1. Aim: How do we identify minerals?

2. Learning Objective
Students will describe the properties that can be used to identify minerals.

3. Do Now

4. Key Terms
Physical property
Streak
Luster
Hardness
Cleavage
Fracture

5. Physical Properties
A physical property is the observable characteristic that describes an object.
Physical properties help identify minerals.
Some physical properties of minerals are color, streak, luster, and hardness.

6. Color Color is an important property of minerals.
Color alone cannot be used to identify a mineral.
Many minerals are the same color.
For example, gold and pyrite are both brassy yellow. Pyrite is called “fools gold”.

7. Streak The color left by a mineral is called a streak.
When a mineral is rubbed across a piece of unglazed porcelain tile, a streak is left.
The streak test works only for minerals that are softer than the streak plate.

8. Is it Gold or Not?
A test to see if you have found pure gold or pyrite would be a streak test.
Gold will leave a yellow streak and pyrite will leave a greenish-black streak.
So, are those gold nuggets you have gold?
Pyrite streak

9. Luster The way a mineral’s surface reflects light is called luster.
Minerals have metallic or nonmetallic luster.
Calcite has a glassy or a dull luster.

10. Hardness
The property of a mineral to resist being scratched is called hardness.
Moh’s scale ranks ten minerals in hardness from 1 to 10.
A mineral with a high number can scratch any mineral that has a lower number.

11. Cleavage and Fracture
Cleavage is the splitting of minerals into pieces with smooth, flat surfaces; the way a mineral shows cleavage is always the same for that mineral.
Fracture is the splitting of a mineral into jagged or uneven pieces.

12. Checking Concepts What property allows one mineral to scratch another?
The color of a powdered mineral on an unglazed porcelain tile is its ________.
The softest mineral on Moh’s hardness scale is _________.

13. Answers
Hardness
Streak
Talc

14. The End