Section-2 Mineral Identification pg.68
What you’ll learn
Describe physical properties used to identify minerals.
Identify minerals using physical properties such as hardness and streak.
Cleavage and fracture
How it looks like
What color is it?
Which one of the following is gold? Identify by appearance.
A measure of how easily a mineral can be scratched
Mohs Hardness Scale
1 Softest known mineral. It flakes easily when scratched by a fingernail.
2 A fingernail can easily scratch it.
3 A fingernail cannot scratch it, but a copper penny can.
4 A steel knife can easily scratch it.
5 A steel knife can scratch it.
6 Cannot be scratched by a steel knife, but it can scratch window glass.
7 Can scratch steel and hard glass easily.
8 Can scratch quartz.
9 Can scratch topaz.
10 Hardest known mineral. Diamond can scratch all other substances.
The way a mineral reflects a light luster.
Either metallic or nonmetallic
The specific gravity of a mineral is the ration of its weight compared with the weight of an equal volume of water.
Gold has specific gravity of 19
It means gold is 19 times heavier than water.
When a mineral is rubbed across a piece of porcelain tile a streak of powdered mineral is left behind.
Cleavage is the way that mineral breaks.
Minerals that break along smooth, flat surfaces have cleavage.
Mica has cleavage