Roger 2

Mineral Appearances: Aragonite - CaCO3 (Calcium Carbonate) Aragonite occurs as small, acicular (needle-like), radiating crystals within the vugs of the basalt. These elongated prismatic crystals are semi-hard (3.5 - 4.0) and very fragile with a vitreous luster, a white streak, and a brownish-yellow to white color. Calcite - CaCO3 (Calcium Carbonate) Calcite occurs as small, compact, yellowish-white, marble-like masses filling the vugs in the basalt. It has a hardness of 3.0 with a vitreous to pearly luster and a white streak. These properties along with brisk effervescence in cold hydrochloric acid make calcite relatively easy to identify. Goethite - [[alpha]]-FeOOH (Iron Hydroxide) Goethite is present in the form of botryoidal brownish-black aggregates. It can be distinguished from siderite by its higher degree of hardness (5.0 5.5) dark brown to black color, and brownish-yellow streak. Goethite also occurs as a thin, brown, poorly crystalline coating over the botryoidal siderite. X-ray diffraction analysis verified the identification. Hematite - Fe2O3 (Iron Oxide) Hematite occurs as compact, granular masses. It is relatively hard (5.5 6.5), has a high specific gravity, exhibits no cleavage, has an earthy luster, produces a red-brown streak, and is a deep red color. Limonite - FeO*OH*nH2O (Hydrated Iron Oxide) Limonite is present in the form of earthy, porous masses and as a crustal material covering the basalt. The physical properties of limonite are highly variable owing to varying chemical composition and habit, but at this location it is yellowish-brown in color with a earthy luster, pale brown to yellow streak, and is very fragile.

Opal - SiO2*nH2O (Hydrous Silicon Oxide) The white or clear opal is present as botryoidal, globular masses encrusting the basalt, as well as being present within the vugs in the basalt. The differences in color of the opal samples may be due to varying impurities in the specimens. Opal is relatively easy to identify. It has a hardness of 5.5 - 6.5, low specific gravity, and a vitreous or greasy luster. It is also fragile, with very small conchoidal fractures present in nearly all of the samples. Siderite - FeCO3 (Iron Carbonate) Siderite is present as botryoidal globular masses within the vugs in the basalt. It has a hardness of 3.5 - 4.0 with a bright vitreous luster and a white streak. The color varies from a very pale brown to a pale yellow or white. The spheres are thinly coated with brown goethite and range in size from 1 to 5 mm. Identification of this mineral was verified by the use of X-ray diffraction in the laboratory. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 (Hydrous Potassium Aluminum Silicate) Biotite occurs as foliated, platy aggregates in the metamorphic rocks. The crystals range in size from <1 mm to 3 mm across and are the main constituent of the mica schist. Biotite can be identified by its perfect basal cleavage, vitreous luster, flexible sheets, and brownish- black color. Garnet (Almandine) - Fe3Al2(SiO4)3 (Iron Aluminum Silicate) The garnets along this route are contained in the mica schist. They are relatively small, ranging in size from <1 mm to 3 mm in diameter. Some of these garnets display a prominent dodecahedral shape but most are in the form of rounded grains. Garnets are hard (6.5 - 7.5) and lack cleavage. Uneven or subconchoidal fractures are common along with an adamantine luster, a white streak, and a dark red-brown color. Identification of this mineral was verified by using the X-ray diffractometer in the laboratory.

Kyanite - Al2SiO5 (Aluminum Silicate) Kyanite is present in the form of elongated tabular crystals ranging in size from 0.5 to 2 cm long and approximately 0.5 cm wide. This mineral is unique in that its hardness varies from 6.0 - 7.0 parallel to the cleavage planes to 4.0 - 5.0 across the cleavage planes. Kyanite has a vitreous to pearly luster, a white streak, and is commonly light blue or blue-gray in color. Positive identification was made by using the X-ray diffractometer in the laboratory. Muscovite - KAl2(AlSi3O10)(OH)2 (Hydrous Potassium Aluminum Silicate) Muscovite mica occurs as small (~ 5 mm), thin disseminated plates in the mica schist. These flexible, elastic plates exhibit perfect basal cleavage, prominent vitreous luster, and a silvery or yellowish-white color. Quartz - SiO2 (Silicon Oxide) Quartz is present as massive, compact, cryptocrystalline rocks in the tailings piles. It is present as a result of hydrothermal activity in the area. The quartz that has been exposed and weathered is coated with a yellow or red-brown iron stain, whereas freshly broken samples are of the smokyquartz or milky-quartz variety. It is hard (7.0), shows no cleavage, but conchoidal fractures are evident, and has a vitreous luster. Sillimanite - Al2SiO5 (Aluminum Silicate) Sillimanite occurs as long, slender, fibrous crystals within the mica schist and in the loose material in the tailings piles. The crystals are 0.5 to 1.5 cm long and approximately 0.5 cm wide. They vary slightly in color from a yellowish-white to gray in the mica schist. The yellowish-white sillimanite present in veins has been weathered and is very fragile, but the crystals within the schist have a hardness of 6 - 7 with a vitreous or pearly luster and perfect cleavage parallel the the direction of elongation. Identification of this mineral was verified through the use of the X-ray diffractometer in the laboratory. Actinolite - Ca2(Mg,Fe)5Si8O22(OH)2

(Hydrous Calcium Magnesium Iron Silicate) Actinolite occurs as elongated prismatic crystals in the metamorphic rocks. The color ranges from a light to dark green, and the crystals exhibit perfect cleavage parallel to the elongation direction. Actinolite is hard (5.0 - 6.0), with a vitreous to silky luster. Actinolite also occurs in a fibrous form with the same physical properties. Positive identification was attained by the use of the X-ray diffractometer, and the Scanning Electron Microscope in the laboratory. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 (Hydrous Potassium Aluminum Silicate) Biotite occurs as foliated, platy aggregates in the metamorphic rocks. The crystals range in size from <1 mm to 3 mm across and are the main constituent of the mica schist. Biotite can be identified by its perfect basal cleavage, vitreous luster, flexible sheets, and brownish- black color. Diopside - CaMgSi2O6 (Calcium Magnesium Silicate) Diopside occurs as slightly elongated prismatic crystals, fibrous radiating aggregates, and granular masses in the metamorphic rocks. Diopside has a hardness of between 5.0 and 6.0 with two directions of cleavage at approximately 90deg.. The crystals display a vitreous luster, a white streak, and are dark green in color. Positive identification was attained by the use of the X-ray diffractometer in the laboratory. Garnet (Almandine) - Fe3Al2(SiO4)3 (Iron Aluminum Silicate) The garnets along this route are contained in the mica schist. They are relatively small, ranging in size from <1 mm to 3 mm in diameter. Some of these garnets display a prominent dodecahedral shape but most are in the form of rounded grains. Garnets are hard (6.5 -7.5) and lack cleavage. Uneven or subconchoidal fractures are common along with an adamantine luster, a white streak, and a dark red-brown color. Identification of this mineral was verified by using the X-ray diffractometer in the laboratory. Muscovite - KAl2(AlSi3O10)(OH)2

(Hydrous Potassium Aluminum Silicate) Muscovite mica occurs as small (~ 5 mm), thin disseminated plates in the mica schist. These flexible, elastic plates exhibit perfect basal cleavage, prominent vitreous luster, and a silvery or yellowish-white color. Scapolite - (Na,Ca,K)4Al3(Al,Si)3Si16O24(Cl,SO4,CO3) (Complex Silicate) Scapolite ocurrs as microgranular masses or aggregates in and on the metamorphic rocks at this site. Some very small prismatic crystals can be seen with the aid of a hand lens. Scapolite has a hardness of 5.0 - 6.5, very poor cleavage, a dull vitreous luster, and is grayish-white in color. Positive identification was attained by the use of the X-ray diffractometer in the laboratory. Azurite - Cu3(CO3)2(OH)2 (Hydrous Copper Carbonate) Azurite occurs as very small, striated, tabular, prismatic, radiating, intergrown crystals in the rocks found in the hydrothermal veins, and as a granular film coating the copper-bearing metamorphic rocks. This secondary copper mineral is semi-hard (3.5 - 4.0), displays good cleavage with a vitreous luster, and has a pale blue streak. It is commonly associated with malachite. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 (Hydrous Potassium Aluminum Silicate) Biotite occurs as foliated, platy aggregates in the metamorphic rocks. The crystals range in size from <1 mm to 3 mm across and are found in the rocks in the hydrothermal veins. Biotite can be identified by its perfect basal cleavage, vitreous luster, flexible sheets, and brownish- black color. Bornite - Cu5FeS4 (Copper Iron Sulfide) Bornite can be found as octahedral crystals at this location, but it is more likely to be found as compact granular masses. It commonly displays a reddish-bronze color which is tarnished to an iridescent purple and blue film. The old miners referred to bornite as "Peacock Ore." Bornite has a

hardness of 3.0, a high specific gravity, a gray-black streak, and a metallic luster. Calcite - CaCO3 (Calcium Carbonate) Calcite occurs as small, compact, yellowish-white, marble-like masses filling the fractures and coating the exterior of the metamorphic rocks. It has a hardness of 3.0 and a vitreous to pearly luster and a white streak. These properties, along with brisk effervescence in cold hydrochloric acid, make calcite relatively easy to identify. Chalcopyrite - CuFeS2 (Copper Iron Sulfide) Chalcopyrite occurs as compact granular masses as a result of hydrothermal activity and metamorphism. It has a hardness of 3.5 - 4.0, a high specific gravity, lacks cleavage, a greenish-black streak, and a semimetallic luster. Chalcopyrite is dark, brassy yellow in color and is coated with an iridescent film. Native Copper - Cu (Native Element) Small amounts of copper are present as compact, filiform masses. It displays the characteristic copper-red color on fresh surfaces. However, most samples are coated with a greenish malachite film or a blackish or iridescent film. Copper is soft (2.5 - 3.0), very heavy, and malleable with a metallic luster. Garnet - (Ca,Fe)3Al2(SiO4)3 (Calcium, Iron Aluminum Silicate) The garnets at this location occur as grossular-andradite garnets. They are present in the rocks found in the hydrothermal veins and at the contact with the surrounding metamorphic rocks. The dodecahedral crystals are small (~ 1 mm across), very hard (6.5 - 7.5), have subconchoidal fractures, and a vitreous luster. Owing to the varying amounts of calcium and iron in the chemical composition, these garnets range in color from light green to pink to red, cinnamon or brownish-black. Positive identification was obtained by using the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Labradorite (plagioclase) - (Ca,Na)AlSi3O8

