1. Chapter 5.2 – 5.4 Minerals
Earth Science 1

2. Minerals Mineral – A mineral is any material that… 1. Is a Solid
2. Is Inorganic
3. Is Naturally Occurring
4. Has a Fixed Chemical Composition
5. Atoms Are Arranged in Orderly Pattern 2

3. Minerals and How They Form

4. Critical Thinking #1 Is water a mineral? Why or why not?
Is a seashell a mineral? Why or why not?
Is plastic a mineral? Why or why not? 4

5. Minerals
Crystal Form
Many minerals possess a crystalline form – regular geometric shapes with smooth faces 5

6. Crystal Structures

7. Two Types of Minerals Silicates Contains Silicon (Si) and Oxygen (O)
90% of Earth’s Crust 7

8. Two Types of Minerals Non-Silicates
No Combination of Silicon (Si) and Oxygen (O)
Common Non-Silicates
Carbonates (Carbon + Oxygen)
Oxides (Iron or Aluminum + Oxygen)
Sulfates (Sulfur + Oxygen) 8

9. Identifying Minerals Color
Easily observed, but… the same minerals can vary in color
ex: Sulfur = Yellow
Quartz = Clear, Purple,
Green, Red etc. 9

10. Colors of Quartz
Clear Quartz Amethyst Rose Quartz

11. Critical Thinking #2
Is color a good way to identify minerals? Why or why not? 11

12. Identifying Minerals Streak The color of a mineral in powdered form
More reliable than color 12

13. Identifying Minerals Luster How a mineral reflects light
Metallic – reflective, silver or gold color, found in most metals 13

14. Identifying Minerals Nonmetallic Luster – not reflective
Vitreous – glassy
Silky – fibrous
Resinous – yellow, dark brown
Waxy
Pearly
Earthy – dull, looks like clay 14

15. Identifying Minerals Cleavage Fracture (No Cleavage)
Minerals break along a smooth, flat surface
Fracture (No Cleavage)
Minerals break unevenly along an irregular surface 15

16. Critical Thinking #3
From your experience, do most minerals fracture or demonstrate some type of cleavage? Explain your reasoning. 16

17. Identifying Minerals Hardness Mohs Scale – (1-10) Softest to Hardest
1- Talc (Softest)
10 – Diamond (Hardest) 17

18. Identifying Minerals
Two More Methods
Malleability: How well the mineral can be hammered into shape.
Ductility: How well the material can be drawn out into a thin wire without crumbling.
10/25/13

19. Critical Thinking #4
Based on the hardness scale, how would the scale need to be adjusted if a new mineral was discovered that was harder than a diamond? 19

20. Identifying Minerals Special Properties
Fluorescence – glow under ultraviolet radiation
Chemical Reactions – fizz when combined with acid
Optical Properties – double image formed
Magnetism – ex: Magnetite is magnetic
Taste ex: Halite (salt) tastes salty
Radioactivity – contains radium or uranium 20

21. Critical Thinking #5
Which special properties tests would be difficult to conduct? Which would be easy? 21

22. Major Silicates: Quartz
Glassy or greasy luster
Colorless or white (some variations)
Conchoidal or irregular fracture
Mohs scale 7
Found in granite and other rocks

23. Feldspars Two directions of cleavage Hardness scale 6 Pearly luster
Contains aluminum
plagioclase
orthoclase

24. Other Silicates
amphibole
pyroxene
mica
olivine

25. Carbonates
limestone
marble
calcite

26. Oxides and Sulfides
magnetite
hematite
Pyrite
(fool's gold)

27. Archimedes Principle
If an object can displace the volume of water equal to the weight of the object, it will float.