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
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