(Calcium, Sodium Aluminum Silicate) The plagioclase feldspar present at this location is a solid solution between anorthite and albite end-members and contain equal amounts of calcium and sodium. The elongated, white to yellow-white crystals are small (~2 mm long and 0.5 mm across), and display a slight play on colors giving off an iridescent blue color. Plagioclase has a hardness of 6.0, a vitreous to pearly luster, nearly perfect 90deg. cleavage, and striations on some crystal faces. Positive identification was made by using the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Limonite - FeO*OH*nH2O (Hydrated Iron Oxide) Limonite is present in the form of earthy, porous masses and as a crustal material covering the metamorphic rocks. The physical properties of limonite are highly variable owing to varying chemical composition and habit; but at this location, it is yellowish-brown in color with a earthy luster, pale brown to yellow streak, and very fragile. Malachite - Cu2(CO3)(OH)2 (Hydrous Copper Carbonate) Malachite commonly occurs as a green film on the copper-containing metamorphic rocks. It is found mostly in granular masses, but some radiating crystal aggregates are present. Malachite is semi-hard (3.5 4.0), displays good cleavage, has a vitreous to silky luster, a light green streak, and is varying hues of green in color. It is commonly associated with azurite. Pyrite - FeS2 (Iron Sulfide) Pyrite occurs as very small striated cubes and compact granular aggregates. It can be distinguished from chalcopyrite by its higher hardness (6.0 - 6.5), black streak, and bright metallic luster. Pyrite is also a darker yellow color than chalcopyrite. Quartz - SiO2 (Silicon Oxide) Quartz is present as microcrystalline masses in the fractures and contacts, as a result of hydrothermal activity. It is also abundant throughout the tailings piles. The quartz that has been exposed and weathered is coated

with a yellow or red-brown iron stain, whereas freshly broken samples are of the smoky-quartz or milky-quartz variety. It is hard (7.0), shows no cleavage, but conchoidal fractures are evident, and has a vitreous luster. Apatite - Ca5(PO4)3(F,Cl, OH) (Calcium Phosphate) Apatite ocurrs as hexagonal prismatic crystals in alkaline feldspar granite. The crystals are stubby, and commonly terminated by pyramidal faces, and range in size from 1 mm to 3 mm long. Apatite has a hardness of 5.0, with a vitreous luster, a white streak, and is greenish-white in color. X-ray diffraction in the laboratory provided positive identification of this mineral. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 (Hydrous Potassium Aluminum Silicate) Biotite occurs as foliated, platy aggregates in the metamorphosed diorite and gneiss, and as disseminated plates in the granite. The crystals range in size from <1 mm to 3 mm across. Biotite can be identified by its perfect basal cleavage, vitreous luster, flexible sheets, and brownish-black color. Corundum - Al2O3 (Aluminum Oxide) The corundum occurs as small hexagonal crystals ranging in size from 1 mm to 5 mm. They are most abundant in the bed of the intermittent creek. However, it may be neccessary to dig down two or three feet and sieve the gravel to find them. Corundum is very hard (9.0) with an adamantine or dull vitreous luster and is gray-black to grayish-white in color. Garnet (almandine/pyrope) - (Fe,Mg)3Al2(SiO4)3 (Iron Magnesium Aluminum Silicate) Almandine/pyrope garnets are found at this location. The samples are in the garnet-biotite gneiss and display distinct dodecahedral crystal form, have a hardness of 6.5 - 7.5, and are bright red in color. The crystals are relatively small, ranging in size from 1 - 3 mm. Positive identification was obtained by use of X-ray diffraction in the laboratory. Microcline - KAlSi3O8 (Potassium Aluminum Silicate)

Microcline occurs as small prismatic crystals, ranging in size from 0.5 mm to 5 mm, and as granular aggregates in the syenite. Microcline is hard (6.0 - 6.5), has nearly right angle cleavage, a vitreous luster, a white streak, and is pinkish-white in color. Identification was verified by the use of the X-ray diffractometer in the laboratory. Muscovite - KAl2(AlSi3O10)(OH)2 (Hydrous Potassium Aluminum Silicate) Muscovite mica occurs as small (~ 5 mm) thin disseminated plates in the diorite. These flexible, elastic plates exhibit perfect basal cleavage, prominent vitreous luster, and a silvery or yellowish-white color. Phlogopite - K(Mg,Fe)3(AlSi3)O10(F,OH)2 (Hydrous Potassium Aluminum Silicate) Phlogopite mica occurs as very small (~ 1 mm) six-sided plates in the metamorphosed syenite. It displays perfect basal cleavage with vitreous or pearly luster, and is yellowish-brown in color. Pyrite - FeS2 (Iron Sulfide) Pyrite occurs as very small striated cubes, ranging in size from 0.1 mm to 0.2 mm and as compact granular aggregates in the syenite. It can be distinguished from chalcopyrite by its higher hardness (6.0 - 6.5), black streak, and bright metallic luster. Pyrite is also a darker yellow than chalcopyrite. Zircon - ZrSi04 (Zirconium Silicate) Zircon crystals ranging in size from 0.5 mm to 4.0 mm are present in the metamorphosed syenite. The crystals are generally dipyramidal and yellowish-brown in color. Zircon is very hard (7.5) with conchoidal fractures and an adamantine to vitreous luster. Positive identification of this mineral was made by using the X-ray diffractometer in the laboratory. Ankerite - CaFe(CO3)2 (Calcium Iron Carbonate)

Ankerite occurs as semi-rhombohedral crystals with slightly curved faces, and as compact, fine-grained aggregates. It has a hardness of 3.5 - 4.0 and a vitreous to pearly luster. Ankerite is generally a yellowish- white color, but oxidation may cause it to be a yellowish-brown. This mineral is very similar to dolomite, both physically and chemically, except for the color. Positive identification was made with the use of the X-ray diffractometer in the laboratory. Arsenopyrite - FeAsS (Iron Arsenic Sulfide) Arsenopyrite is present mainly as granular aggregates, but some elongated prismatic crystals with striated faces can be found. It is hard (5.5 - 6.0), has a high specific gravity, metallic luster, a black streak, and is silverygray in color. Identification was verified using the X-ray diffractometer in the laboratory. Augite - (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 (Calcium Magnesium Iron Aluminum Silicate) Augite is present as stubby, prismatic crystals, as well as granular aggregates in the gabbro. The physical properties vary from sample to sample because augite is an intermediate member of a solid solution series between Ca-rich diopside and Fe-rich hedenbergite end members. It is hard (5.0 - 6.0) with two distinct cleavage directions at approximately 90deg. and a splintery type fracture. Augite can also be identified by its vitreous to resinous luster, greenish-gray streak, and greenish-black color. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 (Hydrous Potassium Aluminum Silicate) Biotite occurs as foliated, platy aggregates in the metamorphic rocks. The crystals range in size from <1 mm to 3 mm across and are found in the rocks in the hydrothermal veins. Biotite can be identified by its perfect basal cleavage, vitreous luster, flexible sheets, and brownish- black color. Chalcopyrite - CuFeS2 (Copper Iron Sulfide) Chalcopyrite occurs as compact granular masses as a result of hydrothermal activity. It has a hardness of 3.5 - 4.0, a high specific

gravity, no cleavage, a greenish-black streak, and a semi-metallic luster. Chalcopyrite is dark, brassy-yellow, and is coated with an iridescent film. Goethite - [[alpha]]-FeOOH (Iron Hydroxide) Goethite is present in the form of amorphous, earthy masses. It is probably formed from the oxidation of iron-bearing minerals. At this location, it is very fragile, with a yellow-brown streak, an earthy luster, and is brown in color. Identification was verified using the X-ray diffractometer in the laboratory. Hematite - Fe2O3 (Iron Oxide) The hematite occurs as compact, earthy masses and as micaceous rhombohedral crystals. The massive form has a hardness of around 5.0, a relatively high specific gravity, an earthy luster, reddish color, and a redbrown streak. Hematite that occurs in the micaceous form has individual rhombohedral crystals. The micaceous hematite is present in two distinct arrangements. One type is referred to as lamellar (as pages in a book), and the second type is an arrangement that resembles flower petals. Both types display a shiny purplish-red iridescence and distinguishable lines similar to striations on the crystal faces. This form of hematite is softer (3.5 - 4.5) than the massive form and is gray to gray-black in color; however, the red-brown streak is the same. Identification of this mineral was verified by X-ray diffraction in the laboratory. Limonite - FeO*OH*nH2O (Hydrated Iron Oxide) Limonite is present in the form of earthy, porous masses and as a crustal material covering the quartzite and filling the pyrite casts. The physical properties of limonite are highly variable owing to varying chemical composition and habit; but at this location, it is yellowish-brown in color with a earthy luster, pale brown to yellow streak, and is very fragile. Microcline/Albite - (Perthite) (K,Na)AlSi3O8 (Potassium Sodium Aluminum Silicate) This sample is not an individual mineral. It occurs as a product of exsolution with a potassium-feldspar-rich host mineral and sodium

plagioclase lamella (layers). It is hard (6.0), shows distinct, nearly right angle cleavage, has a vitreous luster, a white streak, and is blue-gray in color. The crystals are stubby and prismatic with penetration twins rarely visible with a hand lens. Positive identification was attained by the use of the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Pyrite - FeS2 (Iron Sulfide) Pyrite occurs as very small striated cubes and compact granular aggregates. It can be distinguished from chalcopyrite by its higher hardness (6.0 - 6.5), black streak, and bright metallic luster. Pyrite is also a darker yellow color than chalcopyrite. Pyrolusite - MnO2 (Manganese Oxide) Pyrolusite occurs as dendritic, black aggregates resembling small plant fossils (pseudo-fossils) in the fractures of the igneous and metamorphic rocks. The dendritic form is common, but some small samples (~ 1 cm across) in the form of black, earthy masses can also be found. Pyrolusite is hard (6.0 - 6.5) with a relatively high specific gravity, sub-metallic luster, and a blue-black streak. Quartz - SiO2 (Silicon Oxide) Quartz is present as massive, microcrystalline masses in the igneous rocks, and as very small hexagonal crystals in the fractures and voids as a result of hydrothermal activity. It is also abundant throughout the tailings piles. The quartz that has been exposed and weathered is coated with a yellow or red-brown iron stain, whereas freshly broken samples are of the smoky-quartz or milky-quartz variety. It is hard (7.0), shows no cleavage but conchoidal fractures are evident, and has a vitreous luster. Actinolite - Ca2(Mg,Fe)5Si8O22(OH)2 (Hydrous Calcium Magnesium Iron Silicate) Actinolite occurs as elongated prismatic crystals in both the metamorphic and igneous rocks. The color ranges from a light to dark green, and the crystals exhibit perfect cleavage parallel to the elongation direction.

