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DEFINITION OF MINERAL Naturally occurring, Inorganic Solid with a definable chemical composition and crystal structure Physical Properties Crystal Form (Shape). Cubic - Fluorite. Dodecahedron - Garnet. Hexagonal Prism - Quartz. Octahedron - Magnetite. Cleavage Page 22.
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DEFINITION OF MINERAL Naturally occurring, Inorganic Solid with a definable chemical composition and crystal structure Physical Properties Crystal Form (Shape)
Cleavage Page 22 Tendency to break along planes of weaker atomic bonds. Cleavage produces flat, shiny surfaces. Described by the number of planes and their angles.
Examples of cleavage • One direction • Two directions at 90º • Two directions NOT at 90º Muscovite mica Potassium Feldspar Amphibole
Calcite • Examples of cleavage • Three directions at 90º • Three directions NOT at 90º
Fracture • Minerals break in ways that reflect atomic bonding. • Fracturing implies equal bond strength in all directions. • Example: quartz displays conchoidal fracture. • Shaped like the inside of a clam shell. • Breaks along smooth curved surfaces.
Specific Gravity The weight of a mineral compared to the same volume of water LusterPage 23 Intensity of light reflected off a mineral Metallic, non-metallic- glassy (vitreous) and earthy (dull) Color and Streak
Hardness • Scratching resistance of a mineral. • Derives from the strength of atomic bonds. • Hardness compared to the Mohs scale for hardness. • Talc, graphite • Gypsum • Calcite • Fluorite • Apatite • Orthoclase • Quartz • Topaz • Corundum • Diamond Soft - Scratched by Fingernail Medium - Does not scratch glass, not scratched by Fingernail Hard- Scratches Glass
Other Properties Reaction with acid Taste Magnetism