1-2 Identifying Minerals

1. Classify Minerals using common mineral identification

techniques.

2. Explain special properties of minerals.

Color

• Color is not the best factor to use in identifying a mineral.

• Impurities and weathering cause minerals to come in different colors.

Luster – The way lights reflects off a mineral’s surface.

• Metallic – shiny like metal

• Sub-metallic – shiny but not smooth looking.

• Non-metallic – vitreous, silky, resinous, waxy, pearly, and earthy.

Streak – the color of a mineral in powdered form.

• Rub a mineral against an unglazed porcelain tile (streak plate)

• Streak color is a more reliable way to use color in identifying a mineral in some cases.

Cleavage Vs Fracture

• Cleavage is the tendency for some minerals to break along flat surfaces.

• Fracture is the tendency for some minerals to break unevenly along curved or irregular surfaces.

Hardness – a mineral’s resistance to being scratched.

• Use Moh’s hardness scale where 1 is softest and 10 is hardest.

Density – The measure of how much matter there is in a given amount of space.

• D = m/v• Water is 1g/cm3

• Specific gravity – the ratio of a mineral’s density to water’s

• Gold is 19

Special Properties

• Fluorescence – minerals glow under a black light.

• Chemical Reaction – reacts with acid

• Optical properties – when looking through a mineral the appearance changes

• Taste – mineral has a distinctive taste.

• Magnetism – mineral will attract iron objects.

• Radioactivity – minerals that contain uranium or radium can be detected with a Geiger counter