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Published byThomas Pitts Modified over 8 years ago
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Composition and Structure of Minerals
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It occurs naturally It is a solid It has a definite chemical composition Its atoms are arranged in an orderly pattern (specific crystal shape) It is inorganic (it was never alive)
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~4000 known minerals Examples: quartz, gold, halite and diamond Most minerals are compounds Quartz: compound of Silicon and oxygen
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Regular geometric shape with smooth surfaces (the crystal faces) All minerals have crystalline structures. Only 6 basic types of crystal shapes
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Reflectance of light off surface of a mineral Either metallic luster or non-metallic categories NM subcategories: pearly, earthy, greasy, or glassy appearances. Metallic Minerals Non-metallic Minerals
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Crystal structure determines how mineral cleaves (breaks); splits along weak bonds; based on number of PARALLEL planes Fracture: irregular pattern of breakage in directions other than along cleavage planes
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Resistance of a mineral to scratching. In class, we will do a greater than or less than comparison. If the mineral is not scratched by a penny and does not scratch glass, then 3< mineral < 5.5. Talc can be scratched with a fingernail, so we would say the hardness is <2.5
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Property of mineral that describes its color in powdered form. TEST: Use a streak plate (tile) to determine the mineral’s streak.
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Easy to see Does NOT distinguish one mineral from another NOT a defining test to determine a mineral.
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Some minerals react when placed within a magnetic field. Some strongly attracted to the magnet, some weakly attracted, and one mineral is actually repelled.
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All carbonate minerals fizz when weak hydrochloric acid is applied to them.
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Comparison of weight of mineral in air with weight suspended in water Density = mass/volume
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Luster Cleavage Streak Hardness Color Specific Gravity Magnetism Acid Test Video Video Video cleavage and hardness start at min 1:22cleavage and hardness
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