Chapter 5

Mineral Identification

Physical Properties

Properties that can be measured.

Ex) color, texture, shape, density

Physical Properties of a MineralHardness

A measure of how easily a mineral can be scratched

Soft mineral: Talc

Hard mineral: Diamond

Moh’s Scale of Hardness

Luster

• The way a mineral reflects light

• Can be metallic or non-metallic

Streak

• The color of a mineral in powdered form

• The mineral is rubbed across an unglazed porcelain tile (streak plate)

• Only works for minerals that are softer than the streak plate

Cleavage

Minerals that break along smooth flat surfaces

Fracture

Minerals that break along uneven, rough or jagged edges

ColorGood starting indicator but not good when used by itself

Other Properties

• Some minerals have special properties

• Magnetite-

attracted to magnets

• Calcite-

produces a double image

fizzes when HCl is applied

Other Properties• Fluorescence

– Glow when viewed under ultraviolet light– Examples: fluorite, calcite

• Phosphorescence– Will continue to glow even after the ultraviolet

light is removed– Examples: sphalerite, Willemite

Other Properties• Radiation

– Give off subatomic particles that can be detected by a Geiger counter

– Exposure is dangerous to living organisms– Examples: carnotite, uraninite