Properties of MineralsProperties of Minerals

Hardness - resistance to being scratched

Mohs Hardness ScaleMohs Hardness Scale ranges from 1(talc) to 10 ranges from 1(talc) to 10

(diamond)(diamond)

a mineral will only scratch a mineral will only scratch those softer than itthose softer than it

Field scaleField scale common test using fingernail common test using fingernail

(1), penny (3), glass (6)(1), penny (3), glass (6)

Color- not a reliable indicator of identity due to weathering and

impurities

Look at the 2 fluorite samples.

Streak – the colored powder left when rubbed against a hard surface (more reliable than color because streak is not affected by weathering)

Luster: ability to reflect light on its surfaceglassy metallicsubmetallic nonmetallic

Cleavage & Fracture: the way a mineral breaks when stressed

Cleavage: the tendency to break along flat surfaces and smooth lines (along weak bonds)

Fracture: the quality of the break; typically uneven along curved or irregular surfaces if

mineral’s atomic bonds are strong

Crystal Shape – the natural growth of a mineral

Taste: certain minerals like halite (salt) and sulfur have characteristic flavors (only water soluble minerals

do)

Specific gravity: the ratio of an object’s density to the density of water

Magnetism: Magnetite has magnetic properties

Reaction to Acid: an acid, such as hydrochloric acid (HCl), can cause a mineral to fizz

Fluorescence: Calcite and fluorite can glow under UV light.

Optical properties: Calcite can create a double image

Idioms to Ponder

Back to the salt minesBack to the salt mines

Sitting on a gold mineSitting on a gold mine

the need to return to work or some activity that is not fun

in control of something valuable