1. Physical Properties of Minerals
In addition to the “characteristics” of minerals which are required for a substance to be a mineral, there are “physical properties” that help us determine which mineral is which.
(Review: What are the fives characteristics of minerals?)

2. 1. Hardness How easily the surface of a mineral can be scratched
Harder minerals can scratch softer ones
Can use Moh’s Hardness Scale (1 to 10)
1 = talc
10 = diamond

3. 2. Color, Transparency, Luster
Color cannot positively identify a mineral. The same mineral may have many different colors
Both of these are the
mineral flourite

4. Transparency Transparent: when you can see clearly through it
Translucent: light comes through it but you cannot see clearly through it
Opaque: no light comes through

5. Luster: how a mineral looks or reflects light
Examples: glassy, metallic, pearly, waxy, earthy

6. 3. Streak
Many minerals will leave a colored powder when they are rubbed against an unglazed ceramic tile (streak plate) – called the streak

7. 4. Cleavage and Fracture
Cleavage: if a mineral breaks or splits apart with smooth surfaces in certain directions
Fracture: if a mineral breaks with a rough or jagged surface

8. 5. Specific Gravity
Each mineral has a unique specific gravity which is a measure of density

9. Other Properties Reaction to HCl
Double Refraction – makes double image
Magnetism
Angle between crystal faces

10. Some minerals are ORES
A mineral is an ore if it contains a useful substance that can be mined at a profit.
For example, hematite contains iron
Bauxite contains aluminum (used in our foils, etc.)
YouTube video on the history of aluminum mining:

11. Gems
Gems are valuable minerals prized for rarity and beauty
Examples?