Actinolite is hard (5.0 - 6.0) with a vitreous to silky luster. Actinolite also occurs in a fibrous form with the same physical properties. Positive identification was attained by the use of the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Apatite - Ca5(PO4)3(F,Cl,OH) (Calcium Phosphate) Apatite occurs as hexagonal prismatic crystals in hydrothermal veins. The crystals are stubby, commonly terminated by pyramidal faces, and range in size from 1 mm to 3 mm long. Apatite has a hardness of 5.0, with a vitreous luster, a white streak, and is greenish-white in color. X-ray diffraction in the laboratory provided positive identification of this mineral. Augite - (Ca,Na)(Mg,Fe,Al,Ti,)(Si,Al)2O6 (Calcium Magnesium Iron Aluminum Silicate) The augite at this location most commonly occurs as granular greenishblack or greenish-brown aggregates, although short, stubby, nearly square crystals are not uncommon. The visible crystals range in size from 1 mm to 5 mm across. Augite is relatively hard (5.0 - 6.0) with two cleavage directions at approximately 90deg. and splinter type fractures. Augite exhibits a dull vitreous luster, has a gray-green streak, and is generally some shade of green in color. X-ray diffraction in the laboratory provided positive identification of this mineral. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 (Hydrous Potassium Aluminum Silicate) Biotite occurs as foliated, platy aggregates in the metamorphic rocks. The crystals range in size from <1 mm to 3 mm across and are found in the rocks in the hydrothermal veins. Biotite can be identified by its perfect basal cleavage, vitreous luster, flexible sheets, and brownish- black color. Epidote - Ca2(Al,Fe)3Si3O12(OH) (Hydrous Calcium Aluminum Iron Silicate)

Epidote is present in several forms in the contact metamorphic rocks. The most common forms are fibrous and granular masses, but small prismatic, greenish crystals with striated faces can be found. Epidote is hard (6.0 7.0) with distinct cleavage parallel to elongation direction of the crystals. It is generally various shades of green and has a vitreous luster. Goethite - [[alpha]]-FeOOH (Iron Hydroxide) The goethite at Stop #1 is present as a pseudomorph after pyrite. The external characteristics of the pyrite crystals have been retained, but the pyrite has altered to goethite. Goethite has a hardness of 5.0 - 5.5, an earthy luster, a greasy feel, and is a brownish-yellow color. Hematite - Fe2O3 (Iron Oxide) The hematite occurs as compact, earthy masses and as micaceous rhombohedral crystals. The massive form has a hardness of around 5.0, a relatively high specific gravity, an earthy luster, reddish color, and a redbrown streak. Hematite that occurs in the micaceous form has individual rhombohedral crystals. The micaceous hematite is present in two distinct arrangements. One type is referred to as lamellar (as pages in a book), and the second type is an arrangement that resembles flower petals. Both types display a shiny purplish-red iridescence and distinguishable lines similar to striations on the crystal faces. This form of hematite is softer (3.5 - 4.5) than the massive form and is gray to gray-black in color; however, the red-brown streak is the same. Identification of this mineral was verified by X-ray diffraction in the laboratory. Hornblende - (Ca,Na)2-3(Mg,Fe2+,Fe3+,Al)5(Al,Si)8O22(OH)2 (Complex double chain silicate; amphibole) Hornblende is present, along with the actinolite, in the syenite, in the form of short, stubby, black, prismatic crystals. They are hard (5.0 - 6.0) with uneven fractures, good prismatic cleavage, a vitreous luster, and a yellow-white streak. Positive identification was attained by the use of the X-ray diffractometer in the laboratory. Limonite - FeO*OH*nH2O (Hydrated Iron Oxide)

Limonite is present in the form of earthy, porous masses and as a crustal material covering the quartzite and filling the pyrite casts. The physical properties of limonite are highly variable owing to varying chemical composition and habit; but at this location, it is yellowish-brown in color with a earthy luster, pale brown to yellow streak, and is very fragile. Malachite - Cu2(CO3)(OH)2 (Hydrous Copper Carbonate) Malachite commonly occurs as a green film on the copper-containing quartz veins. It is found mostly in granular masses, but some radiating crystal aggregates are present. Malachite is semi-hard (3.5 - 4.0), displays good cleavage, has a vitreous to silky luster, a light green streak, and is varying hues of green in color. It is commonly associated with azurite, but azurite was not found. Microcline/Albite - (Perthite) (K,Na)AlSi3O8 (Potassium Sodium Aluminum Silicate) This sample is not an individual mineral. It occurs as a product of exsolution with a potassium-feldspar-rich host mineral and sodium plagioclase lamella (layers). It is hard (6.0), shows distinct, nearly right angle cleavage, has a vitreous luster, a white streak, and is white in color. The crystals are large, ranging in size from approximately 2 cm wide to as much as 5 cm long, up to very large (2 cm wide and 10 cm long) crystals in the syenite. Positive identification was attained by the use of the X-ray diffractometer, and the Scanning Electron Microscope in the laboratory. Pyrite - FeS2 (Iron Sulfide) Pyrite occurs as very small striated cubes and compact granular aggregates, mainly in the quartz in the hydrothermal veins. It can be distinguished from chalcopyrite by its higher hardness (6.0 - 6.5), black streak, and bright metallic luster. Pyrite is also a darker yellow color than chalcopyrite. Quartz - SiO2 (Silicon Oxide) Quartz is present as massive, compact, concretionary masses in the igneous rocks, and as very small hexagonal crystals in the fractures and

voids as a result of hydrothermal activity. The quartz that has been exposed and weathered is coated with a yellow or red-brown iron stain, whereas freshly broken samples are milky-quartz. It is hard (7.0), shows no cleavage but conchoidal fractures are evident, and has a vitreous luster. Titanite (Sphene) - CaTiSiO5 (Calcium Titanium Silicate) Titanite is present in the igneous rocks and metamorphic contacts as flat, stubby, wedge-shaped crystals. It is relatively hard (5.0 - 5.5), has a fairly high specific gravity, an adamantine or resinous luster, and is a honeybrown color. X-ray diffraction in the laboratory provided positive identification of this mineral. Albite/Microcline - (Antiperthite) (Na,K)AlSi3O8 (Sodium Potassium Aluminum Silicate) This sample is not an individual mineral. It occurs as a product of exsolution with a sodium-plagioclase-rich host mineral and potassium feldspar lamella (layers). It is hard (6.0), shows distinct, nearly right angle cleavage, has a vitreous luster, a white streak and is grayish-pink in color. The crystals are bladed, with striations visible with a hand lens only on rare specimens. Positive identification was attained by the use of the Xray diffractometer and the Scanning Electron Microscope in the laboratory. Chalcopyrite - CuFeS2 (Copper Iron Sulfide) Chalcopyrite occurs as compact granular masses as a result of hydrothermal activity. It has a hardness of 3.5 - 4.0, a high specific gravity, a greenish-black streak, and a semimetallic luster. Chalcopyrite is dark, brassy-yellow in color and is coated with an iridescent film. Ferroactinolite - Ca2Fe5Si8O22(OH)2 (Calcium Iron Silicate) Ferroactinolite occurs as aggregates of elongated prismatic crystals in the mafic metamorphic rocks and intrusive igneous gabbro. It has a hardness of 5.0 - 6.0, perfect 60deg./120deg. prismatic cleavage, a vitreous luster,

and is greenish-black in color. It is the iron-rich end-member of the tremolite-actinolite-ferroactinolite solid-solution series. Gold - Au (Native Element) Gold is present, in minute amounts, as very small, shapeless grains and flakes. It is fairly soft (2.5 - 3.0) and malleable. The gold occurs in pyrite casts where the pyrite and limonite have weathered out, leaving the gold along the sides and base of the cast. Hematite - Fe2O3 (Iron Oxide) The hematite occurs as compact, earthy masses and as micaceous rhombohedral crystals. The massive form has a hardness of around 5.0, a relatively high specific gravity, an earthy luster, reddish color, and a redbrown streak. Hematite that occurs in the micaceous form has individual rhombohedral crystals. The micaceous hematite is present in two distinct arrangements. One type is referred to as lamellar (as pages in a book), and the second type is an arrangement that resembles flower petals. Both types display a shiny purplish-red iridescence and distinguishable lines similar to striations on the crystal faces. This form of hematite is softer (3.5 - 4.5) than the massive form and is gray to gray-black in color; however, the red-brown streak is the same. Identification of this mineral was verified by X-ray diffraction in the laboratory. Microcline/Albite - (Perthite) (K,Na)AlSi3O8 (Potassium Sodium Aluminum Silicate) This sample is not an individual mineral. It occurs as a product of exsolution with a potassium-feldspar-rich host mineral and sodium plagioclase lamella (layers). It is hard (6.0), shows distinct, nearly right angle cleavage, has a vitreous luster, a white streak and is blue-gray in color. The crystals are stubby and prismatic with penetration twins visible with a hand lens on rare specimens. Positive identification was attained by the use of the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Pyrite - FeS2 (Iron Sulfide)

Pyrite occurs as very small striated cubes and compact granular aggregates. It can be distinguished from chalcopyrite by its higher hardness (6.0 - 6.5), black streak, and bright metallic luster. Pyrite is also a darker yellow color than chalcopyrite. Quartz - SiO2 (Silicon Oxide) Quartz is present as massive, microcrystalline masses in the igneous rocks, and as very small hexagonal crystals in the fractures and voids as a result of hydrothermal activity. It is also abundant throughout the tailings piles. The quartz that has been exposed and weathered is coated with a yellow or red-brown iron stain, whereas freshly broken samples are of the smoky-quartz or milky-quartz variety. It is hard (7.0), shows no cleavage but conchoidal fractures are evident, and has a vitreous luster. Sulfur - S (Native Element) Sulfur occurs as very fine granular aggregates and encrustations, which are probably an alteration product of pyrite. It has a yellowish-brown color, very soft (1.5 - 2.5), extremely fragile with poor cleavage, and has a resinous to earthy luster. Identification of this mineral was verified by Xray diffraction in the laboratory. Titanite (sphene) - CaTiSiO5 (Calcium Titanium Silicate) Titanite is present in the igneous rocks as flat, stubby, wedge-shaped crystals. It is relatively hard (5.0 - 5.5), has a fairly high specific gravity, an adamantine or resinous luster, and is a honey-brown color. X-ray diffraction in the laboratory provided positive identification of this mineral. Aragonite - CaCO3 (Calcium Carbonate) Aragonite occurs as small, acicular (needle-like), radiating crystals within the vugs of the basalt. These elongated prismatic crystals are semi-hard (3.5 - 4.0) and very fragile with a vitreous luster, a white streak, and a brownish-yellow to white color. Calcite - CaCO3 (Calcium Carbonate)

