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MINERALS_and_ROCKS - MINERALS Exam each mineral carefully...

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MINERALS Exam each mineral carefully, making note of the diagnostic characteristics that make identification of it possible. The numbers assigned to the minerals match the numbers assigned to the mineral specimens included with your VU lab kit. It will be necessary for you to learn the name, a diagnostic trait, and the importance of each mineral for a Mineral Exam. 1. Galena Lead sulfide (PbS). Commonly found in cubic crystals, cubic cleavage, lead grey color, metallic luster, grey streak, hardness 2.5, high specific gravity (7.4-7.6), ore of lead. 2. SPHALERITE Zinc sulfide (ZnS). Dodecahedral cleavage, yellowish brown to brown color, typically resinous luster, typically yellow streak, hardness 3.5-4, specific gravity 3.9-4.1, powder treated with warm hydrochloric acid produces rotten egg smell, is the ore of zinc. 3. MAGNETITIE An oxide of iron (Fe 3 O 4 ). Magnetic, back color, metallic luster, black streak, hardness 6, specific gravity 5.18, is an ore of iron. 4. HEMATITE Iron III oxide (Fe 2 O 3 ). Granular form dark grey to black in color, earthy forms rust red, granular metallic luster, earthy varieties dull luster, reddish streak, hardness 5.5-6.5, specific gravity 5.26, most important ore of iron. 5. BAUXITE Mixture of aluminum hydroxides. Dull to earthy luster, hardness 1-3, typically pisolitic (round pea-sized grains), may be claylike, specifi c gravity 2-2.55, ore of aluminum. 6. PYRITE Iron sulfide (FeS 2 ). Bright yellow color, metallic luster, greenish black streak, commonly in cubic crystals, hardness 6-6.5, specific gravity 5.02, ore of iron and source of sulfur for making sulfuric acid. Called “Fools Gold” because of its color and luster. 7. CALCITE Calcium carbonate (CaCO 3 ). Usually white to colorless, rhombic cleavage, vitreous to earthy luster, crystals transparent to translucent, may show double refraction (Iceland Spar), hardness 3, specific gravity 2.72, reacts strongly to hydrochloric acid, source of lime for use in soil treatment and manufacture of cement and mortar. 8. DOLOMITE Calcium magnesium carbonate (Ca Mg[CO 3 ] 2 ). Usually pinkish but may be white, brown, or other colors, hardness 3.5-4, specific gravity 2.85, less vigorous reaction with
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hydrochloric acid, vitreous to pearly luster, source of lime for soil treatment. 9. FLUORITE Calcium Fluoride (CaF 2 ). Vitreous luster, octahedral cleavage, often in cubic crystals, hardness 4, specific gravity 3.18, transparent to translucent, variable colors, used as a flux and as a source of fluoride for oral hygiene and the production of hydrofluoric acid. 10. HALITE Sodium chloride (NaCl). White or colorless, cubic cleavage, vitreous luster, transparent to translucent, salty taste, hardness 2.5, specific gravity 2.16, used for table salt and source of chlorine for chemicals. 11. GYPSUM (SELENITE ) Hydrous calcium sulfate (CaSO 4 2H 2 O). Usually white or colorless, vitreous luster, transparent to translucent, tabular crystal form, soft with hardness of 2, specific gravity 2.32, three unequal cleavages, may show fibrous fracture, used in dry wall and plaster, used for fertilizer.
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