Mineral Identification

Color

• Most notable characteristic

• Caused by presence of trace elements or compounds

• Least reliable way to identify a mineral because:– Different mineral can have same color– Same mineral can have different color

Luster

• the way a mineral reflects light

• can be either metallic or non metallic

• if non metallic it can be dull, pearly, waxy or silky.

Streak

• the color of the powder left behind when a mineral is rubbed on a streak plate.

• Does not always match the minerals color

• Minerals streak stays constant, even if weathered.

Hardness

• the measure of how easily a mineral can be scratched

• one of the most useful ways of identifying a mineral

• use Moh’s scale of hardness

Cleavage

• a mineral that breaks relatively easily, along even planes is considered to have cleavage

Fracture

• minerals that break with rough or jagged edges have fracture

http://academic.brooklyn.cuny.edu/geology/grocha/mineral/cleavage.html

Special properties

• Calcite – double refraction & fizzes w/ HCl

• Magnetite – magnetic

• Sulfur – smells like rotten eggs

• Halite – salty taste