, as do xenotime and zircon at nearby localities, e.g., St. Peter's Dome. Uraninite is found in the Gregory dis­ trict, about Black Hawk, Gilpin County; also a Domingo Mine in Gunnison Coun­ ty. Columbine has been reported in Jef­ ferson County. Colorado has also pro­ duced pitchblende, to the extent of per­ haps 150 tons or more of low-grade ore, mainly from Gilpin County. During the past few years a consider­ able number of isolated deposits of car­ notite have been discovered in Colorado and Utah. These vary greatly in size and extent and may be largely regarded as "pockets." Frequently these are worked

THE URANIUM MINERALS

General view in Hack's Canyon, Arizona, where a discovery of uranium has been made. This photo is typical of the uranium regions of Colorado, Utah, Arizona, and New Mexico. Lighter colored strata, near center line, is Cononio (Permian) sandstone. The strata below that which erodes in a more slanting manner is Hermit (Permian) shale or Supai Formation.

by small independent operators, and in some cases as "one man" projects. The ores which are extracted are sent by truck to one of the several large ore treatment plants which have been set-up in the carnotite areas. The treatment plants, in­ >"olving huge investments, are operated by large private corporations. The ores treated are paid for on a basis of uranium and vanadium content, as indicated by the A.E.c. Prospecting is encouraged, and when a suitable deposit is located and proven, financial aid can be readily obtained. Recent advances in treatment technology enables the eco­ nomical handling of quite low grade ores. The scope of these advances will un­ doubtedly be extended in the futUre, as considerable sums are being constantly expended in researches to this end. A considerable amount of literature on uranium in Colorado and adjacent re­ gions, has been issued by the U.S. Bureau of Mines and the Atomic Energy Com­ mission. These agencies also carryon air and ground surveys of various regions in the Colorado Plateau. Printed bulletins and papers are issued from time to time to keep the prospector informed. This liter­ ature is available direct from the Atomic Energy Commission, G ran d Junction, Colorado, and the U.S. Bureau of Mines, \Vashington, D. C. Connecticut The Branchville locality is famous for its uranium minerals, the s e including uraninite, autunite, gummite and tober­

nite. Columbite is also found there .At Hales' quarry, Glastonbury, and at Willi­ mantic, as well as Middleton, uraninite is also seen. Monazite is found at Nor­ wich, Portland, Watertown (near the Naugatuck), and Willimantic. Columbite is observed at Glastonbury and at Mid­ dletown. Pitchblende has been described from several quarries at Middletown, Glaston­ bury, and Branchville. Many of the fine rich specimens of pitchblende, uraninite, and various secondary uranuim minerals found in the pegmatites of the New Eng­ land States have foqnd their way into mineral collections, both public and pri­ vate. Georgia Radioactive minerals have bee n re­ ported at a number of localities within the state of Georgia. Uranophane is found in joints of granite at Stone, De­ kalb County; it is coated thinly by hya­ lite, the uraniferous and highly fluores­ cent common opal of Stone Mountain is ,vell known. Xenotime occurs at Clarks­ ville, Clark County; allanite is found in Lumpkin County. Idaho A number of uranium and thorium minerals have been found in the state, mainly as small fragments found in the placers operated in the central part of the state. The new mineral brannerite, carrying over 50· per cent uranium and thorium oixdes, was found in a placer operating in the Stanley Basin region,

56

POPULAR PROSPECTING

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and described by Hess and Wells in 1920. The bed-rock in the basin is said to be granite cut by pegmatite dikes. The bran­ nerite is doubtless derived from the peg­ matites. The radioactivity of the mineral varies with the specific gravity. the higher the gravity the greater the radio­ activity. Fergusonite, columbite, and samarskite have all been recovered from the placer dredges operating near Idaho City, Boise County. Only small amounts have been recovered. Aeschynite and Cuxenite oc­ cur as small water worn pebbles at vari­ ous localities in central Idaho. From placer concentrates obtained near Center­ ville, Boise County, Hess has reported water worn pebbles and crystals of poly­ crase, some reaching a diameter of one half inch. The mineral is also found at Idaho City. Thoruim b ear i n g monazite sand is abundant at more than 30 localities in 10 counties in Idaho. The Idaho monazite is probably lower in its thorium content than similar sands from Brazil and North Carolina, but with the increasing demand for cerium metals and the utilization of thorium as a source of atomic energy, the Idaho deposits are of potential im­ portance. The monazite is derived from the granitic rocks of the great central Idaho batholith. The main monazite localities of Idaho are as follows: Ada County. occurs in black sands at Boise and Boise Basin; Adams County, Meadows, Snake River, and John Day Creek; Boise County, has been mined at Centerville, and is found in placers near Placerville, Idaho City. and elsewhere; Canyon County, Payette River; Clearwater County, Orofino, Dent, and elsewhere; Idaho County has the best deposit at Warren district (placer); L e m h i County. at Leesburg; Lincoln County, at Minidoka; Nez Perce County, Musselshell Creek, 28 miles east of Greer, and 10 miles from Weippe; Owyhee County, at Oreana. lJrnaphane has been found in Boise County, at Carterville. ' A number of new and promising ura­ nium finds have been recently made in the state. Maine 'C"raninite is found in the pegmatite minerals of Black Mountain, Rumford. It is observed as minute crystals in and on c1eavlandite in the form of dendritic growth. Some of the uraninite has altered to gummite, autunite, uranophane and

other secondary uranium minerals. Cyr­ tolite, an alteration product of zircon, is found as small well-formed crystals em­ bedded in feldspar, assocated with the uraninite and manganese dioxide. Massachusetts Autunite occurs at Chesterfield, alollg with columbite, and numerous rarer ac­ cessory minerals. Allanite is found at Athol, Belcherton, South Royalston, and Bolton. Columbite is observed at Bever­ ly and at Northfield. Rockport has been reported to yield both fergusonite and cyrtolite. Montana Monazite has been found in the black sands at Princeton, in Granite County; also, Madison County, at Norris; and, in Powe!1 County. Thorianite has bee n known to ccour at N orris, in Madison County, for many years, but apparently has never been mined. Nevada Carnotite has been found on )01l1t5 in gold ores in the Atlanta Mine, Lincoln County. Southwestern N e v a d a yields some fluorescent opal and silica. Mona­ zite Occurs in the black sands at Carson City, in Ormsby County. There is ura­ nium in Lincoln County, 50 miles ~orth of Pioche, where it occurs with vanadium in an unidentified mineral resembling carnotite (tyuyamunite).

New Mexico Samarskite is found in a pegmatite dike, some ZYz miles southwest of the village of Petaca, in the north-central part of New Mexico. Radiographs have shown that the mineral is composed of not one, but two species. Before 1924 no uraninite or its alteration products had been found in this region, but in 1928 grains of uraninite were observed in peg­ matite dikes, ranging from 2-4 millimeters in diameter. These were accompanied by alteration products, namely, gummite and uranophane in what is known as the Frid­ lund dike. Metaborenite is found at a locality near Silver City. It fluoresces a bright green, and occurs disseminated as minute green­ ish plates in a nonfluorescent matrix. Autunite occurs sparingly in some of the ores of the White Signal district, Grant County; museum specimens are found in the Sylvanite district of Hidalgo County, and in the San Lorenzo district of So­ corro County. Carnotite is a relatively rare mineral, except in Colorado and Utah. It is found

, THE URANlL'M MINERALS

57

A broken axle can mean real trouble for the prospector far out on the rolling sage cov­ ered hills of Nevada. The old model A Ford shown here was one of the most reliable carll for the prospector, until the introduction of the modern 4·wheel drive Jeep.

in small amounts at a few localities in the state. Cyrtolite was reported from a locality southwest of Las Vegas in San Miguel County. Cyrtolite is an ill-defined species, and is possibly an alteration product of zircon. Fergusonite from the Fridlund dike, 2Yz miles southwest of Petaca, was described by Hess and Wells in 1930. Gummite as­ sociated with uraninite was also found in the Fridlund dike. Monazite carrying an average of 0.1 per cent uranium oc­ curs in the Petaca area. Samarskite in fine large specimens occurs in the Frid­ lund dike. Pitchblende and uranophane occur in the Black Hawk district, Grant County, and in the Petaca district, Rio Arriba County. New York The magnetite mines in the Adirondack region have yielded some excellent speci­ mens of allanite. This species is also found in abundance in the Smith mine, Mineville, in Essex County; also spar­ ingly at the Bedford feldspar quarries in \Vestchester County. Cyrtolite has been mined and utilized from the latter lo­ cality. Uranothorite has been observed at Port Henry. Other species which have been reported in various N ew York lo­ calities (by Manchester) include allanite, columbite, gummite, monazite, thorite, torbernite, uraconite, uraninite and xeno­ time. Pitchblende is found near Peek­ skill.