The calcite is yellowish to white and is found as a secondary coating or filling in the fractures in the basalt. Calcite is easily identified by its concretionary form, hardness (3.0), and effervescent reaction with dilute hydrochloric acid. Hematite - Fe2O3 (Iron Oxide) Hematite occurs as compact, granular masses. It is relatively hard (5.5 6.5), has a high specific gravity, exhibits no cleavage, has an earthy luster, produces a red-brown streak, and is a deep red color. Labradorite (plagioclase) - (Ca,Na)AlSi3O8 (Calcium, Sodium Aluminum Silicate) The plagioclase feldspar present at this location is a solid solution between anorthite and albite end-members and contains equal amounts of calcium and sodium. The elongated, white to yellow to yellowish- green crystals are small (~ 2 mm long and 0.5 mm across), and display a slight play on colors giving off an iridescent blue color. Plagioclase has a hardness of 6.0, a vitreous to pearly luster, nearly perfect 90deg. cleavage, and striations on some crystal faces. Positive identification was made by using the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Limonite - FeO*OH*nH2O (Hydrated Iron Oxide) Limonite is present in the form of earthy, porous masses and as a crustal material covering the basalt. The physical properties of limonite are highly variable owing to varying chemical composition and habit, but at this location it is yellowish-brown in color with a earthy luster, pale brown to yellow streak, and is very fragile. Nontronite - Na0.3Fe2(Al,Si)4O10(OH)2(H2O)4 (Clay Mineral) Nontronite is a secondary mineral formed by the weathering of the aluminum silicates in the basalt. It occurs as microcrystalline masses filling the vugs in the basalt. It is extremely soft (1.5 - 2.0) and commonly has a dull or earthy luster, except on very fresh surfaces, where a vitreous luster is displayed. As soon as the samples are exposed to the atmosphere,

the luster quality decreases and the color changes from a pale blue to a dull greenish blue. The identification of this mineral was verified using the X-ray diffractometer in the laboratory. Olivine - (Mg,Fe)2SiO4 (Magnesium Iron Silicate) The olivine at this location occurs mainly as very small crystals in the basalt. However, it can also be found as small, stubby, prismatic crystals that are visible with the naked eye or with a hand lens. Olivine has a hardness of 6.5 - 7.0, conchoidal fractures, a vitreous luster, and is yellow-green or olive-green in color. Opal - SiO2*nH2O (Hydrous Silicon Oxide) The white or clear opal is found in a massive microcrystalline form filling the vugs in the basalt. The differences in color of the opal samples may be due to varying impurities in the specimens. Opal is relatively easy to identify. It has a hardness of 5.5 - 6.5, low specific gravity, and a vitreous or greasy luster. It is also fragile with very small conchoidal fractures present in nearly all of the samples. Actinolite - Ca2(Mg,Fe)5Si8O22(OH)2 (Hydrous Calcium Magnesium Iron Silicate) Actinolite occurs as striated, elongated prismatic crystals in both the metamorphic and igneous rocks. The color ranges from a light to dark green, and the crystals exhibit perfect cleavage parallel to the elongation direction. Actinolite is hard (5.0 - 6.0) with a vitreous to silky luster. Actinolite also occurs in a fibrous form with the same physical properties. Positive identification was attained by the use of the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Calcite - CaCO3 (Calcium Carbonate) The calcite is yellowish to white and is found as a secondary coating or filling in the fractures in the metamorphic rocks. Calcite is easily identified by its concretionary form, hardness (3.0), and effervescent reaction with dilute hydrochloric acid. Epidote - Ca2(Al,Fe)3Si3O12(OH)

(Hydrous Calcium Aluminum Iron Silicate) Epidote is present in several forms in the contact metamorphic rocks. The most common forms are fibrous and granular masses, but small prismatic, greenish crystals with striated faces can be found. Epidote is hard (6.0 7.0) with distinct cleavage parallel to elongation direction of the crystals. It is generally various shades of green and has a vitreous luster. Quartz - SiO2 (Silicon Oxide) Quartz is present as massive, microcrystalline masses in the fractures and voids as a result of hydrothermal activity. The quartz that has been exposed and weathered is coated with a yellow or red-brown iron stain, wheras freshly broken samples are milky-quartz. It is hard (7.0), shows no cleavage but conchoidal fractures are evident, and it has a vitreous luster. Scapolite - (Na,Ca,K)4Al3(Al,Si)3Si16O24(Cl,SO4,CO3) (Complex Silicate) Scapolite occurs as microgranular masses or aggregates in and on the metamorphic rocks at this site. Some very small prismatic crystals can be seen with the aid of a hand lens. Scapolite has a hardness of 5.0 - 6.5, very poor cleavage, a dull vitreous luster, and is grayish-white in color. Positive identification was attained by the use of the X-ray diffractometer in the laboratory. Pyrolusite - MnO2 (Manganese Oxide) Pyrolusite occurs as dendritic, black aggregates resembling small plant fossils (pseudo-fossils). The dendritic form is the most common type, but some small samples (~ 1 mm across) in the form of black, earthy masses can also be found. Pyrolusite is hard (6.0 - 6.5) with a relatively high specific gravity, sub metallic luster, and a blue-black streak. Red Opal - SiO2*nH2O (Hydrous Silicon Oxide) The red opal occurs primarily as botryoidal, globular masses on the outside of the basalt. It also occurs in a fibrous, radiating, acicular form coating the basalt and filling the vugs in the basalts.

White or Clear Opal - SiO2*nH2O (Hydrous Silicon Oxide) The white or clear opal is found as botryoidal, globular masses encrusting the basalt, as well as being present within the vugs in the basalt. The white opal also occurs in a fibrous, radiating, acicular form coating the basalt and filling the vugs in the basalts. The differences in color of the opal samples may be due to varying impurities in the specimens. Opal is relatively easy to identify. It has a hardness of 5.5 - 6.5, low specific gravity, and a vitreous or greasy luster. It is also fragile with very small conchoidal fractures present in nearly all of the samples. Wood Opal - SiO2*nH2O (Hydrous Silicon Oxide) This variety of opal is formed by silica replacement of fibers in fossilized wood. The original texture and detail of the wood material is preserved in mineral form. It is present as microcrystalline masses ranging in size from 2 to 6 cm in diameter. Albite (plagioclase feldspar) - NaAlSi3O8 (Sodium Aluminum Silicate) Albite is present as small bladed crystals or weathered granular masses in the pegmatite. Owing to its size, habit, and similarity to other feldspar minerals, positive identification is very difficult in hand sample. The use of the X-ray diffractometer and observation of the optical properties provided definite identification. Beryl - Be3Al2Si6O18 (Beryllium Aluminum Silicate) Beryl occurs in the pegmatites as hexagonal prisms without terminations. The color varies from yellowish-white to pale-green. The hexagonal crystals vary in size from 1 cm across and 2 to 3 cm in length to as large as 8 cm across and 15 cm long. It is very hard (7.5 - 8.0) with a vitreous luster and a white streak. The samples contain inclusions of quartz, and are weathered, fractured, and fragile. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2

(Hydrous Potassium Aluminum Silicate) Biotite occurs as foliated, platy aggregates in the metamorphic rocks. The crystals range in size from <1 mm to 5 cm and are the primary constituent of the mica schist in this area. Biotite can be identified by its perfect basal cleavage, vitreous luster, flexible sheets, and brownish-black color. Garnet - (almandine-pyrope) - (Fe,Mg)3Al2(SiO4)3 (Iron Magnesium Aluminum Silicate) The garnets found at this location are almandine/pyrope. The samples are in the pegmatite and display distinct dodecahedral crystal form, have a hardness of 6.5 - 7.5, and are bright red in color. The crystals are relatively small, ranging in size from 1 to 3 mm. Positive identification was obtained through the use of X-ray diffraction in the laboratory. Muscovite - KAl2(AlSi3O10)(OH)2 (Hydrous Potassium Aluminum Silicate) Muscovite occurs as foliated, tabular, pseudo-hexagonal crystals in the granite pegmatite and at the contact between the pegmatite and the metamorphic rocks. Some of the sheets are as large as 20 to 30 cm across, although smaller crystals in the 1 to 5 cm range are more common. The muscovite has perfect basal cleavage into thin, flexible, elastic sheets. It is soft (2 - 2.5) and is primarily yellow-brown in color where occurring in thick, foliated books, but clear colored where present in thin sheets. Phlogopite - K(Mg,Fe)3(AlSi3)O10(F,OH)2 (Hydrous Potassium Aluminum Silicate) Phlogopite occurs as very small (~ 1 to 2 mm) plates in the metamorphic rocks. It can be identified by its basal cleavage, vitreous luster, and yellowish-brown color. Quartz - SiO2 (Silicon Oxide) Quartz is present as microcrystalline masses in the pegmatite, as well as being abundant throughout the tailings piles. The quartz that has been

exposed is coated with a yellow or red-brown iron stain, whereas the quartz in the pegmatite is more of the smoky-quartz or milky-quartz variety. It is hard (7.0), shows no cleavage but conchoidal fractures are evident, and has a vitreous luster. Tourmaline (schorl) (Na,Ca) (Mg, Fe2+,Fe3+,Al,Mn,Li)3Al6(B03)3(Si6O18)(OH,F)4 (Complex Borosilicate) The schorl variety of tourmaline is rich in iron and sodium. It occurs as elongated, black prismatic crystals with vertical striations in the mica schist, and short, stubby, black crystals in the pegmatite. The elongated crystals are commonly 1 to 4 mm across and 1 to 2 cm long. Tourmaline is very hard (7.0) with conchoidal fractures and a vitreous luster. The luster changes to resinous on the fractured surfaces. Arsenopyrite - FeAsS (Iron Arsenic Sulfide) Arsenopyrite occurs as slightly elongated prismatic crystals ranging in size from 1 mm to as large as 1 cm, and granular aggregates in the hydrothermal vein and metamorphic rocks. It is relatively hard (5.5 - 6.0) with a metallic luster and a black streak. Azurite - Cu3(CO3)2(OH)2 (Hydrous Copper Carbonate) Azurite occurs as very small, striated, tabular, prismatic, radiating, intergrown crystals in the rocks found in the hydrothermal veins, and as a granular film coating the copper-bearing metamorphic rocks. This secondary copper mineral is semi-hard (3.5 - 4.0), displays good cleavage with a vitreous luster and a pale blue streak. It is commonly associated with malachite. Positive identification was attained by the use of the Xray diffractometer in the laboratory. Bornite - Cu5FeS4 (Copper Iron Sulfide) Bornite can be found as octahedral crystals at this location, but it is more likely to be found as compact granular masses. It commonly displays a reddish-bronze color, which is tarnished to an iridescent purple and blue film. The old miners referred to bornite as "Peacock Ore." Bornite has a

