MINERAL IDENTIFICATION

Minerals have Physical Properties based on the INTERNAL ARRANGEMENT OF ATOMS & CHEMICAL COMPOSITION

Most Minerals can be identified by inspection and or by simple tests.

Mineral Identification Tests Color Hardness Streak Luster Density Specific Gravity and Known Unique Properties

Color for some minerals color is directly related to the composition Color is the least diagnostic property

Luster appearance of a mineral in reflected light A mineral that shines like a metal has metallic luster A mineral that transmits the light has a nonmetallic luster

Texture How a mineral feels to the touch. Examples: smooth, greasy, silky, ragged, rough, soapy, and glassy

Streak Color of finely powdered mineral. The streak color and mineral color are not always identical. The streak color is typically constant for a given mineral.

Hardness how easily a mineral can be scratched measured using Mohs hardness scale (what can scratch what)

Reference Materials --fingernail at old penny (copper) at window glass or typical knife blade porcelain plate or good steel file 7.5

Absolute Hardness 1 Talc 72 Orthoclase 3 Gypsum 100 Quartz 9 Calcite 200 Topaz 21 Fluorite 400 Corundum 48 Apatite 1600 Diamond Absolute HardnessTalcOrthoclaseGypsumQuartzCalciteTopazFluoriteCorundumApatiteDiamond

Cleavage and Fracture Internal Arrangement of Atoms determines how a mineral will break

Cleavage - repeatable breaks along definite plane surfaces, At least one Flat Side Fracture - uneven non repeated breaks, All rough Sides

Density Minerals have a constant density Impurities in your sample may cause the density to vary slightly

Specific Gravity Weight air  (Weight air - Weight water )

Known Unique Properties Examples Acid Test Refraction/Reflection of Light Magnetic Properties

Acid Test Calcite (CaCo 3 ) bubbles (reacts) when dilute hydrochloric acid (HCL) is dropped on its surface