NGrth Car()lina Pegmatite formations are common to both North and South Carolina, and as ill the New England States, va rio u s uranium and radioactive minerals are found, usually in limited amounts in these formations. Generally the "pockets" and limited areas of the uranium minerals are encountered during mining or quarrying operations. Small amounts of pitchblende and its alteration products have been pro­ duced for many years as a by-product of the feldspar and mica mines. Rare radioactive minerals have been found in varying quantities widely dis­ tributed in North Carolina. The state has yielded large am 0 u n t s of monazite, among others. Monazite is found in Alex­ ander Co u n t y, at Brindletown, Burke County, in the placers with malacon, xenotime, columbite, cyrrtolite, ferguson­ ite, allanite and thorite. This locality has produced xenotime crystals an inch across, of a sage to grass - green color. Hydrofergusonite and samarskite are also found. Columbite and autunite are found in Alexander County; allanite at Balsam Gap Mine, Buncombe County; columbite ill the same county; large masses of monazite associated with zircon in Madi­ son County (Mars Hill. In Henderson County, at Green River, on the south side of Blue Ridge, there occur allanite, auerlite, polycrase, zircon, monazite,

, 58

POPULAR PROSPECTING

xenotime and crytoliteo Iredell County yields allanite (Statesville); Mecklen­ burg County (Todd's Branch), monazite. Mitchell County has long been a source of rare radioactive minerals. Hatchettolite, gummite, columbite, sam­ arskite, altered samarskite, rogersite, cyrtolite, fergusonite, uraninite, urano­ til, phosphuranylite, autunite, and monaz­ ite, are found in a number of localities. Rutherford County yields similar species. South Carolina has produced minor amounts of uranium minerals. Uraninite and nivenite are found associated· with allanite near Marietta, Greenville County. Anderson County yields some columbite \vith allanite and other rare minerals.

Oregon There are several indications of urani­ ferous formations in Oregon; these com­ prise the highly fluorescent silicas and opals, none of which has commercial value as a source of fissiQnable metal at the present time, though fine speci­ mens are highly prized by collectors. Large masses of uraniferous silica are found at Pueblo mountains, south of the Steens mountain area, near Denio in Harney County; also the material is found scattered over the ground and in submerged masses near the Warm Springs Indian Reservation, in southern Wasco County. In the latter instance, the perlite deposits frequently show more radioactivity than the surrounding rocks. Fluorescent silica is also found near Madras in Jefferson County. Often the material is associated with agate, chalcedony and common opal, and with rhyolite, especially the Mutton Mountain district of Wasco County, near the Warm Springs Reservation. Monazite is frequently found in Ore­ gon, especially in the black sands, where it has been known to occur for many years; this is also true of tantalum, co­ lumbium and other thorium minerals. Zircon is known to be widely distributed in Oregon. The metal zirconium, derived from the sands carrying zircon, has recently come into prominence. The U. S. Bureau of Mines at Albany, Oregon has carried out researches in the recovery and refinement of this metal, for various commercial uses. What future the black sands of the Ore­ gon coast may hold still remains un­ known. At one time these sands were mined for their gold content, but the rich

areas were soon mined out, and these notable deposits have remained untouched for many years. Pennsylvania Uraninite and various secondary urani­ um minerals have been reported from a number of localities in the state. Usually these are encountered in quarying work or in mining. Uraninite, and several al­ teration minerals were reported from Philadelphia County, Fairmount Park. The uraninite is generally extensively altered on the exterior, with often an un­ altered core of uraninite comprising the interior of the mass. . Carnotite has long been known ill con­ glomerate on Mount Pisgah, three-quar­ ters of a mile north of Mauch Chunk, in Carbon County. It occurs in a small area of the rock known as the Potts­ ville Conglomerate, often found as the cementing material holding small pebbles together. The carnotite has been known since 1874, but it has been used only as a source for mineral collectors, and no commercial workings have been under­ taken. Carnotite is also found in the Williams quarry at Easton, just north of the city. Other radioactive minerals are also found in this quarry. Allanite is found in Chester County, at Bethlehem, in East Bradford and Cov­ entry- townships; also, at Princeton in Lawrence County; Lehigh County, at Allentown; Philadelphia Co u n t y at Frankford, nearly all of which localities yield the allanite in granitic rock

South Carolina Monazite is found in deposits of com­ mercial value in Anderson, Cherokee, Greenville, Laurens, Oconee. Pickens, and Spartanburg Counties. It has beel} mined near Gaffney, Cherokee County, and south of Greenville, in Greenville County. Polycrase is found 4 miles from Marietta, in Greenville County. See North Carolina. South Dakota The pegmatites of the Black Hills have produced small amount of pitchblende and various alteration products. usually as small pockets encountered in mining operations. Autunite is found in the peg­ matites of Black Hills, near Keystone, as at Custer and Spokane. Tantalite and columbite are also found in the pegma­ tites. Tantalite 0 c cur s in Pennington County, n ear Keystone. Columbite is found in Custer County, and has been

59

THE URANIUM MINERALS mined near Laughing Water Creek, north of Custer; in Lawrence County, Tinton area, and is abundant in gold placers in the Nigger Hill district, in the Yolo and Centennial claims; in Pennington County, in pegmatites near Hill City, Oreville, and in upwards of a dozen mines near keystone. Uranocircite is also found in this locallty. Uraninite, torbernite and autunite are found in Pennington County, at Bald Mountain.

Texas A number of rare minerals were found in some quantity in the now inaccessible Barringer Hill locality in Llano County; nivenite was described here for the first time. Gadolinite has been reported in small quantities in Burnet County, and is found in the red granite area with the exception of one locality. Fergusonite, gadolinite, yttrialite, allanite, gummite, nivenite and cyrtolite have been reported in a locality five miles south of Blufton. Utah The southeastern Utah carnotite areas are described in more detail in the section for Colorado. This uranium ore has been known for years in Emery County, and mined on the east flank of the San Rafael Swell, 13 miles southwest of Greenriver, in Upper Jurassic(?) sandstone; it occurs in Temple Rock and along ·the South Temple Wash, with uvanite, metahewet­ tite, and other uranium and vanadium minerals. and with asphaltite on the southeast side of the swell and along the San Rafael rvier. Carnotite is found in Garfield County, on the east and south­ west flanks of the Henry Mountains, especially on 'C res c e n t and Trachyte creeks; also in Grand County, near Rich­ ardson, where it is mixed with calciovol­ borthite 'and copper minerals, and 15 to 20 miles southeast of Thompsons with tyuyamunite. Carnotite occurs in many place in the La Sal Mountains, particularly on Pack Creek; also in San Juan County, with many deposits in Dry, Big Indian, and Lisburne valleys north of Monticello. The ore is also found in Washington County, near Washington, Silver Reef; \Vayne County, in the north end of the Henry Mountains. Autunite occurs 9 miles south of Pah­ reah, in Kane County; also in Washing­ ton County; Silver Reef, in sandstone formerly worked for silver. Monazite oc­ curs irt Uinta County, in the black sands of Green River, Jensen district.

Torbernite occurs in Kane County, at the Virgin 'River; also, San Juan County, in the La Sal Mountains. Uranospinite is found 9 miles south of Pahreah in Kane County. In Wayne County, a urani­ um sulfate has been reported as occur­ ring in a fine-grained sandstone with cop­ per carbonates near Fruita. Uraninite is found in small amounts at Ogden Canyon, Weber County. The un­ common uranium mineral zeunerite is found occasionally in the ore of the Cen­ tennial Eureka mine as minute yellowish­ green crystals in barite, Tintic district, in Juab County. Utah yields tyuyamunite a Ion g with carnotite and other vanadium minerals in Emery and Garfield counties; also, Grand County, prominently crystallized at Rich~ ardson, with carnotite, and on Pac k Creek. The mineral tyuyamunite is found in San Juan County, in East Canyon and' Big Indian Creek; also, Uinta County, as small de p 0 sit s in pre-Cambrian(?) quartzite, on Red Creek, Browns Park, with copper minerals. Virginia The pegmatites of Virginia are of in~ terest both because of the variety of rare and interesting minerals which they con~ tain and for the reason that they have served as sources of specimen material hom time to time. The deposits are found in the crystalline belt of Virginia which is situated between the Blue Ridge Moun­ tains on the west and the coastal plain on the east. The Amelia area, located in Amelia County, is of interest in connec­ tion with radioactive minerals.

Washington Monazite is found in the black sands at Moclips and Grays Harbor, G ray s Harbor County; also in the sands of the Columbia river, Douglas County, and at Wilmot bar on the same river, in Stevens County.

Wyoming In general the country rocks of Wyo­ ming show radioactivity to an abnormal degree, indicating they doubtless carry an abnormal amount of uranium and thori­ um. Percolating waters passing through these rocks frequently leach out soluble uranium saits, along with silica, and later deposit the silica as uraniferous agate, chalcedony. and common opal. For this rea son great quantities of fluorescent agate and common opal have been found at many localities in the state. The water

60

POPULAR PROSPECTING

One of the many annual exhibits sponsored by the many amateur gem and mineral clubs throughout the Country. Hundreds of private and commercial exhibits may be seen at these gatherings of the prospectors, gem hunters. mineral collectors, and rockhounds. These exhibits of specimens are of considerable value to the novice, enabling one to gain a good idea as to what type of materials are in demand and their approximate value.

worn pebbles of moss agate, generally known as Sweetwater (locality) agate, are widely known, and fluoresce the characteristic yellow-green of uranium, under short wavelength ultraviolet light. The schroeckingerite deposits, on Lost Creek, in the Red Desert, some 40 miles nor t h of Wamsutter, are perhaps the most extensive deposits of uranium in the state., These deposits were first noted by local residents in 1936, and thought to be sulfur, as the mineral is quite fri­ able and has a color very similar to sulfur. The deposits were first visited by the write in 1936, and identified as uranium. Specimens were studied by Dr. E. S. Larsen of Harvard and described in the February 1936 issue of The Mineralogist. The minerals was first thought to be a new species (dakeite), but later shown to be identical with schroeckingerite. Schroeckingerite of Wyoming occurs in crude clay-like gypsite, over a con­ siderable area. The creek water flowing through the deposits are also slightly uraniferous. The yellow mineral occurs

as small hard grains and nodular masses distributed throughout the gypsite. In some places the deposit has a thickness of 3 feet or more, near or at the surface in many places. The deposit has not been prospected enough to learn its extent, but it appears to extend over a consider­ able area, and is located at a high eleva­ tion on the flat backbone of the Rocky Mountains. The origin of the mineral has not been definitely established, but was no doubt derived from the weathering of some primary (pitchblende) deposit. The mineral is highly fluorescent, a yellow­ ish green. The next most notable deposits of ura­ nium are situated near Lusk. and these have been operated on a commercial basis. Several important secondary ura­ nium minerals are included in the Lusk deposits. Allanite occurs in Wyoming near Al­ bany Station, in Albany County, in peg­ matite. Monazite is found in the black sands of the Bald Mountain district, in Carbon County, and has been reported in Sheridan County, from the Bighorn Mts.