hardness of 3.0, a high specific gravity, a gray-black streak, and a metallic luster. Brochantite - Cu4(SO4)(OH)6 (Hydrous Copper Sulfate) Brochantite is present in granular form in veins in the adit, although some small prismatic crystals (~2 mm) can be found. It is light blue-green in color with a vitreous to pearly luster and a light green streak. The brochantite is very weathered, fragile, and difficult to identify in hand sample owing to its physical similarity to other copper sulfate and copper carbonate minerals. Identification of this mineral was verified by X-ray diffraction in the laboratory. Chalcocite - Cu2S (Copper Sulfide) Chalcocite exists primarily in the form of granular aggregates in the hydrothermal sulfide deposit. It is soft (2.5) with a metallic luster, a dark gray streak, and conchoidal fractures. It commonly is associated with cuprite, malachite, and azurite. Tabular crystals with striated faces can be found, but they are uncommon. Chalcopyrite - CuFeS2 (Copper Iron Sulfide) Chalcopyrite occurs as compact granular masses as a result of hydrothermal activity and metamorphism. It has a hardness of 3.5 - 4.0, a high specific gravity, lacks cleavage, a greenish-black streak, and a semimetallic luster. Chalcopyrite is dark, brassy yellow in color and is coated with an iridescent film. X-ray diffraction in the laboratory provided positive identification of this mineral. Cuprite - Cu2O (Copper Oxide) Cuprite is present in the form of very small (< 1 mm) elongated cubic/dodecaheral crystals. It has a hardness of approximately 4.0 with a dull adamantine luster and a bright red streak. Cuprite is a dark red color and is altered to malachite on exposed surfaces. X-ray diffraction in the laboratory provided positive identification of this mineral. Copper - Cu (Native Element)

Small amounts of copper can be found as compact, filiform masses. It displays the characteristic copper-red color on fresh surfaces. However, most samples are coated with a greenish malachite film or a blackish or iridescent film. Copper is soft (2.5 - 3.0), very heavy, and malleable with a metallic luster. Hematite - Fe2O3 (Iron Oxide) Hematite occurs as compact, granular masses. It is relatively hard (5.5 6.5), has a high specific gravity, exhibits no cleavage, has an earthy luster, produces a red-brown streak, and is a deep red color. Limonite - FeO*OH*nH2O (Hydrated Iron Oxide) Limonite is present in the form of earthy, porous masses and as a crustal material covering the metamorphic rocks. The physical properties of limonite are highly variable owing to varying chemical composition and habit, but at this location, it is yellowish-brown in color with an earthy luster, pale brown to yellow streak, and is very fragile. Malachite - Cu2(CO3)(OH)2 (Hydrous Copper Carbonate) Malachite commonly occurs as a green film on the copper-containing metamorphic rocks. It is found mostly in granular masses, but some radiating crystal aggregates are present. Malachite is semi-hard (3.5 4.0), displays good cleavage, has a vitreous to silky luster, a light green streak, and is varying hues of green. It is commonly associated with azurite. Positive identification was attained by the use of the X-ray diffractometer in the laboratory. Pyrite - FeS2 (Iron Sulfide) Pyrite occurs as very small striated cubes and compact granular aggregates. It can be distinguished from chalcopyrite by its higher hardness (6.0 - 6.5), black streak, and bright metallic luster. Pyrite is also a darker yellow color than chalcopyrite. X-ray diffraction in the laboratory provided positive identification of this mineral. Pyrrhotite - Fe1-xS (Iron Sulfide)

Pyrrhotite occurs mainly as massive, granular aggregates in the hydrothermal vein and the metamorphic rocks surrounding the mine. Very small tabular crystals are less common. It has a hardness of around 4.0, a metallic luster, is slightly magnetic, and is bronzish- black in color. Quartz - SiO2 (Silicon Oxide) Quartz is present as microcrystalline masses in the fractures and contacts as a result of hydrothermal activity. It is also abundant throughout the tailings piles. The quartz that has been exposed and weathered is coated with a yellow or red-brown iron stain, whereas freshly broken samples are of the smoky-quartz or milky-quartz variety. It is hard (7.0), shows no cleavage, but conchoidal fractures are evident, and has a vitreous luster. Staurolite - (Fe,Mg,Zn)2Al9Si4O23(OH) (Hydrous Iron Magnesium Aluminum Silicate) Staurolite occurs as prismatic crystals, up to 4 cm long, in the schist surrounding the mine site. The surface of the mineral is covered with a dull earthy coating resulting from alteration processes. Removing the coating reveals crystals that are brownish- black in color, display a resinous or vitreous luster, and have a hardness of about 7.0. Single crystal occurrences are the most common, but samples exhibiting cruciform twinning can be found. Tourmaline (schorl) (Na,Ca) (Mg, Fe2+,Fe3+,Al,Mn,Li)3Al6(B03)3(Si6O18)(OH,F)4 (Complex Borosilicate) The schorl variety of tourmaline is rich in iron and sodium. It occurs as elongated, black prismatic crystals with vertical striations in the mica schist. The elongated crystals are commonly 1 to 4 mm across and 0.5 to 1 cm long, and are in the form of radiating or parallel aggregates. Tourmaline is very hard (7.0) with conchoidal fractures and a vitreous luster. The luster changes to resinous on the fractured surfaces. Zinnwaldite (?) - KLiFe3+Al(AlSi3)O10(F,OH)2

(Hydrous Potassium Aluminum Silicate) Zinnwaldite is present as tabular or bladed crystals in the hydrothermal vein in conjunction with quartz. It is soft (2.5 - 3.0) with prominent basal cleavage, a vitreous to greasy luster, and is silvery-black in color. Xray diffraction patterns match those for zinnwaldite, but chemical analysis is needed for positive identification. Chabazite - Ca(Al2Si4)O12*6H2O (Hydrated Calcium Aluminum Silicate) Chabazite occurs as rhombohedral crystals within vugs and fractures of the basalt. It is semi-hard (4 - 5), with rhombohedral cleavage, vitreous luster, and a white streak. The crystals are very large, commonly 3 to 5 mm across, with some being as large up to 1 cm in diameter and white in color with penetration twinning in all the samples. Green chabazite is also found in massive form underneath the white rhombohedral crystals. Identification of this mineral was verified by X-ray diffraction in the laboratory. Labradorite (plagioclase) - (Ca,Na)AlSi3O8 (Calcium, Sodium Aluminum Silicate) The plagioclase feldspar found at this location is a solid solution between anorthite and albite end-members and contains equal amounts of calcium and sodium. The elongated, white to yellow-white to yellow-green crystals range in size from 3 mm long and 1 mm wide up to 2 cm long and 1 cm wide, and display a slight play on colors yielding an iridescent blue. Plagioclase has a hardness of 6.0, a vitreous to pearly luster, nearly perfect 90deg. cleavage, and striations on some crystal faces. Positive identification was made by using the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Pyrite - FeS2 (Iron Sulfide) Pyrite is a secondary mineral occurring in the form of very small cubic crystals on the basalt. It can be identified by its brassy yellow color and cubic habit.

Actinolite - Ca2(Mg,Fe)5Si8O22(OH)2 (Hydrous Calcium Magnesium Iron Silicate) Actinolite occurs as elongated prismatic crystals in the metamorphic rocks. The color ranges from a light to dark green, and the crystals exhibit perfect cleavage parallel to the elongation direction. Actinolite is hard (5.0 - 6.0) with a vitreous to silky luster. Actinolite also occurs in a fibrous form with the same physical properties. Positive identification was attained by the use of the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Apatite (fluorapatite) - Ca5(PO4)3(F) (Phosphate) Apatite occurs as hexagonal prismatic crystals in alkaline feldspar granite. The crystals are stubby and commonly terminated by pyramidal faces, and range in size from 1 mm to 3 mm long. Apatite has a hardness of 5.0, with a vitreous luster, a white streak, and is greenish-white in color. X-ray diffraction in the laboratory provided positive identification of this mineral. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 (Hydrous Potassium Aluminum Silicate) Biotite occurs as foliated, platy aggregates in the metamorphic rocks and as disseminated plates in the granite. The crystals range in size from <1 mm to 3 mm across. Biotite can be identified by its perfect basal cleavage, vitreous luster, flexible sheets, and brownish-black color. Limonite - FeO*OH*nH2O (Hydrated Iron Oxide) Limonite is present in the form of earthy, porous masses and as a crustal material covering the quartzite. The physical properties of limonite are highly variable owing to varying chemical composition and habit, but at this location, it is yellowish-brown in color with a earthy luster, pale brown to yellow streak, and very fragile. Microcline - KAlSi3O8 (Potassium Aluminum Silicate)

Microcline occurs as small prismatic crystals and as granular aggregates in the alkaline feldspar granite and as large 6 to 10 cm long crystals in the granite pegmatite. Microcline is hard (6.0 - 6.5), has nearly right angle cleavage, a vitreous luster, a white streak, and is pinkish-white in color. Identification was verified by the use of the X-ray diffractometer in the laboratory. Muscovite - KAl2(AlSi3O10)(OH)2 (Hydrous Potassium Aluminum Silicate) Muscovite occurs as foliated, tabular, pseudo-hexagonal crystals in the granitic rocks. The crystals are in the 1 to 5 cm range. Muscovite has perfect basal cleavage and thin, flexible, and elastic sheets. It is soft (2 2.5) and is primarily yellow-brown in color in thick, foliated books, but clear where found in thin sheets. Phlogopite - K(Mg,Fe)3(AlSi3)O10(F,OH)2 (Hydrous Potassium Aluminum Silicate) Phlogopite mica occurs as very small (~ 1 mm) six-sided plates in the granititic rocks. It displays perfect basal cleavage with vitreous or pearly luster, and is a yellowish-brown color. Pyrolusite - MnO2 (Manganese Oxide) Pyrolusite occurs as dendritic, black aggregates resembling small plant fossils (pseudo-fossils). The dendritic form is the most common type, but some small samples (~ 1 mm across) in the form of black, earthy masses can also be found. Pyrolusite is hard (6.0 - 6.5) with a relatively high specific gravity, sub-metallic luster, and a blue-black streak. Quartz - SiO2 (Silicon Oxide) Quartz occurs as small microcrystalline grains in the alkaline feldspar granite and as large massive aggregates in the granite pegmatite. The quartz that has been exposed and weathered is coated with a yellow or red-brown iron stain, whereas freshly broken samples are of the smoky-

quartz or milky-quartz variety. It is hard (7.0), shows no cleavage, but conchoidal fractures are evident, and has a vitreous luster. Titanite (sphene) - CaTiSiO5 (Calcium Titanium Silicate) Titanite is present in the alkaline feldspar granite as small, (< 1 mm) flat, stubby, wedge-shaped crystals. It is relatively hard (5.0 - 5.5), has a fairly high specific gravity, an adamantine or resinous luster, and is a honeybrown color. X-ray diffraction in the laboratory provided positive identification of this mineral. Tremolite - Ca2Mg5Si8O22(OH)2 (Hydrous Calcium Magnesium Silicate) Tremolite occurs as elongated prismatic crystals in the metamorphic rocks. The color ranges from a light green to white and the crystals exhibit perfect cleavage parallel to the elongation direction. Tremolite is hard (5.0 - 6.0) with a vitreous to silky luster. Tremolite also occurs in a fibrous form with the same physical properties. Positive identification was attained by the use of the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Calcite - CaCO3 (Calcium Carbonate) The calcite is yellowish to white and is found as a secondary coating or filling in the fractures in the basalts. Calcite is easily identified by its concretionary form, hardness (3.0), and effervescent reaction with dilute hydrochloric acid. Goethite - [[alpha]]-FeOOH (Iron Hydroxide) Goethite occurs as a thin, brown, poorly crystalline coating over the botryoidal siderite. It can be distinguished from siderite by its higher degree of hardness (5.0 - 5.5) and dark brown to black color. X-ray diffraction analysis verified the identification. Brown Opal - SiO2 * nH2O (Hydrous Silicon Oxide) The brown opal can be found in microcrystalline masses ranging in size from granular to 4 to 6 cm in diameter.

