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DR. GORE'S HANDY DANDY GUIDE TO
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This handy dandy guide gives the most diagnostic properties of each of the common minerals we see in lab.
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Mineral |
Most Diagnostic Properties |
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Amphibole |
2 directions of cleavage not at 90° , usually dark in color, green to black, scratches glass |
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Apatite |
glassy, color variable but commonly green, softer than glass but harder than a nail. |
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Barite |
white to brown or orange, very high specific gravity or density. |
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Biotite mica |
1 direction of cleavage, black to brown |
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Calcite |
rhombohedral cleavage, fizzes in acid |
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Dolomite |
fizzes in acid only if powdered |
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Fluorite |
softer than glass, glassy, variety of colors, four directions of cleavage |
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Galena |
gray, metallic, cubic cleavage, high density |
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Graphite |
gray, marks paper and smudges fingers |
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Gypsum (Selenite) |
usually light color, softer than fingernail, fibrous, granular or rhombohedral cleavage |
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Halite |
cubic cleavage, salty taste |
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Hematite |
metallic and silvery or reddish brown; has red-brown streak |
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Kaolinite |
white, dull luster, it will stick to a moistened finger |
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Magnetite |
black or gray, magnetic |
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Muscovite mica |
1 direction of cleavage, silvery color |
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Native copper |
metallic, "copper-colored", high density, commonly in irregular nuggets |
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Native sulfur |
bright yellow color, low density |
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Olivine |
olive green, granular or glassy, no cleavage |
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Plagioclase feldspar |
white or gray, 2 directions of cleavage at 90° , scratches glass |
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Potassium feldspar (orthoclase or microcline) |
pink, white, green, 2 directions of cleavage at 90° , scratches glass |
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Pyrite |
golden or brassy color, metallic luster, irregular fracture, no cleavage but cubic crystals with striations on some faces may be present, gray streak |
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Pyroxene |
usually dark in color (green to black), 2 directions of cleavage at 90° |
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Quartz |
colorless or color variable, glassy, scratches glass, conchoidal fracture, no cleavage |
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Serpentine |
green color, no cleavage, may contain asbestos fibers. |
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Sphalerite |
brownish, pale yellow streak with sulfur odor, has cleavage |
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Talc |
Softer than fingernail, white to green, soapy feel, pearly luster |
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This page created by Dr. Pamela J. W. Gore,
Gerogia Perimeter College, Clarkston, GA
pgore@gpc.edu
Revised May 15, 1998.
Revised September 1, 1999
Revised September 12, 2003
Revised January 12, 2005