./

CHAPTER SIX

Notes On Prospecting During the past few decades, a number of new instruments have been developed which have proven of considerable value in the location and exploration of various mineral deposits. These instruments are in wide use by professional and scientific exploration companies. Suitable instru­ ments in this class have also been de­ signed and manufactured especially for the prospector. These include tools like the Geiger counter, portable ultraviolet I amp s, scintillometers, magnetometers and similar instruments used in geophys­ ical prospecting and exporation work. In­ cluded in this class are various types of metal locators, widely used in military work in the detection of buried mine fields. One of the pioneer manufacturers of geophysical prospecting equipment, is the Fisher Research Laboratories, 1961 Uni­ versity Avenue, Palo Alto, Calif. This well known finn has kindly supplied us with the following information pertinent to the possibilities, and general utility of this type of modern equipment. \Vhile these instruments arc not highly com­ plicated, yet the instructions for their use should be carefully noted in order to use these tools in an intelligent manner. During the past twenty to thirty years much has appeared in print concerning the invention and development of differ­ ent types of equipment designed to aid in the locations and development of subsur­ face mineral deposits of significant eco­ nomic value. The claims of the com­ panies marketing these items as well as the pseudo scientific writers describing them have created in the public mind many false or at best semi-correct im­ pressions as to just what can be accom­ plished through the use of modern geo­ physical equipment. Some of the more common misconcep­ tions are that instruments exist to locate gold and silver as such and to differ­ entiate it from any enclosing or asso­ ciated ores, that subsurface water can be definitely located by means other than drilling, and that the large petroleum companies have some method of telling in advance whether or not there is oil be­ neath a given piece of property. It is obvious from a study of the patents issued over the past twenty years that the

very great mojority of the progress made has been in those instruments designed to aid in the exploration for structures favor­ able for the accumulation of oil and gas and in the proper development of pe­ troleum deposits once they have been found. The reason for this is directly re­ lated to the tremendous economic return to be realized from the successful location of an oil bearing structure. Hence, tre­ mendous sums have been made available for research and development of any type of geophysical equipment that could in any way facilitate the location or develop­ ment of petroleum deposits. Among the various items of equipment in extensive use at present for petroleum exploration are the reflection seismograph, the mag­ netomer, the gravimeter, and electric and radioactive logging devices. In spite of the fact that there has not been a tremendous amount of funds avail­ able there has still been a steady develop­ ment of geophysical equipment for other applications such as the location of ores and placer channels, the solving of foun­ dation problems for the engineer, and the study of ground water levels and quality. Among these are the different types Elf inductive electromagnetic equipment, the ground and airborne magnetometer, the portable ref r a c ti 0 n seismograph, the Geiger counter, and the ultra-violet or black light. Naturally, some of the methods men­ tioned above have different applications in the various fields of geophysical pros­ pecting. For example, the seismic and magnetometer methods can be used in oil exploration problems as well as in certain types of ore exploration problems. In the following paragraphs, the different com­ monly accepted methods of geophysical exploration will be outlined in their sim­ plest form. Particular attention will be paid to inductive e lee t rom a g net i c methods. One of the oldest methods of successful geophysical exploration still in common use today is that using either land or air­ borne magnetometers. The met hod in­ volves the careful study of the effect of different rocks and ores on the earth's magnetic field. The principle will be un­ derstood when it is recalled that an ordin­ ary pocket compass is often seriously af­

1

.1

.,J

62

POPULAR PROSPECTING

fected by the presence of certain types of mineral deposits. The magnetometer is no more than a ve r y sensitive and carefully calibrated compass type instrument and is effec­ tively employed in locating magnetite rich iron ore deposits. In addition it has been and is commonly used in looking for basement rock structure anomalies that wiII perhaps be indicative of over-lying sedimentary rock structure. Since the conclusion of the sec 0 n d World War, it has been common practice to make large scale magnetometer sur­ veys by means of an airborne magneto­ meter. In this way it is easy to rapidly evaluate very large areas at a compara­ tively low cost. Ordinary ground magnet­ ometer instruments are still in use, but have been restricted to smaller scale problems. The instruments involved in this type of work are necessarily quite expensive. Further. the interpretation of the data obtained is often involved and requires considerable experience. Hence, it is general practice to employ contract parties to perform the work and provide prepared interpretations.

Seismic Methods Seismic methods may be classified into two major subdivisions. refraction and re­ Hection. The reflection method is almost exclusively a p p lie d to oil exploration problems. It involves setting off an arti­ ficial shock, and car e f u I study of the travel times and paths of the shock waves as they are reflected back from different subsurface horions. By so doing, it is possible to measure in detail the attitude of sedimentary strata to depths of 15,000 feet. With the refraction method of seismic exploration, a shock wave is also set off by the explosion of a buried charge. The shock waves generated by this explosion are refracted instead of reflected from subsurface boundaries, and are in turn picked up by sensitive geophones set out at carefully measured distances from the point of origin of the blast. By carefully measuring the time the wave takes in traveling from the point of origin to the position of the geophones, it is possible to compute the velocities of the wave front through the surface overburden and different subsurface strata or bedrock. Through studying these travel times and the resultant velocities, it is possible to compute the depth to the different strata or to bed rock.

Metal detectors find many applications.' These remarkable instruments are widely used by treasure hunters and explorers. They also find use in tracing out cover iron water pipes and the like. OccasionaUy. the treas­ ure hunter may find a can of gold coins, but generally he will dig up a lot of metal cans. horseshoes. and an assortment of metal ob­ jects. The depth at which this battery op­ erated unit will function is several feet, de­ pending upon conditions. but the depth of utility is limited. Manufactured by Fisher Research Laboratory, Palo Alto, .California.

It is also possible to obtain considerable information as to the geological nature of the overburden and bedrock. Applications of this method can be found in searching for petroleum type structures, in tracing the position and extent of buried placer channels, and in measuring the amount of overburden to be removed in stripping operations. Iu the late 1920"s and 30's this technic found extensive use in the location of buried salt domes along the Gulf Coast; however in recent years, it has been al­ most entirely supplanted for this use by the reflection method. As with the mag­ netometer, the seismic method requires a considerable investment in equipment, as well as technical knowledge of operation in interpretation. Hence, it is general practice for most of the large petroleum companies and mining firms to employ contract crews of specialists.

Electrical Methods All methods of geophysical prospecting depending for .their functioning upon elec­ trical properties of the earth may be clas­

NOTES ON PROSPECTING

63

sified under this general heading. The major standard subdivisions are described as methods employing (I) natural earth potentials (2) applied currents (3) indic­ tion currents.

Natural Earth Potentials Due to the oxidation of certain types of near surface sulphide ores, electro-chemi­ cal differences of potential are sometimes generated. Such natural currents, when sufficiently pronounced, may often be de­ tected and accurately traced on the sur­ face of the ground. It has been found from experience that the practical appli­ cation of measuring these natural cur­ rents is restricted almost entirely to the discovery of sulphide ore bodies. Applied Currents Dire€t or alternating current is applied to the soil or bedrock by means of some definite pattern of well grounded elec­ trodes. Surface electrical potentials so ob­ tained are a measure of the earth's ability to carry or conduct the applied current. Inasmuch as different rocks and minerals differ greatly in their ability to carry or conduct electric currents, it is possible to use this fact in geologic prospecting. Under favorable conditions problems relating to the determination of depth of overburden, the location of conductive ore bodies, the water table, dikes, faults, and contacts can be aided in their solution by this method. Here again successful op­ eration requires a large outlay for equip­ ment plus extensive experience in the correct interpretation of the data. The most common method of applied current prospecting is known as the Earth Re­ sistivity Method. Electric Logging as used in the petroleum industry is a form of both the natural potential and applied current methods. Induced Currents This method applies an artificial elec­ tromagnetic field set up by high fre­ quency alternating current either passed conductively through the earth by actual contact or applied inductively to the ground by some type of transmitting loop. The electromagnetic field so induced is referred to as the primary field and it in turn induces secondary electromagnetic fields in any subsurface conductors, such as ore bodies, that may be present. The combined, or resultant electromagnetic field, consisting of the primary plus any fields due to subsurface conductors is studied by means of a directional receiv-

Light weight mineral and metal dete<:tor, widely used for locating buried metallic min­ erai deposits, and any metal objects includ­ ing coins. Ores best suited for location by this field, battery operated instrument, are the conductive metallic sulphides and any native metallic ores. This type of instru­ ment is effective at any reasonable depth, and this In turn is dependent upon the size and nature of the ore body and its covering. Manufactu..ed by Fisher Research Labora­ tory, Palo Alto, California.