Black Opal - SiO2 * nH2O (Hydrous Silicon Oxide) The black opal is also found as microcrystalline masses which range in size from granular to 4 to 6 cm in diameter. White Opal - SiO2 * nH2O (Hydrous Silicon Oxide) The white opal occurs mainly in globular masses on the outside of the basalt. The three varieties of 'opal' are identifiable in the field. Opal has a hardness of 5.5 - 6.5 with a relatively low specific gravity. It has a vitreous or greasy luster, and conchoidal fractures are common on nearly all samples. The differences in color of the samples may be due to varying impurities in the specimen. The three samples also have varying crystallinity based upon X-ray analysis. Siderite - FeCO3 (Iron Carbonate) Siderite is found as botryoidal globular masses within the vugs in the basalt. It has a hardness of 3.5 - 4.0 with a bright vitreous luster and a white streak. The color varies from a very pale brown to a pale yellow. The spheres are thinly coated with brown goethite, and range in size from 1 to 5 mm. Identification of this mineral was verified by the use of X-ray diffraction in the laboratory. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 (Hydrous Potassium Aluminum Silicate) Biotite mica occurs as relatively small (~ 5 mm) disseminated plates or platy aggregates in the sillimanite-mica schist. The individual plates are flexible and elastic with very pronounced vitreous luster. They also have perfect basal cleavage and are blackish-brown in color. Brochantite - Cu4(SO4)(OH)6 (Hydrous Copper Sulfate) Brochantite is present in granular form in veins in the adit, although some small prismatic crystals (~2 mm) are present. It is light blue-green in color with a vitreous to pearly luster and a light green streak. The brochantite is very weathered, very fragile, and difficult to identify in

hand sample owing to its physical similarity to other copper sulfate and copper carbonate minerals. Identification of this mineral was verified by X-ray diffraction in the laboratory. Garnet - (Fe,Mg)3Al2(SiO4)3 (Iron, Magnesium Aluminum Silicate) The garnets present at this location have almandine/pyrope chemistry. They are present in schistose veins in the adit as large crystals (1 to 3 cm), and in the mica schist around the adit entrance in smaller sizes (1 to 5 mm). The samples from the veins exhibit distinct dodecahedral crystal form, have a hardness of 6.5 - 7.5, and vary in color from dark reddishbrown to purple. The smaller garnets in the schist are brighter red and less weathered than the ones found in the adit, but still have the distinctive crystal form. Positive identification was obtained through the use of Xray diffraction in the laboratory. Muscovite - KAl2(AlSi3O10)(OH)2 (Hydrous Potassium Aluminum Silicate) Muscovite mica occurs as small (~5 mm) thin disseminated plates in the sillimanite-mica schist. These flexible, elastic plates exhibit perfect basal cleavage, prominent vitreous luster, and a silvery or yellowish-white color. Phlogopite - K(Mg,Fe)3(AlSi3)O10(F,OH)2 (Hydrous Potassium Aluminum Silicate) Phlogopite occurs as very small (~ 1 mm) six-sided plates in the sillimanite-mica schist. It displays perfect basal cleavage with vitreous or pearly luster and is yellowish-brown in color. Quartz - SiO2 (Silicon Oxide) Quartz is present as small (1 to 3 mm) gray, granular masses in pegmatite dikes cross-cutting the schist. It can be identified by its hardness (7.0), lack of cleavage, vitreous luster, and pale gray to white color. Sillimanite - Al2SiO5 (Aluminum Silicate)

Sillimanite occurs as long, slender, fibrous crystals within the micasillimanite schists and as individual crystals in veins located inside the adits. The crystals are 0.5 to 1.5 cm long and vary slightly in color from a yellowish-white in the veins to gray in the schist. The yellowish white sillimanite has been weathered and is very fragile, but the crystals in the schist have a hardness of 6 - 7 with a vitreous or pearly luster. Albite (plagioclase) - NaAlSi3O8 (Sodium Aluminum Silicate) Albite occurs as small prismatic or bladed crystals in the granodiorite. The crystals are commonly 1 to 2 mm long and 0.5 to 1 mm wide with striations visible, with the aid of a hand lens, on some fresh surfaces. Albite is hard (6.0 - 6.5) with nearly right angle cleavage, a vitreous luster, and a white streak. The color of albite varies, at this location, from a very pale green to a greenish-white. Positive identification was attained by the use of the X-ray diffractometer in the laboratory. Biotite - K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 (Hydrous Potassium Aluminum Silicate) Biotite occurs as foliated, platy aggregates and as individual thin sheets in the granodiorite. The crystals range in size from <1 mm in the granodiorite to 5 cm across in the pegmatites. Biotite can be identified by its perfect basal cleavage, vitreous luster, flexible sheets, and brownishblack color. Garnet - (almandine-pyrope) - (Fe,Mg)3Al2(SiO4)3 (Iron Magnesium Aluminum Silicate) The garnets found at this location have almandine/pyrope chemistry. The samples are in the pegmatite and display distinct dodecahedral crystal form, have a hardness of 6.5 - 7.5 and are bright red in color. The crystals are relatively small, ranging in size from 1 to 3 mm. Positive identification was obtained through the use to X-ray diffraction in the laboratory. Limonite - FeO*OH*nH2O (Hydrated Iron Oxide)

Limonite is present in the form of earthy, porous masses and as a crustal material covering the granitic rocks and filling in the voids created by fracturing. The physical properties of limonite are highly variable owing to varying chemical composition and habit, but at this location it is yellowish-brown in color with a earthy luster, pale brown to yellow streak, and very fragile. Microcline/Albite - (Perthite) (K,Na)AlSi3O8 (Potassium Sodium Aluminum Silicate) This sample is not an individual mineral. It occurs as a product of exsolution with a potassium-feldspar-rich host mineral and sodium plagioclase lamella (layers). It is hard (6.0), shows distinct, nearly right angle cleavage, has a vitreous luster, a white streak and is white in color. The crystals are large, ranging in size from approximately 2 cm wide to as much as 5 cm long. Positive identification was attained by the use of the X-ray diffractometer and the Scanning Electron Microscope in the laboratory. Muscovite - KAl2(AlSi3O10)(OH)2 (Hydrous Potassium Aluminum Silicate) Muscovite occurs as foliated, tabular, pseudo-hexagonal crystals in the granodiorite. Some are as large as 5 to 8 cm across, although smaller crystals in the 1 to 5 cm range are more common. The muscovite has perfect basal cleavage in thin, flexible, elastic sheets. It is soft (2 - 2.5) and is primarily a yellow-brown color in thick, foliated books, but clear where found in thin sheets. Pyrite - FeS2 (Iron Sulfide) Pyrite occurs as very small striated cubes and compact granular aggregates. It can be distinguished from chalcopyrite by its higher hardness (6.0 - 6.5), black streak, and bright metallic luster. Pyrite is also a darker yellow color than chalcopyrite. Quartz - SiO2 (Silicon Oxide)

Quartz is present as massive, microcrystalline masses in the igneous rocks, and as very small hexagonal crystals in the fractures and voids as a result of hydrothermal activity. It is also abundant throughout the tailings piles. The quartz that has been exposed and weathered is coated with a yellow or red-brown iron stain, whereas freshly broken samples are of the smoky-quartz or milky-quartz variety. It is hard (7.0), shows no cleavage but conchoidal fractures are evident, and has a vitreous luster. BELT SUPERGROUP ROCKS Background Information Meta-sedimentary rocks of the Belt Supergroup extend from western Montana through northern Idaho and into bordering parts of Washington and British Columbia. Lithologically, the rocks of the Belt Supergroup can be described as a thick sequence of alternating argillite, siltite, and quartzite with minor carbonate. The effects of low grade metamorphism are reflected in the recrystallized textures, but the metamorphism has not destroyed the sedimentary features at every outcrop. From bottom to top, the major units of the Belt rocks in northern Idaho are: Prichard, Burke, Revett, St. Regis, Wallace, Striped Peak, and Libby Formations. The Burke, Revett, and St. Regis Formations are members of the Ravalli Group and the Striped Peak and Libby Formations constitute the Missoula Group. The rocks of the Belt Supergroup attain a maximum thickness of 67,000 feet (Harrison, 1972). Rocks of the Belt Supergroup range from approximately 1,450 to 850 million years old; and the sediments forming them were deposited in what may have been a slowly subsiding marginal re-entrant that trends north to northwest, commonly referred to as the Belt Basin (Harrison, 1972). South and southwest of the basin, along the St. Joe River drainage, progressive metamorphism of the Belt rocks has made identification of the units much more difficult. Regionally, metamorphism increases from zeolite facies in the northeast to amphibolite facies in the southwest where pre-Belt and Belt terrains encounter the Idaho Batholith (Hietanen, 1963, 1968; Harrison, 1972; Reid and others, 1973; Reid and others, 1981). The degree of metamorphism also increases downwards in

