1. Earth Minerals

2. Minerals
Crystalline solid
Pure substance
Found in nature
Inorganic

3. Rocks
Solid aggregate of minerals (mixtures)

4. Physical Properties Color Luster Cleavage Hardness Streak Crystal Form
Specific Gravity
Special Properties

5. Color Most obvious characteristic of minerals
Most unreliable characteristic for identifying minerals
Impurities cause color variations
Example: Quartz

6. Luster
Appearance or quality of light reflected from the surface of the mineral
Descriptions:
Metallic – look like metal regardless of color

7. Cleavage A minerals tendency to break along flat surfaces
Depends on the type of bond used during the formation of mineral
Fracture – minerals that break unevenly into curved or irregular pieces
How to test: break the mineral

10. Hardness Measure of minerals ability to resist scratching
Does not mean resistance to cleavage or fracture
Hardest mineral – diamond
Hardest common mineral – quartz
Softest common mineral - talc
How to test – rub mineral along a glass slide to see if it scratches the glass or not

13. Streak Color of a mineral in its powdered form
More reliable indication of mineral color
How to test: rub mineral against streak plate

14. Crystal Form
External expression of a mineral’s internal orderly arrangement of atoms
How crystals will grow without interference

16. Specific Gravity How dense a mineral is compared to water
Minerals denser than water have a density greater than 1
Quartz, feldspar, calcite, and talc – 3 specific gravity
Hematite and magnetite – 5 specific gravity
Gold – specific gravity – 19.3 when pure
Minerals less dense than water have a density below 1

17. Specific gravity… weight of sample in air loss of weight in water

18. Special Properties Magnetic – Magnetite – most common magnetic mineral
Lodestone – type of magnetite that acts like a magnet

19. Fizzes with acid:
Calcite will fizz when hydrochloric acid is placed on the sample
The fizz produces carbon dioxide gas CO2

20. Taste: Mineral will have a particular taste like salt
How do you test – lick it

21. Fluorescence
Minerals absorb ultraviolet light and then produce visible light of various colors
Calcite appears white but under UV light appears red

22. Odor – Minerals that smell Sphalerite – rich in zinc
How to test – scratch the mineral and smell

23. Double Refraction –
Light rays that bend as they pass through the mineral
When the light bends it splits into 2 rays and produces a double image

24. Mineral ID practice…
What is…? 1. 2. 3.

25. How Crystalline Minerals Form
Evaporation of solutions
Halite and Gypsum
Cooling of melted substances
Quartz and Olivine