ing unit. Electrical methods employing a vertical loop transmitter for inductively energizing the ground are the most wide­ ly used of the electromagnetic methods. Fisher Research Laboratory, Inc., has developed two related types of instru­ ments for this method of prospecting. With one of these two the transmitting and receiving units are designed to func­ tion separately. A large vertical transmit­ ting loop is operated by one member of the party while a second man is required to operate the receiving unit. The instru­ ment is well suited for energizing con­ ductive zones that are vertical or are steeply dipping such as veins, faults, and dykes buried under shalIow overburden. The depth range is entirely governed by the physical conditions existing at each survey, but under f a v 0 r a b I e circum­ stances may reach several hundred feet. The second, and more widely used in­ strument, employs a method in which the transmitting' and receiving units are held in a fixed position in relation to each other by means of a pair of carrying handles. This unit has a depth range of

POPULAR PROSPECTING approximately 25 feet, also depending on the existing physical conditions, and is usually operated as a single unit by one man. For certain types of problems the receiving and transmitting units can be separated and employed in a manner sim­ ilar to that of the large vertical loop field transmitter. However, the depth range is not appreciably increased. The unit is suitable for locating any relatively con­ ductive body within the range of the in­ strument. When operating the large field trans­ mitter the receiver is held in a horizontal position so that a null or minimum is registered on the receiver visual meter and in the receiver earphones. Traverses are then made across the strike at dis­ tances of from 50 to 200 feet from the re­ ceiver. Indications of subsurface conduc­ tive bodies are received in the form of in­ creased dial tone and meter reading. When such an indication is found it will . be necessary to tilt the receiver to again obtain the null position. When the conductive zone or orebody is passed it will be necessary to tilt the receiver in the opposite direction to again obtain the null position. The extension of lines per­ pendicular to the plane of the receiver when so tilted will point toward the con­ ductive body so that it is possible to ob­ tain information as to the depth and at­ titude of the vein or ore body as well as its plan or surface location. When using the smaller, coupled, in­ strument the receiver is carefully balanced to the null position over barren ground. When the instrument is then carried over a conductive body in which a secondary field has been induced, an increase in visual meter indica~ion is observed plus a marked increase in earphone tone. The effectiveness of work with either of the two types of equipment described above will depend on several important considerations: 1. The length, and shape of the ore body. 2. The depth of the ore body. The de­ tectability of a conductive body decreases very rapidly with increasing depth. Interpretation One very important point that has been by-passed so far in this discussion is the extreme importance of a thorough knowl­ edge of the geology of the area and of the physical characteristics 'of the ores and rocks to be encountered before any of the discussed instruments can be effec­ tively applied. It should be noted that in

all of the applications, the aid to the pros­ pector, geologist, or engineer is indirect in that only changes can be detected. One can detect changes in the amount of radioactivity, changes in the conduc­ tivity of the earth, and changes in the ve­ locity with which a shock wave is trans­ mitted. It is in the interpretation of what these changes mean that the value of these modern instruments comes to the fore. To express it in another way the prospecting aids that have been discussed are no more than tools for the use of the prospector just as the pick and shovel are tools. And similarly each can contribut.e to the understanding of the prospector's particular problem. No single instrument in itself can provide the answer. Each particle of information obtained through the use of modern exploration equipment must be added to the sum total of information available before any answer can be given. If all of this is kept in mind then it can be said without fear of contradiction that modern science can provide invaluable aid to the modern prospector. Metal Detectors The Fisher Research Laboratories of Palo Alto, California, also manufacture metal and treasure detectors, which are described here. Like all similar instru­ ments, these have their valuable uses, and their limitations. Where indicated these instruments are in wide use, and will be found invaluable. Consider for a moment the vast wealth accumulated and then lost or buried in the centuries past. Consider the ultimate disposition of the great wealth and loot of the pirates and bandits so numerous dur­ ing the early days of this country. Con­ sider the large quantities of family silver­ ware and savings hidden to protect them and subsequently forgotten. What has happened to this great wealth? For the most part it lies buried in long forgotten sites. It lies at the disposal of some mod­ ern explorer with determination and fore­ sight willing to acquire and use the latest and most scientific instruments in his search. The M-Scope Metal and Mineral De­ tector is this instrument. It enables the ex­ plorer through the use of the most ad­ vanced electronic principles to literally see into the earth, beneath floors, into old ado­ be and brick wails, through shallow fresh water, and through pavements. It enables the explorer to rapidly and thoroughly in­ vestigate large areas, to feel confident

NOTES ON PROSPECTING

65

A view in Last Chance Canyon, of Southern California. Note the tilted sedimentary

formations comprising the backqround hills. This region is a favorite for part time gem

hunters. A detailed description of this region appears in the book California Gem Trails.

that he has uncovered all bullion or treas­ ure as well as any other metal objects of interest and value that may be present. Valuable mineral deposits can be de­ tected through the use of M-Scope equip­ ment. Included in geophysical equipment are instruments for detecting conductive ores present in veins, lodes, pockets, and placer deposits: radioactive ores and ma­ terials such as carnotite and pitchblende: and fluorescent ores such as the highly valuable tungsten ore scheelite. These are but a few of the many varied and valuable applications of M-Scope equipment. The Fisher M-Scope Metal and Mineral Detecting Equipment is scientifically de'signed to pro v ide in practical form a sound and usable metal and mineral de­ tecting instrument. In its simplest terms the equipment mea sur e s or detects, through the use of induced electromag­ netic fields, changes in the relative elec­ trical conductivities of the material over which it is carried. The term conductivity refers to the ability of a material to con­ duct an electric current. Since metal ob­ jects and metallic ores are generally much more conductive than the surrounding soil or rock it is evident that they can be detected as conductivity changes if they lie within the range of the instrument. The theory of operation is founded on carefully established scientific facts. All metal objects can be detected since the instruments do not depend for their functioning on the magnetic properties of the buried materials. Hence, all metals

and conductive minerals including gold, silver, copper, iron, etc., can be found with equal ease. Native gold, silver and copper and the metallic sulphides are the ores most suited for this method of geophys­ ical exploration. For those interested in mining, the more prominent of the me­ tallic sulphides include pyrite, chalcopy rite, pyrrohotite, galena, chalcocite, cin­ nabar and molybdenite. Some of the ox­ ides such as magnetite and maganite are also good conductors. Explorers need no special knowledge or experience in order to successfully oper­ ate metal and mineral detecting equip­ ment. Full and detailed instructions and illustrations are provided. It is only nec­ essary to adjust a few controls in order to operate the equipment. Once the neces­ sary tuning has been done the instrument will retain its sensitive adjustment even when operating over rough terrain: or through heavy brush. Only one man is needed for efficient operation so that the treasure seeking explorer need not divulge his secrets to anyone. All of the instru­ ments are highly portable for greater ease of operation and transportation. Once the area to be explored has been reached the instrument is assembled and • adjusted over ground that is known to be barren of treasure or bullion. The instru­ ment is then carried over the suspected site. When the lost treasure is crossed the instrument's receiver will detect it by means of a loud buzzing in the receiver earphones as well as a clear and sharply

66

POPFLAR PROSPECTING

defined indication on the large visual in­ dicator. The depth to which ALL metal and mineral detecting equipment will function depends upon: The metallic surface area of the deposit. The moisture content of the ground. The length of time the metal object sought has been buried. The type of instrument used. Buried treasure including gold or silver coins, metal chests, family silver, gold or silver bullion, and near surface placer gold concentrations. Lost or burried tools-pliers, hammers, wrenches, keys, weapons. Pavement covered manholes, valves, stubs, etc. Lost or buried metal surveyor pro!Jerty markers. MetaL beams, plumbing, or electrical boxes behind brick or plastered walls. Here are some of the limitations and performances of equipment of this kind. Will detect both magnetic and non­ magnetic minerals. Will not identify individual minerals but will indicate the presence of metallic ore bodies within the depth range of the instrument and approximately outline the surface area of the deposit. Will not locate underground water or oil deposits.. (There is no scientifically ac­ cepted instrument for this purpose.) Will locate, within the depth range of the instrument used, local pockets in an otherwise barren vein, veins and bodies of metallic ores, and rich placer deposits. Will not automatically lead, point or direct to a mineral deposit. (There is no scientifically accepted instrument for this purpose.) Will not locate Uranium ores-you need a M-Scope Geiger Counter for this pur­ pose. Will eliminate much unnecessary and time consuming digging and trenching.