sections where siltite, argillite, and quartzite have been transformed into recrystallized, foliated schist and quartzose gneiss. However, in most places even with the high metamorphism, the units can be mapped separately (Hietanen, 1963, 1968; Harrison, 1972; and Reid and others, 1981). There is so little variation in rock type, grain size, and color that, to many workers, the Belt rocks are monotonous in appearance (Harrison and Grimes, 1970). However, where metamorphism has not been intense, sedimentary structures such as cross-beds, ripple marks, parallel laminations, load casts, mud cracks, and stromatolites are well preserved. These structures, where present, have been used to help define rock units and to interpret depositional environments. The Belt Supergroup consists of the following five basic rock types: (a) very fine-grained to fine-grained quartzite and arkosic quartzite; (b) siltite and argillitic siltite; (c) laminated black argillite and white or green siltite; (d) argillite and silty argillite; and (e) carbonate rocks. Nearly identical rock types commonly occur in several formations or in at least two members of a single formation. Green to gray-green, thin-bedded to laminated siltite or argillitic siltite is abundant throughout most of the sequence and, therefore, is the least useful of all the rock types for identification of stratigraphic position. Differences among the similar rock units are subtle, but many of these differences are useful for mapping. Individual Latah County Formations There are three specific formations thought to be present in north-central Latah County from the Laird Park area northward to and beyond the Benawah-Latah county line. In the immediate Laird Park vicinity, approximately 3.5 miles east and 2 miles southeast of Harvard, rock types similar to the Wallace and Revett Formations exist. The Wallace Formation is about 10,200 feet thick (Harrison and Jobin, 1965). The formation is the most heterogeneous and is the principal carbonate-bearing formation of the entire Belt sequence. The common rock types are: (a) black and white or green thinly interlaminated argillite and siltite; (b) green siltite thinly interbedded with argillitic green siltite; (c)

blue-gray laminated dolomitic limestone; (d) greenish-gray, very thin bedded dolomitic or calcareous siltite and dolomitic or calcareous argillitic siltite; (e) black laminated silty argillite; (f) white laminated dolomitic quartzite; and (g) laminated waxy green argillite. Outcrops located along the Palouse River Road, from 0.5 to 1.0 mile southeast of the junction with State Highway 6, contain banded argillite and silty argillite along with calcareous, dolomitic, and scapolitic features. The white blebs and masses of scapolite are also indicators of the Wallace Formation. Scapolite is a complex of potassium, calcium, aluminum silicate mineral associated with metamorphosed calcium-rich rocks. An outcrop believed to belong to the Revett Formation is located approximately 1.7 miles from the State 6 junction on the left hand side of the road east of Laird Park. The Revett Formation is about 2,000 feet thick (Harrison and Jobin, 1963). Lithologically it is the most homogenous unit of the Belt Supergroup. The quartzite is mostly finegrained and relatively pure. It is distinguishable by its beds of blocky white to gray, cross-bedded quartzite. Laminated green argillite is also common in the Revett. The sedimentary structures include cross-beds, ripple marks, mudcracks, and mud-chip breccias. The exposure at this location is dominated by blocky, gray quartzite. The quartzite is crosslaminated with bands which may follow depositional bedding laminations. The outcrop displays an excellent cross-sectional view of a large channel approximately twenty feet across. A fault is exposed on the western end of the exposure where the quartzite is highly brecciated across a twenty-five foot thick zone. The third formation thought to exist in Latah county is the Libby Formation. This formation is present mainly in the extreme north-central part of the county south of the North South Ski Bowl. The Libby Formation in this area is an incomplete sequence as its top has been removed by erosion. Exposed portions of this formation consist of laminated black argillite and white siltite, green to gray cherty argillite and siltite that contains carbonate minerals, green to tan silty limestone and dolomite, and a few beds of calcareous and cherty stromatolites and oolites. Mud cracks and ripple marks are abundant throughout the formation, and mud-chip breccia is characteristic of the carbonate-bearing siltites and

argillites. Chert occurs as pale green layers and lenses in laminated green argillite and siltite, as pale green chips in some of the mud-chip breccias, and as black layers or irregular patches that transect layering in the stromatolites and oolites. Oolites, where present, are in beds just below stromatolitic units. IDAHO BATHOLITH Background Information The Idaho Batholith, which occupies much of central Idaho, is approximately 250 miles long and 80 miles wide and it surrounded by regionally metamorphosed rocks (Hamilton and Myers, 1967). The batholith consists of a complex group of plutons which range in age from Cretaceous to Early Tertiary (Armstrong and others, 1977; Bickford and others, 1981). The large body can be subdivided into two separate lobes, the northern Bitterroot lobe and the southern Atlantic lobe. Both regions are underlain by massive granite, granodiorite, and quartz diorite. According to Shuster and Bickford (1985), the most voluminous rock is a weakly foliated, medium-grained two-mica granite with K-feldspar megacrysts. In numerous areas, considerable schist and gneiss are interspersed with the granitic rocks. The contacts between country rocks and the batholith are, in places, wide and generally gradational changing from granite to gneissic granite. The general lithologies and the sequences of the country rocks suggest correlation with the Prichard Formation, Ravalli Group, and the Wallace Formation of the Belt Supergroup (Hyndman and Williams, 1977; Reid and others, 1979). These rocks range from metasedimentary rocks to sillimanite-grade metasedimentary country rocks. Inclusions are common in the granites adjacent to contacts, and the abundance decreases away from those contacts (Shuster and Bickford, 1985). The main phase of igneous intrusion ranges in age from 66 million years to 46 million years (Nelson, 1981). Shuster and Bickford (1985) reported a date of 46 m.y. for one of the youngest intrusions, and Webster and Nunez (1981) reported a date of 67.8 m.y. for granitic rocks near Viola, Idaho north of Moscow.

The origin of the Idaho Batholith is controversial. Shuster and Bickford (1985, p. 738) stated that their date "indicates that the source of the granite was not the exposed intruded country rocks, but was depleted lower crust that is heterogeneous, Proterozoic in age, aluminum rich, and has garnets as a residual phase." Latah County Intrusions In Latah County there is a large area of intrusive rocks that extends across the county from the northeastern corner to the Idaho and Washington state line, north and south of Moscow. These rocks underlie such areas as the Thatuna Hills, Paradise Ridge, Bald Butte, and the Palouse Range. Because this plutonic mass is isolated from, and appears to be independent of the Idaho Batholith, Tullis (1944) referred to these rocks as the Thatuna Batholith. There has not been any detailed work on these rocks since Tullis, but here they are considered to be related to the Idaho Batholith. The dates of 69.8 m.y. and 67.8 m.y. respectively, for rocks from the Palouse Range (Webster and Nunez, 1981) and from Bald Butte (Hooper and Webster, 1982) place them in the Cretaceous and within the age range of the Idaho Batholith. Tullis (1944) reported that granodiorite, adamellite, tonalite, and granite each makeup considerable masses and form the principal intrusions. Typical rocks are light-gray and equigranular but the textures may be gneissic, porphyritic, and pegmatitic. The principal visible minerals are quartz, feldspar, and biotite. Muscovite is common in places, as well as garnet and epidote. Hornblende is present in the quartz-deficient rock types. Microcline, orthoclase, and albite are the principal feldspars. Other lesser rocks include diorite, aplite, granodiorite porphyry and lamprophyre dikes. Granite pegmatite and aplite dikes are locally present and, at times, have been mined for mica in the Avon district near Deary, Idaho. The pegmatite is in contact with schist and minor gneiss of the Belt Supergroup rocks. The beds of schist are gray or silvery white that weather to an iron brown color. Layers of mica gneiss are interbedded with the schist. The introduction of aplite and pegmatite presumably accompanied the intrusion of the underlying Idaho Batholith because narrow dikes and sills cut both the schist and gneiss at several localities.

According to Stoll (1950), there were about 100 pegmatite dikes and sills wider than one foot exposed in trenches, outcrops, pits, and underground workings in the Avon district. The pegmatite seems to be unevenly distributed in the area. Individual bodies lie closely spaced in groups or in a series separated by relatively broad tracts of metamorphic rock containing few pegmatites. Stoll (1950) reported that the district included about 18 mines and prospects that produced mica sheets in quantities ranging from a few pounds to thousands of pounds. The last recorded production, that Stoll was aware of, occurred from 1943 - 1945 when the cost of shipping mica was assumed by the government. In addition to mica, small quantities of beryl were also mined (Stoll, 1950). There are numerous reports on the Avon district pegmatites (Sterrett, 1923; Anderson, 1933; Forrester, 1942; and Stoll, 1950); however, modern research has not been done on either the pegmatites or the underlying batholith. POTATO HILL VOLCANICS Background Information Potato Hill Volcanics consist of Early Tertiary-aged rhyolitic to dacitic lava flows and flow-breccia. The best exposure occurs on Potato Hill located approximately 0.5 mile north of Deary in east-central Latah County. Very little published information on these rocks is available, and good exposures of the sequence are rare. The Potato Hill volcanic rocks rest on an erosion surface cut into granitic rocks of the Idaho Batholith (Jones, 1982). These rocks are predominately Cretaceous granodiorite and are known as the Thatuna Batholith (Bitten, 1951). The similarity between the granodiorite and intrusive clasts contained in the flow-breccias is evidence for a post-Idaho Batholith age for the Potato Hill volcanic rocks. Basalt of the Columbia River Basalt Group overlies the Potato Hill volcanics all around the flanks of Potato Hill. No clasts of Columbia River Basalt have been noted in the flowbreccias. The Potato Hill volcanics can be divided into a lower porphyritic member and an upper flow-breccia member. The lack of exposures prohibits a thickness estimate for the lower member, although Tullis (1944) estimated

it to be 200 to 300 feet thick. The upper flow-breccia member forms the bulk of Potato Hill and has an estimated thickness of approximately 1000 feet (Bitten, 1951; Tullis, 1944). The lower member consists of porphyritic lava flows which are distinguished from the upper member by a general lack of lithic fragments, common presence of flow-layering, and a general lighter color. Compositionally the porphyritic flows were reported to be mainly rhyolite, rhyodacite, and dacite (Bitten, 1951). The lava flows are typically lavender or grayish-white but may be pinkish or brownish-gray. The flows contain between 3% and 10% phenocrysts set in a dense aphanitic groundmass. Locally the flows also contain 1% to 2% lithic fragments. The phenocrysts are predominately 1 mm to 3 mm long milky-white feldspars, with plagioclase being slightly more abundant than K-feldspars (Bitten, 1951). Rounded, anhedral, quartz grains, ranging in size from 0.25 mm to 2.0 mm in diameter, make up the remaining phenocrysts. Outcrops of the lower member weather dark red-brown and are locally stained with iron-oxides, especially along the fractures. Orientation of the fractures is highly variable, and Bitten (1951) described the flows as sheeted masses. Where the flows crop out, flow layering can be determined with close inspection. It can be distinguished by closely spaced, alternating light and dark laminae or bands. These laminae are generally 0.25 to 2.0 millimeters thick. The laminae are subparallel and may be wavy. Individual laminae are observed to wrap around phenocrysts and rare lithic fragments. The upper member consists of an inhomogeneous sequence of dense, dark flow-breccia with distinctive igneous and metamorphic clasts and intercalated lithic-poor lava flows. The flow-breccia is generally matrixsupported and contains variable proportions of angular to rounded clasts of volcanic, intrusive, and metamorphic origin. The matrix is black or brown-gray, devitrified glass and cryptocrystalline material (Bitten, 1951). Although the upper member is dark colored, Bitten (1951) suggested that the phenocryst mineralogy indicates a dacitic to rhyodacitic composition for the flow-breccia. Hand specimens of this member contain between 5% and 20% lithic fragments and 5% to 10% phenocrysts scattered throughout the matrix.

