DEFINITION OF MINERALNaturally occurring, Inorganic Solid with adefinable chemical composition and crystal structurePhysical Properties

Crystal Form (Shape)

Cubic - Fluorite

Dodecahedron - Garnet

Hexagonal Prism - Quartz

Octahedron - Magnetite

Cleavage Page 22Tendency to break along planes of weaker atomic Tendency to break along planes of weaker atomic bonds. bonds.

Cleavage produces flat, shiny surfaces.Cleavage produces flat, shiny surfaces.

Described by the number of planes and their angles.Described by the number of planes and their angles.

Potassium FeldsparPotassium Feldspar

Muscovite micaMuscovite mica

AmphiboleAmphibole

• Examples of cleavage

– One direction

– Two directions at 90º

– Two directions NOT at 90º

CalciteCalcite

Examples of cleavageThree 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

Luster Page 23 Intensity of light reflected off a mineral Metallic, non-metallic- glassy (vitreous) and earthy (dull)

Color and Streak

Scratching resistance of a mineral.Derives from the strength of atomic bonds. Hardness compared to the Mohs scale for

hardness.1. Talc, graphite2. Gypsum3. Calcite4. Fluorite5. Apatite6. Orthoclase 7. Quartz8. Topaz9. Corundum10. Diamond

Hard- Scratches Glass

Soft - Scratched by Fingernail

Medium - Does not scratch glass, not scratched by Fingernail

Hardness

Other PropertiesReaction with acidTasteMagnetism