SALTING A MINE Salting a prospect or a mine property is a very old practice, and has been fre­ quently applied to gold properties. How­ ever, one of the most notable swindles in this field is the great Diamond Hoax of the 1870's, when two clever swindlers salted some ground in Wyoming, north­ west of Rawlins. These two lads, had made a visit to' the diamond cutting cen­ tersof Amsterdam, and had bought some $36,000 worth of then nearly worthless diamond bort, and for good measure tossed in some red rubies. This consider­

able amount of diamond was then used to salt the ground. Posing as honest prospectors, they took in a San Francisco banker (Ralston) for some $600,0'00 for the pro per t y. The banker had sent a mining engineer to ex­ amine the ground, and sure enough the engineer reported favorably, and actually returned with a handful of rough dia­ monds and a few rubies. A second, and not so trusty examiner revealed the hoax when he discovered a partly cut diamond on the ground. We offer the following, not for the reader to make use of, but for his self protection. Shotgun Method Salting may take place in the mine itself. The shotgun method is very simple and effective. Gold filings from coins or jewelry, loaded into a IZ-gauge shotgun shell are fired at random at the vein to make good ore out of the poor. Carefully placed shots make even better ore. A slight variation of this scheme is to load dynamite with the filings. Using this dynamite the examiner, who blasts down a fresh face in order to avoid any chance of saiting, unwittingly enriches the ore himself. In dry mines the faces may be painted with gold chloride or silver nitrate solutions to up the values. Cases are on record where "veins" were actually made in fissures in the rocks. In one such case cassiterite, the ore of tin was very cleverly mixed with other min­ erals and tamped into cracks and points of the barren country rock. A soluble sUi: cate was then added, and, when this had solidified, a truly art i f i cia I vein was formed. "Vhen later the hoax was ex­ posed, an experienced Cornish miner who had originally reeommended the property explained that "he was not accustomed to the particular vintage of champagne used on the expedition." Salting Sample A less difficult and less expensive means of salting is to adulterate the samples. When the sample is being taken, the metal may be flicked into it from the ash of a contaminated cigar, or dropped in en­ closed in a ball of prepared clay. Long fingernails may be very useful to the salters. Gold, amalgam, etc., can be nicely hidden under these until the critical mo­ ment when someone is not looking too closely. Rickard tells of Philippine women us­ ing this scheme. These women wore a "Mother Hubbard" kind of dress with a

NOTES ON PROSPECTING

67

Part of the noted Plume or flower agate diggings on the Priday Ranch of Central Ore­ gon. Now known as Fulton Agate Beds. The superb gem agate occurs in veins, seams and pockets at various horizons. The waste overburden material is removed by heavy duty power machinery, including jack hammers, air compressor shown here. The diggings shown here have also yielded large amounts of colorful opal filled thunder eggs. The typical sage and Juni!)er covered hills of this reaion are shown in background. Since its discovery in 1934, the Priday Ranch locality is est!mated to have produced no less than $250,000 'in gem, materials, mostly high grade gem agate.

pocket over the left breast. This pocket was provided with gold dust which was transferred inconspicuously by means of wet fingers to the gravel in the gold pan. The woman worked, each sitting up to her waist in water, with her pan near the pocket so that detection was difficult. Furthermore, the gold was taken from the property being examined which made impossible detection of fraud by means of the microscope. '

A Hypo Shot "Salt" can be added to samples even though they are in sealed sacks by giv­ ing them a '''hypodermic'' injection. Solu­ tions of various metals are shot into the bags with a syringe. Some of these solu­ tions are very difficult to remove after they have dried. Such salting cannot al­ ways be detected by panning. Filings blown into the sacks this way are ef­ fective, but are more easily detected. Where samples are crushed and quar­ tered on the property, there is always a chance that some villian will spill a little "salt" in the machines that are used or in the samples themselves, using the long fingernail act again. He might employ a different technique here though and use a dirty handkerchief instead. '

A misguided man might think himself safe, when at last he has satisfied himself that he has taken and prepared for assay a number of good clean samples; but look out, Mr. Gyp is still on his tail. Even the early alchemists placed precious metals ill their crucible bottoms and covered them with wax or other substance to hide them until the assay was made. Holes in charcoal filled with gold and waxed over served to fool the unwary then. even as today. A more modern version of this artifice. which came to me from a very reliable source is the case of the pow­ dered tin in a furnace oil supply. When the furnace was fired, a stream of tin­ bearing oil blew merrily into the firebox coating everything at hand with the re­ markable element.

Salted Crucibles Fluxes and acids used of the assay can be "salted" too, as can the crucibles. In one instance new crucibles were soaked in gold chloride and silver nitrate and dried. The assayer, failing to run blanks for a check, was greatly fooled; and need­ less to say his reputation was ruined. There are assayers too, who don't mind being fooled a little; in fact who will pur­ posely make out false reports. One suc­

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cessful engineer once told me that "Wher­ ever ore is bought and sold there will be someone doubting the results of the as­ sayer." I was this man's assayer, and he told me to be a hundred percent sure of every assay I made. In some cases, as many as two dozen assays were made to get one result, but results were worth all the effort; for, although there were many controversies between buyer and seller, there was never an argument over the validity of an assay after all dissatis­ fied parties had tried several umpires and lost. Besides making deliberate, false reports, an analyst might be guilty of "innocent" salting. This is the result of carelessness in keeping crushing equipment, reagents, and the laboratory in general clean, or the result of improper preparation of the sam­ ples. Most carelessness will lead to high results, though some procedures, such as careless mix i n g or improper fluxing, might bring about low assays. High Grade Ore High grade can be added to the mill cir­ cuit in the same manner as it is slipped into sample sacks. The crushing plant, ball mill, feed, tables, floation cells, or . reagent feeders are possible points for adding the "salt." Reagent feeders that operate continuously without attention serve very nicely since they are incon­ spicuous. Dressing the Mine Some methods of defrauding prospec­ tive buyers do not call for the addition of foreign material, but rather the removal of undersired portions of the vein. Dress­ ing the mine, as such practice is called, re­ quires that low-grade ore be mined out leaving nice large chunks of rich stuff to stare the sampler in the fact. Fine look­ ing specimens scattered over the dumps add to the attractiveness of the under­ ground picture. Such lures are termed "sucker bait." False Weights Deception by these and many other means can take place; but assuming they don't, there is still a way of tripping the unwary. That is by the use of fraudlent weights. Let us say, for example, that the gold is obtained in exactly the right amount from representative samples, and that the true weight of the gold, repre­ sents, therefore, the true value of the ore. But on determining the amount of gold in the buttons, if the weights have had corners cut away or bottoms filed down, the results will be falsely high. Hollow

weights or aluminum weights substituted for platil1um could be used in this farce. Thus it is seen that the ways of the "salter" are many and clever. In fact, one might ask, is there any protection against such a racket? The answer is yes, but only by eternal vigilance. Samples must be taken carefully, notes and observations being recorded at time of sampling. Several low-grade samples which are known not to have been tamp­ ered with, can be mixed thoroughly and divided into unequal parts, and each part saved separately. It will be impossible for anyone to salt these so that assays will be the same. If, then, the assays are unlike and high, the samples have been salted. Cutting a fresh face of ore before sam­ pling protects samplers against the pos­ sibility of either a salted face or a dressed face. Faces that change their appearance in many places when newly blasted should put· one on his guard. All samples should be quartered be­ fore being sent for assaying, one portion being saved for future reference and an­ other for panning. Every sample should be panned for "salt" such as amalgam, metallic filings, or other foreign material. Fine particles of lead added to the pan helps in checking accuracy of the work; they should be recovered. Another portion of the sample should be washed and both the pulp and washings assayed. Gold chloride, gold cyanide, sil­ ver nitrate, or copper chloride used for salting can be detected in this manner. Uranium Mines In a small way, an effort has been made to salt a uranium property by similar methods, but with little success. Uranium, chemical salts, soluble in water have been used in some instances. However, the cost and difficulty of obtaining any quantity of this material has served to discourage frauds of this nature. Any sub­ stantial amount of uranium salts would have to be obtained through bootleg sources, and at a high cost, if available. Refined uranium salts, dumped into a mine property would effect the Geiger counter and the scintillator in the same manner as the crude uranium ores.

PEGMATITE PROSPECTING Pegmatite dikes are rather widely dis­ tributed throughout the world. California, Oregon and Washington abound in these easy to discern formations. Possibly only a short distance from your home you may locate one or a pumber of pegmatite dikes,

NOTES ON PROSPECTING

69

General present day view of the ghost town of Aurora, Nevada. Most of the standing buildings are stone or brick. The original wooden structures were generally salvaged and carted away, or fire took its toll. This old mining camp once held a population of some 10,000 gold seekers, prospectors, miners, and the many human leeches that follow their for­ tunes. When the diggings in the hills in the background were exhausted, the treasure seekers promptly left for greener fields. (Photo by Guy Ransom).

which are likely to yield a host of speci­ mens, including various gem minerals. For example, the pegmatite dikes of San Diego County, California, are noted for their production of gem quality tourma­ line crystals. The pegmatites of the New England states have for many years pro­ duced a wide range of minerals and gems in superb crystals. Regarding pegmatites. Dana states "In connection with deep-seated, coarse­ grained igneous rocks, especiaIly granite, we frequently find mineral deposits known as pegmatite dikes, or veins. These bodies have the general shape 'and characterists of an igneous dike, or a broad mineral vein, though in certain respects they dif­ fer markedly from either of these. Peg­ matite dikes run through the main mass of igneous rock, or fill fissures in the sur­ face rocks. The dikes are characterized by very coarse crystallization."

Slow CooEng Owing to the fact that pegmatite gran­ ites were originally injected into the sur­ rounding formations at some distance be­ 'low the surface, cooling of the mass took

place very slowly, and this in turn en­ abled enormous single crystals to "grow" or "segregate." Cavities are also charac­ teristic of pegmatite formations, and often these open pockets may prove bonanzas - pocket filled with gem mineral crys­ tals of various kinds. Almost 100 dif­ ferent mineral species have been found in the pegmatites of the New England states. Often the surface outcroppings of the pegmatites can be traced for many miles. Since the pegmatite rock is often more resistant to weathering than the surrounding "country" rock, the former is noted as a hill or ridge, higher than the surrounding terrain.

Many Minerals Minerals found in the pegmatite dikes include a number of gem minerals like beryl, emerald, topaz, quartz, amethyst, tourmaline, kunzite. and a number of rare gem minerals. Often these occur in no­ tably large crystals of great perfection. Beryl crystals (non-gem quality), some 14 feet in length and weighing many tons, have been mined in the pegmatites of the New England states.

