1. Minerals
Mr. Cloud
Earth Science

2. What is a Mineral? Solid Distinct elemental composition
Characteristic crystal structure

3. What is a Mineral? Example: Diamond solid
elemental composition - carbon
crystal structure - network of bonded carbon atoms - every carbon atom is connected to four others by strong atomic bonds.

4. Diamond crystal

8. Properties of Minerals
Luster
Hardness
Cleavage/Fracture
Color
Distinguishing Characteristics (Streak, Smell, Feel)

9. Luster Appearance of Mineral in Reflected Light
Metallic Luster - reflects light as a piece of tin foil or other metal would.
Nonmetallic Luster - reflects light as a piece of clay would. (no shine or reflection)

10. Metallic Luster

11. Nonmetallic Luster

12. Hardness Resistance of a mineral to being scratched Hard Med. Soft
Mohs Scale:
10 Diamond
9 Corundum
8 Topaz
7 Quartz
6 K Feldspar
5 Apatite
4 Fluorite
3 Calcite
2 Gypsum
1 Talc
Practical Scale
6.0 - nail / knife (hard steel)
5.5 - window glass
2.5 - fingernail
Hard
Med.
Soft

13. Hardness Scratched by Fingernail < 2.5
Scratched by a copper penny <3.5
Scratched by an Iron nail <4.5
Scratches glass plate > 5.5
Example#1: Your unknown sample is not scratched by the iron nail, but cannot scratch glass.
Answer: (harder than 4.5, but lower than 5.5)
Example#2: Your unknown sample is scratched by an iron nail, but not scratched by the penny.
Answer: (harder than 3.5, lower than 4.5)

14. Cleavage Tendency to break along preferred planes
One direction - splits into flat sheets
Two directions - elongate blocks
Three directions - cubes or rhombs
Four directions - diamond shapes
Six directions - “soccer balls”

15. Fracture
Fracture - the absence of cleavage

16. Cleavage

17. 2 3 1 3
Cubic cleavage
(3 directions)

18. Color
The Visual color of a mineral.

19. Distinguishing Characteristics
Streak – the color trail that a mineral leaves when it is scraped against a piece of tile.
Color – the visual color of a mineral

20. Distinguishing Characteristics
Smell – the odor that a mineral gives off.
Feel – the way a mineral feels when rubbed by the hand

21. Mineral Composition Minerals are composed of 2 or more elements.
There are 87 naturally occurring elements on Earth
There are over 4000 different minerals on the Earth

22. Periodic Table of Elements

23. Elements and Minerals
There are 10 elements that make up 99% of the Earth’s Crust.
Oxygen and Silicon make up over 70% of this by mass and over 95% by volume.
Minerals that have silicon and oxygen in their composition are called silicates.