Properties of Minerals

Hardness - resistance to being scratched Mohs Hardness Scale Mohs Hardness Scale ranges from 1(talc) to 10 (diamond) ranges from 1(talc) to 10 (diamond) a mineral will only scratch those softer than it a mineral will only scratch those softer than it Field scale Field scale common test using fingernail (1), penny (3), glass (6) common test using fingernail (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 surface glassymetallic submetallicnonmetallic

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 mines Back to the salt mines Sitting on a gold mine Sitting on a gold mine the need to return to work or some activity that is not fun in control of something valuable