POPULAR PROSPECTING

Rare Elements Minerals of the rare elements and rare earths are also common to pegmatite dikes. For example, the famous Barringer Hill, Texas, pegmatite yielded a large number of uranium and thorium minerals, and numerous rare earth minerals, some of which were new to science at the time of discovery. Lithium, tungsten,' tin, tan­ talum, and columbium are also found in pegmatites. Feldspar and mica are also common to pegmatites. Some of the sin­ gle, feldspar crystals mined in the Black Hills pegmatites weighed hundreds of tons. The enormous mica "books" are derived from the pegmatites. In short, the host of minerals found in the pegmatites are invaluable to the industries, arts, and sci­ ences.

LABINE'S DISCOVERY URANIUM Perhaps some may not realize how Gil­ bert Labine made his world shattering discovery of Pitchblende, at Great Bear Lake, in northern Canada, far north of the Arctic Circle. Back in 1900, J. Mackintosh Bell of the Canada Geological Survey, made a detailed study of the salient geological features of that then little known country in the ice-bound north. For some 30 years Be1l's report gathered dust and remained in ob­ scurity as a geological curiosity. In 1930 Gilbert Labine's sharp eye fell upon the old works of Bell. Labine was an itinerant mining stock salesman, but he and his brother were fired by the Bell reports, and by stories of mining as told by their uncle, Jim Labine. The Labine brothers, falling into the spirit of a mining community in which they resided, were soon engaged in pros­ pecting and gained valuable experience in the noted Cobalt and Porcupine dis­ tricts of Canada. Gilbert Labine was soon aware of his technical deficiencies and he enrolled at Haileybury Mining School where he went through a comprehensive course in mineralogy and geology. Armed with this fresh knowledge, Labine struck out for the far north to investigate Bell's old reports of 1900, where green stains of copper and cobalt bloom had been re­ ported. Labine's mineralogical training sug­ gested to him that wherever cobalt oc­ curred silver should be found also. At th time he did not even dream of pitch­ blende. Flying from Edmonton, Labine

surveyed the region around Great Bear Lake, from the air, especially the area around Echo Bay, the scene of Bell's early observations. The survey made a lasting impression on Labine. In March 1928, Labine and a partner went by the water ways as far north as was possible. Then with a crude sled, the two men hauled almost a ton of supplies to Echo Bay, from the headwaters of the Camsell river, a terrifying journey of hardships that required full six weeks. En route his partner, Charles St. Paul be­ came snow blind, but they ,dared not stop en route for fear the Spring thaws would melt the snow and ice and leave them stranded and facing death on the open Barrens. Taking his place in front, Labine har­ nessed his blind partner in position and after days of agony reached the compara­ tive safety of Echo Bay on Great Bear Lake. With his partner disabled, Labine managed to scout around and he soon found what he sought, the cobalt bloom stains, outcrops of heavy masses of native silver, and a heavy black mineral, which in his new academic role, Labine at once recognized as pitchblende. And so the Eldorado Gold Mines, which had failed to develop a gold mine in Mani­ toba, now began to produce fabulous rich ores of uranium, accompanied by equally fabulous quantities of silver. Labine, truly a man of destiny, served early notice on an incredulous world that the atomic age was about to become a reality. Not alone was the uranium discovery of Labine highly important, but his work also led to the discovery of gold at the world famous Yellowknife district farther south on Great Bear Lake. It is safe to say that the discovery made by Labine, rates as the most important or among the most important mineral discoveries ever made. Some may have been under the impres­ sion that Labine, was merely a wandering prospector who by sheer good fortune stumbled upon this discovery. Dispel the thought. Labine was an intelligent man and a student. He first made a detailed study of early geological reports, then he prepared himself with a knowledge of mineralogy and geology,so when he did go into the field he ,was qualified to identify what he saw. Labine had no Geiger Counter, he had no large geophysical crew, and 110 finan­ cial backing to speak of. He made his dis­

NOTES ON PROSPECTING

A gem hunter in the Black Hills of South Dakota. June zeitner of Mission, South Da· kota, searches through the rock of a talus slope, hunting the valuable and elusive Fairburn typ'e of agate. A trained and skilled eye is required to distinguish the gem pieces from the worthless rock.

covery through his own knowledge as a student, and shall we add a good measure of intestinal fortitude. There are some 1,300,000 square miles of bleak and for­ bidding territory in northern Canada, and the casually wandering prospector of ·the old school would stand little opportunity of making a chance discovery, let alone being able to survive in some of this re­ gion. The Great Bear Lake uranium de­ posits have been Nationalized, and are be­ ing operated with more or less secrecy, it is understood that the entire production is goin to the U. S. A.

BY PASSED BONANZAS Patrick Fancher, an old timer in the famous mining camp of Silverton, Colo­ rado, has given us the following ante­ dotes, where prospectors have passed by fabulous fortunes, simply through their lack of knowledge. Mining history is replete with many in­ stances of great fortunes passed up be­ cause the prospector failed to recognize the value of the mineral he had found. In most cases they were minerals which the average mineral collector or student of mineralogy would recognize instantly. The gold rush of 1849 is a good place to start. The gold-crazy Spaniards had been taking their siestas over this vast California treasure for countless decades. ::rhe haughty Conquistadors, however, had

no use for a gold pan, or a pick and shovel. They preferred to take their gold with the sword. That, incidentally has been the approved method through the centuries. That observation is more political than mineral, but I am not "viewing with alarm." The Russians, those astute poli­ ticians, once sold us a tremendous min­ eral deposit for only seven million dollars. Single mines in Alaska have since pro­ duced more than this sum, and the sur­ face has today hardly been scratched. Yet at the time of this purchase there was op- . position in Congress for this "waste" of money. 'When Alaska is made a state, a state large and potentially richer than Texas, it may well give an impetus to Alaska min­ ing which will equal the Klondike rush. Mineralogist would flock there, and would not make the mistakes so commonly made by the old Timers, who looked only for the yellow metal, and usually could rec­ ognize few if allY other minerals - like the rich copper ores of Alaska. Un­ dreamed of bonanzas would be found, and the United States itself would receive a needed pecuniary transfusion. A million Americans with an urge to make a better living will succeed far bo;:tter than the best laid plans of politicians. N ow let me hasten to apolize to the fair state of Texas for having said that any­

'12

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POPULAR PROSPECTING

thing could ever be larger. And the Texas cowboys who drove their longhorns over the Chisholm Trail can be excused for not having recognized the vast mineral wealth beneath them. Prospecting for oil and the like requires more equipment than a pan and a burro. The wagon trains of 1849, enroute to. California, it goes without saying, passed by vast wealth in silver and gold and other minerals in their haste to reach the far West diggings. The human tide rolled up to the Pacific, and then flowed back to the Rockies where decades later vast mineral wealth was found. A few lovable old prospectors had stopped to pan gold in Nevada's Carson river and its creeks. They found enough gold to keep them in bacon and beans, and an occasional bottle, but their efforts to separate the gold from the sand was hampered by the "blue mud." A passing Mexican informed them it was "La Plata," but the prospectors were neither rock­ hounds or linguists. They failed to recog­ nize the Mexican word for silver, so the fabulous Comstock Lode was undisturbed for decades. Comstock himself was a Can a d ian sheepherder. He was one of the thirsty gold panners, and was therefore on hand when the silver lode was found. He staked out claims worth many millions, but he never made a dime. When a good drink­ ing companion hit town, Comstock would ask him if he had a claim. If he had none then Comstock presented hirtl with one. It is small wonder that Comstock was the most popular man in camp and lent his name to the lode. One of his cronies. 01' Virginny, took a dim view of the whole business and was jealous of his friends prominence. So dur­ ing a drinking argument one day he scruf­ fed a mark in the street and announced: "Then I call this spot Virginny." And Virginia City it is today. Some of the boys did make fortunes but they could not hold on to them for long. A lady who kept a boarding house for the panners accepted shares in their claims in payment of board bills. In view of the tremendous fortune this lady made, it would appear that the cost of food in those days exceeded even today's high prices. As the wave flowed back eastward it passed the veins at Goldfield, Tonopah, and numerous others, which were not dis­ covered until early in this century. The

Pikes Peak rush brought many prospec­ tors to Colorado, but for many years they failed to recognize the tremendously rich tellurides at Cripple Creek. Here in the San Juan Mountains the silver miners threw away the rich gold of the Campbird and Tom Boy. When Leadville was in its infancy a character named Chicken Bill salted a shaft and sold it to the fabulous Haw Ta­ bor. Bill boasted about it in the saloons, but his joy was short-lived. Tabor sank the shaft a little deeper and the mine paid off into the millions. He had found an­ other great mine. Another character of that period was driving a tunnel but became discouraged and sold it for a small sum. The new owner hit a bonanza within ten feet. For­ ever after, when he was in his cups, "Ten­ foot" McGinnity would proclaim to all and sundry, ''I'll never quit another tunnel until I've driven just ten feet more." Perhaps we modern rockhounds should not judge the old prospector too harshly. On Bartlett Mountain in Colorado, is the great Climax Molybdenum mine. produc­ ing today some 16,000 tons of ore per day. Opened less than 2S years ago the Climax stock has jumped from ten cents a share to around $60.00. Thousands of miners and prospectors had passed over the Cli­ max properties, but we will overlook that too. For in 1890 the Colorado School of Mines, no less, had identified the mineral as graphite.

LOST MINE FABLES "Lost" and ficticious mines of reputed fabulous wealth have long held a fascina­ tion and lure. In recent years there has been an unusual amount of activity di­ rected toward the hoped for rediscovery of these "lost" mines-if they ever existed as reported. There must be 50 or more of these in various parts of the United States, which have been referred to in print at various times during the past decade. As far as we have been enabled to learn, none of them have been rediscov­ ered, despite the fact that thousands have searched, some having continued search­ ing for many years, expending substantial sums of money, time, and suffering con­ stant disappointment. 'vVe have no objections to anyone searching for "lost" mines, but it does seem like these individuals are bucking a losing game, with slim chances of success, if indeed their objective even exists.

