Physical Geology Laboratory Tuesday Tom Burbine

Mineral A naturally occurring, homogeneous inorganic solid substance having a definite chemical composition and characteristic crystal structure 4,000 known minerals –Of these, perhaps 100 can be called "common", –50 are "occasional“ –rest are "rare" to "extremely rare".

Is ice a mineral?

Yes, as long as it was made inorganically

Crystal Structure Crystalline structure - orderly three-dimensional arrangement of atoms or molecules Forms crystals

Color Usually the most noticeable property Sometimes minerals can have a wide variety of colors

Clarity Transparent – clear Translucent – foggy Opaque – light doesn’t travel through

Crystal Form Perfectly grown crystals can have a perfect crystal form (e.g., cube, pyramid, prism)

Luster How light reflects from a mineral Metallic luster – reflects like a metal Nonmetallic luster – doesn’t reflect like a mineral –Vitreous – like a glossy photograph –Waxy – like the luster of a candle –Satiny – like the luster of satin –Earthy – like dry soil –Greasy – like the luster of grease –Porcelaneous – like the luster of porcelain

Streak Color of a substance as a fine powder A mineral is scratched on a streak plate

Hardness Mohs Hardness scale 1-10 scale Hard minerals- can scratch glass Soft minerals – –can’t scratch glass

Cleavage Cleavage – tendency of some minerals to break along flat, parallel surfaces Cleavage planes are parallel surfaces of weak chemical bonding Fracture is a break in a mineral does not occur along a cleavage plane

Tenacity Tenacity - resists breakage Brittle – shatters like glass Malleable – like clay Elastic – like a plastic comb Sectile – carved with a knife

Reaction with acid Fizzes with cool, dilute hydrochloric acid Carbonate minerals (minerals with CO 3 ) Calcite readily fizzes Dolomite will only fizz if powdered

Striations Straight, hairline grooves on the cleavage surfaces Plagioclase feldspar has striations

Magnetism Magnetic Magnetite is magnetic

Specific gravity Density of a substance divided by the density of water E.g., quartz has a specific gravity of 2.65

Any Questions?