Minerals & Rocks

Mineral

A naturally occurring, solid, and inorganic substance that has definite chemical composition and molecular structure (elements make up minerals)

Mineral Characteristics

Based on physical or chemical properties

Ore

A mineral from which a metal can be extracted

Mineral Characteristic: Color

The most visible but very unreliable

Mineral Characteristic: Streak

The colored powder form of the mineral that remains after being scratched on an unglazed porcelain plate; can be a different color than the surface color but is a reliable test for identification

Mineral Characteristic: Luster

The way in which the light is reflected off the surface of the mineral

Metallic Luster

Shines like metals (silver, gold)

Nonmetallic Luster

Vitreous (glass like appearance), resinous, pearly, greasy, glossy, dull, earthy

Mineral Characteristic: Hardness

The mineral’s ability to resist being scratched

How is the relative hardness of a mineral determined?

By comparing it to the hardness of the ten minerals on the Moh’s Scale of Hardness and to the hardness of glass at 5.5

Mineral Characteristic: Cleavage

The tendency of a mineral to split along smooth, flat surfaces