NOTES ON PROSPECTING

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73

Fireplace partly faced with sawed slabs of colorful fluorescent rocks, mounted in plaster paris to form removable and portable plaques. The use of sawed slabs on fireplace fronts and similar ornamentation, offers a neat and easy means of installation. Commercial and private ornamentations of this nature are increasing the demand and value of these materials.

Nearly every human being has within him that lure of discovery. the same lure by which Columbus discovered America, and by the same lure which Magellan sailed the seven seas. Practically all these so-called lost mines we read of have an almost identical his­ tory. The familiar one where a prospector or party, out in the wide open spaces, made a fabulous discovery. Then their water. and food ran out, or perchance In­ dians beset them. In any event they had only time to scoop up some of the rich rock. or a handful of gold nuggets, make a dash to civilization and arrive in a des­

perate and pitiful condition oi suffering. Mayhe the dying prospector made a rough sketch map, and passed it along to his benefactor. In the case of the most noted Oregon lost mine, the Blue Bucket, some youngsters gathered up a quantity of gold nuggets and filled a blue colored bucket, hence the name. The blue bucket was presumably tied to a wagon and thus reached civilization, just a few steps in advance of starvation and blood thirsty Indians. Many of these lost mine fables are of comparatively recent history. but they also date back to the time when the white

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POPUI,AR PROSPECTING

man first trod America, back to the days of Coronado. They include fabulous gold and silver mines and gem deposits, but all have the similar history, once discovered and then "lost." Even the original discov­ erers have never been enabled to return to the proper spot. This would seem most incredible. vVe can well imagine a city lad losing himself in the forest or desert wilderness, but hardly an experienced, mountain or desert man. Still that's the way the tales read. We can not think of any more fascinat­ ing and thrilling rea din g matter than these many published works on "lost" mines. The available descriptions, maps, and other data, are invariably so vague, and permeated with so much hearsay in­ formation. that in most cases it would ap­ pear that the deposit, as described is of questionable existence. Hence the chances of making any discoveries of this nature based on this type of data, are practically nil. Still thousands follow this lure of hope and discovery, which beats in the hearts of every human being. \Vhat we are getting at is that it seems unfortunate for one to waste his time in a search for a ficticious objective. During the past few years we have had numerous inquiries pertaining to information on lost mines and the like. There are still many opportunities for discovery in fields where the chances are far better than in the lost mines field. \Ve may cite. for example, the uranium pros­ pectors, where rich and profitable dis­ coveries have been made in both the United States and Canada during the past decade. Uncle Sam spends millions of dol­ lars, conducting surveys, gathering infor­ mation to pass along to the serious urani­ um prospector. This is not vague or hear­ say information, and many have profited by acting on this data. The possibilities of discovery in the field of gold mines, lode or placer, have be­ come increasingly less with the passing decades. Hence the once familiar gold pt'ospector with his burro, has passed in­ to history. and is now replaced by the jeep rid i n g prospector carrying a Geiger counter, or similar electronic equipment. The development of science and indus­ try during the past few decades has brought forth a tremendous demand for many new metals, including uranium, ti­ tanium, zirconium, tantalum, tungsten, nickle, lithium, a whole series of the rare earth elements, to name just a few,

amongst the metallic elements. Tremend­ ous demand for aluminum, and magne­ sium have brought about wide activity. Not so long ago most of these met'als were merely laboratory curiosities, and of little commercial worth. The single de­ velopment of the jet engine, for example, has brought forth a number of revolution­ ary metalurgical miracles. Even a huge deposit of common obsidian may be of considerable value, if of suitable quality as a building material aggregate. In the field of gems, there are still many opportunities for valuable discov­ eries, perhaps none of fabulous worth, but still worth hunting. In descriptive lure, this field of discovery has never been ex­ ploited in the ~ame manner as the lost mines. Often when we have an inquiry for lost mine data, we suggest a book giv­ ing authentic data for gem discoveries, but these lads are simply not interested. This is quite understandable. For those who will follow the lure of "lost" mines, we offer here The Great Diamond Hoax of the 1870"s. This is quite authentic, and a matter of historical rec­ ord, and not based upon' any vague hear­ say. As a matter of fact the Bank of Cali­ fornia, at San Francisco closed its doors through this swindle, after Banker Rais­ ton had handed out some $600,000 in cash, Here is the story. Diamond bort at the time it was bought in Amsterdam was worth only about twenty-five cents per carat. it is now worth around $4.00 per carat, and some $35,000 worth was used to "salt" the ground. A good deal still re­ mains to be screened out provided the exact place of salting is found. GREAT DIAMOND HOAX This swindle rates as one of the most fantastic pieces of chicanery and fraud ever per pet rat e d, and incidentally it gained the perpetrators a neat sum of money. The best printed description of this hoax was written by Asbury Har­ pending (1913), his book The Great Dia­ mond Hoax, printed in San Francisco. Unfortunately this fascinating classic has been long since out of print. and is an item hard to obtain. A brief outline of the swindle, as given by Harpending, may be of interest. Along about 1872, two innocent appear­ ing "prospectors" approached a prominent San Francisco banker with the fantastic story of the discovery of a great diamond field. Naturally, as bankers go, the in­ tended victim was very skeptic, but the

NOTES ON PROSPECTING

75

Gem Hunters on a Sunday often throng the Oregon Pacific Ocean gem beaches. These sands, in places are loaded with zircon, iIImenite, monazite, garnet, mangetite, and other valuable minerals. In an earlier day these "black sands" were worked for their gold and platinum content, but these isolated rich 'patches were soon worked out. For many years efforts were made to ut!lize these sand minerals with little success. With the ever increas­ ing demands for the newer metals, it is likely these sands will eventually come into com. mercial prominence.

con men had a sack of diamonds (rubies, etc., thrown in) to bolster their claims. After considerable negotiations, during which time the diamonds were examined by various experts, preparations were made to send "experts" to the field to verify the claims made. These men re­ ported back to the banker that the claims were not false, and they even brought back diamonds to offer as proof. Finallv after more conferences. the banker -and his associates handed over to the swindlers some $660,000. Shortly afterwards. others were sent to examine the claims, and a keen mining engineer . finally found a diamond that plainly showed marks of lapidary treatment. The whole hoax then blew up, but in the meanwhile the slick promoters had de­ parted for parts unknown. It came out later that these two men had gone to one of the diamond cutting centers of Europe and had bought up 'I. quantity of greatly inferior rough dia­ monds, rubies, etc., to the tune of about $35,000, to be used to salt the ground. L nfortunately, for the swindlers, there was among this lot a single stone that had been on the diamond lap, and tossed aside as a reject, and not finished. The diamonds and other rough gems were scattered upon the ground, and cov­

ered slightly, over a considerable area. Hence by careful search it was possible to pick up a stone here and there. Simple enough, but effective in this case. Count­ ing the cost of the salting, and allowing for expense money, the two sharpers made about $600',000 net profit to divide, which they did. As near as the writer can gather from various sources, the locality of the salting is in the Red Desert country, some miles north and east of Wamsutter, Wyoming. Anyone who is familiar with this region, situated on the barren backbone of the Rocky Mountains. will appreciate that this would be an ideal place for a hoax of this kind. In 1872, it was absolutely unsettled country, just as it stands today. In the past it was only visited by sheepherders with bands of sheep during a few months of the summer, and so it is today, except that now jade hunters and uranium hunt­ ers swarm over the country during July and August-the only safe time to go in there, as the elevation is around 7,000 feet and the stranger may be trapped by a sudden blizzard in any other month of the year. The most reliable information seems to be that the two swindlers, accompanied by the banker's representative, went by

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popeLA R PROSPECTING

rail to Rawlins (then called Rawlins Springs), Wyoming, on the Union Pacific Railroad. At that time there was no rail­ way station at \Vamsutter, situated some miles west of Raw lin s. At Rawlins Springs, the party engaged a team of horses and a buggy. and hit out across the open country. just as we may do today by auto. According to the length of time they are said to have traveled, and the direc­ tion of travel, this would place them any­ where (details always vague) from 20 to 45 miles northwest of Rawlins Springs, and this in turn would have landed them somewhere in the Red Desert, north, and perhaps east of Wamsutter. Nowhere does there appear any specific reference to the exact spot of the salting, one can only infer from various older writings, and familiarity with the country, after reading. the several printed descriptions. It so happens that jade has also been found in this same region along with de· posits of uranium. The uramum deposits are situated 45 due 110rth of Wamsutter. They were first described in the February 1937 issue of The Min­ eralogist Magazine, by Larsen of Harvard University. At time the uranium was thought to be a new spedes, and was named "dakeite," but it is prob­ ably the previously described species known as schroeckingerite. Over 5,000 acres of ground haye been filed on, and early reports claimed the uranium mineral was noted over most of the area. The present writer is inclined to agree with this claim of extent. based on personal observation made some years ago. However, information is lacking as to the commercial possibilities of the de­ posit. So those who may wish to prospect in this great area of the Red Desert. should keep in mind the diamonds and rubies in addition to the jade and uranium possibili­ ties. The manner in which the ground was originally salted, it would seem rea­ sonable to assume that rough diamonds and rubies still remain to be found.

