Minerals & Rocks

Minerals Naturally occurring, homogeneous substances that are inorganic. Minerals make up rocks Feldspar Quartz

Mineral Characteristics Color Luster Hardness Streak Cleavage Crystal structure Density

Color Not a great identifying characteristic Many minerals are the same color Some minerals come in many colors

Luster The way light is reflected off the surface Metallic Luster Hard, shiny look, like metal Nonmetallic Luster Can still be shiny, but some light passes through

Hardness Ability to scratch other minerals Mohs’ Scale of Hardness

Streak The powdered form of the mineral Found by rubbing the mineral on an unglazed streak plate

Cleavage Tendency of a mineral to break along flat planes

Crystal Structure Many minerals have distinctive crystal shapes

Density Specific Gravity Ratio of the density of a substance to the density of water If density = 4 g/ml Specific gravity = 4