Phenocrysts in the matrix are difficult to distinguish from small lithic fragments or other foreign inclusions. Translucent or white, anhedral to subhedral feldspar phenocrysts are generally 0.5 mm to 2.0 mm in length. The feldspar appears less altered than in the porphyritic flows. Translucent plagioclase may have visible cleavage planes. Potassium feldspar has a whitish color and appears to be slightly less abundant than plagioclase. The anhedral clear crystals range from 0.50 mm to 1.0 mm in diameter. The lithic content of the flow-breccia varies from as high as 50% at an exposure near Bovill, Idaho to 1% in some of the Potato Hill flows. The 1 cm to 10 cm size clasts are generally rounded and generally free of fractures. The volcanic fragments are considered to be the most abundant, followed by intrusive and metamorphic fragments. The volcanic fragments are dark-gray to gray, porphyritic, and closely resemble the porphyritic rocks of the lower member. The light colored intrusive fragments give the flow-breccia a distinctive "polka dot" appearance. Bitten (1951) reported that these fragments are mainly granodiorite. Metamorphic rock fragments are less conspicuous than the intrusive fragments, are finegrained, and have a tan-orange color. It is possible they are clasts from the Belt Supergroup. The flow-breccia member is more resistant than the lower member and forms rugged outcrops. Although the outcrops appear massive, flowlayering is locally evident by crude alignment of lithic fragments or rare gas cavities. It is common to note weathered-out horizons that recede back into the outcrops. These horizons may represent flow contacts which, if correct, may indicate that the individual flows ranged from 3 feet to 30 feet thick. No sedimentation or oxidation has been noted along these contacts. No conclusive evidence regarding the origin of the Potato Hill volcanic rocks has been noted. The unconformable relation between the upper and lower members suggests that the two members may not be related to the same eruptive phase. Bitten (1951) suggested that the Potato Hill flows were caused by relatively quiet eruptions from one or more fissures in the Potato Hill vicinity. The lack of interbeds and oxidized flow contacts would suggest that the flows were probably erupted in rapid succession.

The fact that the upper member dips to the west at Potato Hill and the east at Cherry Butte makes it tempting to agree with Bitten (1951) that the area is a vent. However, the eastward dipping rocks that make up Cherry Butte can be explained by the presence of a northwest-trending fault located in the Brush Creek drainage, which may be why the lower member is present 500 feet higher on the Cherry Butte side. A vent origin is also disputed by the absence of pyroclastic features and by the nature of the lithic fragments in the flow-breccia. The rounded fragments and weakly fractured nature of the clasts in the flow-breccia suggest that they were passively incorporated into the flow. If Potato Hill was a vent, pyroclastic features and more angular and fractured clasts should be present. Until additional work is done on the Potato Hill rocks, the conclusion is they represent two stages of post-Idaho Batholith and pre-Columbia River Basalt eruptions that accumulated more than 1000 feet of rhyolite, dacite, and rhyodacite volcanism, and the upper member (second stage) may represent numerous closely spaced events. COLUMBIA RIVER BASALT GROUP Background Information The Columbia River Basalt Group erupted from fissures during an 11million year period of the Miocene (6 million to 17 million years ago). The bulk of the basalt was erupted in the first 1.5 million years (Baski, 1989) over a 163,700 km2 area (Tolan and others, 1989) that included most of eastern Washington, much of northern Oregon, and significant parts of west-central Idaho. The accessibility of the Columbia River basalt in this broad area makes it amenable to detailed stratigraphic, chemical, magnetic, and petrographic studies. Most flows of the Columbia River Basalt Group may be identified by their chemical composition. New techniques of rapid chemical analysis and magnetic polarity, in conjunction with field mapping, have enabled scientists to establish a detailed stratigraphic succession for the Columbia River Basalt Group. Based on the stratigraphy, it has been possible to clarify the physical and chemical evolution of the basalt magma, to correlate individual flows with their feeder dikes, and to reconstruct the magnitude of the eruptions.

The maximum exposed thickness of the Columbia River Basalt Group is 1,500 meters, but basaltic rocks have been reported from drill cores as deep as 3,000 meters near the center of the plateau (Hooper, 1982). The total thickness of the basalt, based on estimates of the greatest known thickness for each formation, is more than 2,500 meters. The Columbia River Basalt Group fills a shallow basin; it is thickest at the center (Pasco Basin) and thins toward the margin. The number of flows identified on the plateau is between 120 and 150 (Hooper, 1982). Individual flows are as much as 122 meters thick and average 15 to 30 meters thick. Their areal extent ranges from small spatter cones at source vents to major flows that cover a significant part of the Columbia Plateau with volumes as large as 700 cubic kilometers. The flows were erupted from north-northwest to south-southeast fissures concentrated in the southeastern part of the plateau where dikes cut through older lava flows and the surrounding pre-basaltic rocks (Swanson and others, 1975). From the base upward, the Columbia River Basalt Group in the MoscowPullman-Lewiston area is subdivided into the Imnaha, Grande Ronde, Wanapum, and Saddle Mountains Formations. Near Moscow, Idaho most basalt outcrops are the Priest Rapids Member of the Wanapum Formation. The contact between the Wanapum and underlying Grande Ronde Formation has been mapped along Paradise Creek west of Pullman (Hooper and Webster, 1982). This contact has also been identified by Brown (1976) in a test well between Moscow and Pullman at a depth of 30 meters. All of the above mentioned formations are present in the Lewiston-Clarkston area. Dike and vent materials are visible at numerous locations in northern Idaho and southeastern Washington. Basalt flows of the Grande Ronde, Wanapum, and Saddle Mountains Formations range in thickness from less than 30 centimeters to more than 100 meters. The flows record ponding in valleys, in structurally controlled basins that developed during volcanism, and in narrow canyons eroded into older flows. The intracanyon flows are common in the Saddle Mountains Basalt. All of the flows generally show evidence of ponding based on the columnar-jointed features exhibited by basalt. Columnar joints apparently form only under static cooling conditions. Flows that cooled under static conditions contracted and developed a characteristic jointing habit, which include colonnades and entablatures.

Colonnade refers to the larger columns that make up the base of the flow. Entablatures are the smaller columns at the upper part of a flow and generally constitute approximately 20% of the thickness of the flow, but it can be all of the flow or none of it. Most entablature columns are segmented by irregular cross joints, causing the columns to easily break into smaller (fist sized) pieces. The colonnade-entablature contact may be sharp, and the change generally occurs within 1 meter. These contacts are traceable, in some areas, for several kilometers. The columns in the colonnade range from 30 centimeters to 5 meters in diameter and are 15 to 30 feet in length. Most columns are straight, but curved ones are not uncommon. Individual Flows Introduction: The Columbia River Basalt Group has been subdivided into a large number of flows, members, and formations. (Swanson and others, 1979). The term "flow" is used for individual cooling units. The term "member" is used to define a flow or group of flows that can be distinguished from all others by its unique set of physical and chemical properties. These criteria include stratigraphic position, petrographic assemblage, magnetic properties, and chemical composition. From the base upward, the Columbia River Basalt Group in the MoscowPullman-Lewiston area is subdivided into the Imnaha, Grande Ronde, Wanapum, and Saddle Mountains Formations. Brief descriptions of these formations are given on the following pages. Particular emphasis is given to the Grande Ronde and Wanapum Formations because they are the predominate formations present in Latah County. For more information regarding these formations and their associated members, see Dr. John Bush at the University of Idaho. Imnaha Basalt The flows of the Imnaha Basalt conformably underlie the Grand Ronde Basalt. Generally they are medium to coarse grained with phenocrysts of plagioclase ranging in length from 0.5 cm to 2.5 cm. Exposures are characterized by extensive weathering. Most flows have normal magnetic

polarity. Because these flows were the first to fill in the prebasalt topography, they vary widely in thickness. Grande Ronde Basalt The Grande Ronde Basalt is a thick sequence of flows that occur over much of the Columbia River Plateau. The flows are fine-grained and petrographically obscure. Individual flow thickness ranges between 1 and 50 meters and covers hundreds of square kilometers. Total thickness reaches over 1000 meters in some places. The member has been divided into four units (Hooper and others, 1985) on the basis of magnetic differences and has been dated between 15.6 m.y and 17.0 m.y. (Reidel and others, 1989). From the base upward, these units are referred to as N1, R1, N2, and R2. The Grande Ronde Basalt has a narrow range of chemical composition and relatively uniform lithology. Reidel and others (1989) used chemical compositions with paleomagnetic polarity, lithology, and stratigraphic position to subdivide the formation. They were able to split the four magnetostratigraphic units into seventeen informal units that can be mapped and recognized across the Columbia Plateau. Wanapum Formation The Wanapum Formation consists primarily of the Priest Rapids Member in Latah County. The Priest Rapids Member is a coarse-grained flow with plagioclase (predominately labradorite) and olivine phenocrysts. The member occurs as an extensive flow or as flows of relatively uniform thickness over much of the plateau but is thicker in the Lewiston basin than it is in the Moscow area (Hooper and others, 1985). Major feeder dikes occur in northern Idaho (Camp, 1981). These dikes presumably fed the flows, which moved westward into the central Columbia Plateau as sheetfloods (Swanson and others, 1980). In the eastern part of the plateau, this flow overlies a dark-brown, well-developed saprolite (clayrich decomposed rock). The flows have reversed magnetic polarity (Swanson and others, 1979). Saddle Mountains Formation The Saddle Mountains Formation consists of numerous flows and interbeds. The most common members of this formation in this area from oldest to youngest are: (a) the Wilbur Creek Member; (b) the Pomona

Member; (c) the Elephant Member; and (d) the Lower Monumental Member. These members are the predominant flows of the ancestral Snake River canyon in the Lewiston basin. Remnants of these flows extend from the top of the Lewiston grade (Swanson and others,1975) to as far west as Devils Canyon in southeastern Washington (Swanson and others, 1980). In hand sample, the basalt is dark gray, fine to medium-grained, and contains small phenocrysts or laths of plagioclase. Clinopyroxene and olivine are also visible in an opaque, glassy matrix.