GEIGER COUNTER CHECK It is advisable to check the workings of the Geiger counter from time to time This may be done in different ways, us­ ing any radioactive sample of a mineral or other substance. Any small and rich specimen of uranium, like pitchblend2 will cause Geiger counters to work like mad. Lacking uranium samples, luminous dials

on any wrist watch or alarm clock will prove fully effective as the mineral sam­ ple, despite the fa c t that the actual amount of radium present in the luminous paint is sub-microscopic in size. The several dry cell batteries in any counter will eventually need replacement, and this had best be done by sending the instrument to the factory, where old bat­ teries will be replaced, and the instru­ ment checked to make sure everything is in good order. The instrument takes very little energy from the batteries. about the same as the pocket size flashlight. Even if the counter is used very little, the dry batteries will eventually, after about 18 months, become exhausted through "old age," and will require replacement. The manufacturers of Geiger counters will replace the special batteries at a low cost, and with little profit to themselves, in addition to checking the instrument. If someone not familiar with the instrument is permitted to t:\mper with it, the factory can not be held responsible if something goes wrong. \Vith ordinary care and usage the Gei­ ger counter will last a lifetime, aside from the batteries. Rough handling and sub­ merging in water will soon ruin it, or cause extensive damage.

URANIUM WANTED In view of the wide interest in uranium minerals, and the extensive use of Geiger counters, there is an unusual demand for specimens of pitchblende, as well as all other uranium minerals. Daily we receive numerous inquiries from readers of The Mineralogist Magazine, relative to the availability of rich uranium ores. Speci­ mens desired for comparative purposes, and for use in testing Geiger counters,. electroscopes, and similar instruments. All rich uranium minerals, like pitch­ blende. now bring premium prices. con­ siderable more than in the pre-atomic bomb days, and still the supply is no­ w her e e qua I to the demand. Supply houses stock of the richer uranium min­ erals appears to be practically nil, or specimens are not being offered, if in stock. For testing and comparative pur­ poses, the richer specimens need not be over 1 x 1 or 2 x 2 inches in size. If any supply firm or individual has a stock of the richer pitchblende (or other species) ores, could readily dispose of them. and at premium prices consider­ ably higher than several years ago.

NOTES ON PROSPECTING

77

Gem hunter at work at the foot of Pony Butte, on the celebrated Priday Ranch in Central Oregon. The shallow, open pit digging, covering only a few acres, shown in the fore­ ground, produced at least $35,000,000 worth of high grade, colorful moss agate. This portion of the diggings became exhausted after several years effort on the part of hundred, of diggers from all over the United States. Additional richer grounds were discovred at a higher elevation on the same property, and these are now in active exploitation.

HOLE IN THE GROUND Generally speaking, a "mine" is a hole in the ground, but it is needless to say that every hole in the ground is not a mine. "Prospects" are potentialities; there is no rule for appraising them, other than experience and the application of good judgment, followed by development, if warranted. However, it must be borne in mind that every mine, even the best was once a humble prospect; they are like in­ fants, with brief pasts and unknown fu­ tures; babies and prospects have much in common; a single blast may blowout all the ore in one, just as the whooping cough may end the uncertain existence of the other. On the other hand, a period of development may bring forth a highly profitable mine, just as a healthy baby matures into a strong and robust adult.

DISTINGUISHING MARCASITE FROM PYRITE Pyrite and marcasite are generally dis­ tinguished by their differences in color, crystallization, density, and ease of oxi­ dation. But when the material is seen in a granular massive or concretionary nodu­ lar form, the color guide will prove for the collector the best means of determin­ ing these minerals. The color of pyrite is generally said to be pale brass yellow, while marcasite is

described as tin white, grayish white, brass yellow, bronze yellow, and other colors. Dana gives the color of marcasite as being pale bronze yellow. Both mar­ casite and pyrite assume varying hues of color under various degrees of oxidation and doubtless some of these discrepancies can be accounted for by oxidation. To make an accurate diffentiation be­ tween pyrite and marcasite the material should be examined under good white light, as a yellow artificial light may tend to impart a yellowish tinge of color. A freshly fractured surface or a surface well cleaned with hydrochloric should be used and compared with a know standard. Under these conditions marcasite will clearly appear tin white to grayish white, without any trace of yellow, while pyrite will show at least a faint yellow. A rough surface will not show the colors plainly and mixtures of the two minerals may also lend difficulty.

SCHEELITE PROSPECTING Another highly successful method of prospecting for scheelite (tungsten), is by the examination of dril1 core samples un­ der ultraviolet light. Recently one of the most important tungsten discoveries yet made in Idaho was by this means. An antimony deposit ne<:or Stibnite, Idaho was being prospected by drilling. Examination of the drill cores, taken from depth re­

78

POPULAR PROSPECTING

vealed the unexpected presence of scheel­ ite. Moreover, according to the amount of tungsten revealed by the ultraviolet light the Idaho deposit holds promise of becoming important. The tungsten mineral, scheelite, fluo­ resces only under radiations given from quartz tube of ultraviolet units which give off wave length radia­ tions. The characteristic blue color of scheelite is best revealed if the ultraviolet light unit is fitted with filter number 986. Examination of drill core or other sam­ ples under ultraviolet light is quick, easy, and can be done at practically no cost. The qualitative detection of scheelite by chemical means is obviously at a disad­ vantage. As a matter of routine, all drill cores and similar samples should be ex­ amined in the laboratory under various ultraviolet units, for the possible presence of suspected or unsuspected minerals in addition to tungsten A t ten t ion is called to the fact that scheelite is sometimes stated to fluoresce yellowish. Hundreds of samples of scheel­ ite tested by the writer revealed only the chaj"acteristic blue color. However, the tungsten minerals powellite and cupro­ scheelite fluoresce 3. strong and charac­ teristic yellowish color. Molybdenum or copper may replace part of the calcium in scbeelite to form powellite or cupro­ scheelite. Scheelite may in some cases be coated by either of these tungsten min­ erals. Hence in testing drill cores, hand s~mples, outcroppings, or placer sands, for the possible presence of tungsten, due attention sbould be given to yellowish as well as blue fluorescing material.

THE SUNSHINE MINE The story of the Sunshine Mine in the Couer d' Alene mining district of N orth­ ern Idaho, reads like a chapter out of Arabian Nights. This noted· silver prop­ erty has returned to the original stock" holders many thousands of dollars for each dollar invested at the outset. The Sunshine Mine was originally staked in 1884 by two prospectors-Dennis and True Blake. The Blake brothers had no idea they were standing upon a fabulous wealth in silver-one of the biggest and richest ever known in the United States. Nature had hidden the silver down in the earth and covered it with a huge layer of rock and dirt. For many years the brothers scratched around upon the surface digging shallow holes whever a thin finger of ore had found its way to the surface. The little are they did recover was rich in silver, but locked up in so much waste rock. The ore won by hard labor was h2.nd sorted and when enough had accumulated it was carried out by Fack burro for shipment to the smelter. Sometimes they labored for a year or more to accumulate enough for a shipment. Finally, after years of hard labor, the brothers had accumulated a tidy sum, and then decided to lease the property to those who had funds for exploration and development. The leasing company, at the outset, had difficulty in financing the ,'lork and it was decided to sell stock in the venture. The property had been ex­ amined by numerous mining engineers, and was always turned down as being too

NOTES ON PR()SPECTING 19 --------------------------------------------------------

80

POPPLAR PROSPECTING

small and uncertain for serious invest­ ment. The promoters selected Yakima, INash­ ington, as a likely place to dispose of stock to the numerous prosperous fruit growers residing in that region. Stock in the Sunshine was purchased by many residents of this region, for what proved later to be only a very small fraction of its real value. Shares in the venture once sold for less than one dollar, and has re­ turned to the stockholders many millions of dollars since 1927. The workings have produced well over 100,000,000 ounces oi silver, most of it won from depth. A sin­ gle dollar invested in Sunshine, in the early 1920's when the stock was low, would today be worth many thousands, paid out in cash dividends and stock splits. At depth, considerable lead and an ti­ mony was encountered in the silver ores, and the Sunshine has produced some 20,­ 0'00,000 pounds of valuable antimony.

AGATES WITH PERLITE Collectors of the colorful agate-filled nodules ("thunder eggs") of the Central Oregon region have long noted that these agate masses are invariably asso­ ciated with a dark colored volcanic glass resembling obsidian and termed such. Dr. Austin Rogers, of Stanford' Uni­ versity has examined specimens of this

volcanic glass and suggests that the term "perlite" would be more appropriate for this material. Perlite is defined as a vol­ canic glass with concentric, shelly tex­ ture and ust:ally with a notable percent­ age of water in chemical combinat:on. Just what bearing, if any this perlite may have in the genesis of the agate­ filled nodules has not been worked out. but seemingly there must be some defi­ nite relationship. At practically every lo­ cality where agate-filled nodules are found in the rhyolite of Central Oregon, a seam or flow of perlite will be noted. The nod­ ules have, so far as can be learned, not been found within the perlite, but the presence of this volcanic glass is gener­ ally noted either immediately above or be­ low the nodule bearing horizon in the rhyolite. The various volcanic glasses (in­ cluding perlite) of Central Oregon, are generally high in silica content and would correspond chemically to rhyolite. In short, obsidian. perlite, pumice aad rhyo­ lite are essentially the same chemically but differ in texture. Experienced collectors of agate-filled nodules in Central Oregon have learned to note and investigate outcroppings of volcanic glass (perlite), for possible as­ sociation of agate. Often tracing float pieces of perlite up a hillside has re­ vealed a deposit of agate filled nodules.