1. Minerals

2. All minerals are rocks, but not all rocks are minerals!
Minerals vs. Rocks
Rock – an aggregate of minerals (mixture of minerals).
Mineral – naturally occurring, inorganic, crystalline solids, with a definite chemical composition.
All minerals are rocks, but not all rocks are minerals!

3. Granite
(rock)
mixture of:
Feldspar
(mineral)
Quartz
(mineral)
Biotite
(mineral)

4. Properties of Minerals
1. Crystal Form
External expression of a mineral’s internal orderly arrangement of atoms.
Size of the crystal is based on time & available space.

5. Crystal Shapes: Cubic Hexagonal Tetragonal Orthorhombic Monoclinic
Triclinic

6. Properties of Minerals
2. Luster
Appearance /quality of light reflected from the surface of a mineral.
Metallic vs. Nonmetallic.

7. Choosing the Luster: Luster Shiny like a metal? Yes Metallic No
Nonmetallic
What kind of nonmetallic?
Vitreous
(glassy)
Pearly
Silky
Resinous
Earthy

8. Properties of Minerals
3. Color
Outer appearance.
Unreliable property.
A mineral may have several color varieties.

9. Properties of Minerals
4. Streak
Color of the mineral in a powdered form.
Obtained by rubbing the mineral across a streak plate.

10. Properties of Minerals
5. Hardness
Resistance to abrasion or scratching.
Mohs’ Scale
Talc
Gypsum
Calcite
Fluorite
Apatite
Feldspar
Quartz
Topaz
Corundum
Diamond
Softest
Hardest

11. How to test a mineral’s hardness
Start by moving an unknown sample across a sample with a hardness of 1.
2. If the unknown scratches the known sample, then it is harder….so keep testing the others until it doesn’t scratch it.
3. If it doesn’t scratch it, then it is softer than the known sample so it is lower on the scale.
4. If they scratch each other, they are the same hardness.

12. Properties of Minerals
6. Cleavage
Tendency for a mineral to break along planes of weak bonding.
Smooth surfaces.
Not to be confused with crystals.

13. Properties of Minerals
7. Fracture
Opposite of cleavage.
Conchoidal fracture = curved edges.
Fibrous fracture = splinters/fibers.

14. Properties of Minerals
8. Specific Gravity
Comparison between the weight of a mineral to the weight of an equal volume of water.
Comparison of densities.
Written as the number of times heavier/lighter than water.

15. Properties of Minerals
9. Other Properties
Taste
Elasticity
Malleability
Texture
Magnetism
Double Refraction
Reaction to acids (HCl)

16. Mineral Groups O Si Al Fe Ca Na K Mg
8 elements make up 98% of the Earth’s crust (by weight). O Si Al Fe Ca Na K Mg

17. Mineral Groups Silicate Group Minerals made of O and Si.
¾ of the minerals in the continental crust are silicates.
Silicon-oxygen tetrahedron (1 silicon to 4 oxygen) then bonded to another element(s).
EXAMPLES:
Quartz, Feldspars, Micas

18. Mineral Groups Carbonates Group Halides Group
Minerals made of CO3 bonded with other elements.
EXAMPLES:
Calcite & Dolomite
Halides Group
Minerals made with members of the halogen family.
Formed through evaporation.
Halite & Fluorite

19. Mineral Groups Sulfates Group Oxides Group
Minerals made of SO4 bonded with other elements.
EXAMPLES:
Gypsum
Oxides Group
Minerals made with Oxygen bonded with other elements.
Hematite & Ice

20. Mineral Groups Native Elements Group Sulfides Group
Minerals that are pure elements (usually metals).
EXAMPLES:
Copper, Diamond, Graphite
Sulfides Group
Minerals made with Sulfur bonded with other elements.
Pyrite

21. Mineral Resources
Ores – useful metallic minerals that are mined at a profit.
EXAMPLES: Hematite (Iron), Sphalerite (Zinc), Galena (Lead), Cinnabar (Mercury).
Industrial rocks & minerals – useful nonmetallic minerals that are mined at a profit.
EXAMPLES: Fluorite, Sulfur, Halite (salt)
The amount of a mineral in a deposit must be concentrated several times it’s crustal percentage to be considered profitable.

22. Mineral Resources
Gemstones – Crystal forms of minerals that posses beauty of such quality that command a price when cut & polished.
Precious gems – have beauty, durability, size, and rarity.
Diamond
Emerald (Beryl)
Ruby (Corundum)
Sapphire (Corundum)

23. Mineral Resources
Semiprecious gems – only have one or two of the qualities of precious gems.
EXAMPLES: Amethyst , Topaz, Garnet, Zircon
Non-mineral gems – stones that have value, but are not minerals.
EXAMPLES: Coral, Amber, Pearl
Precious Metals – metallic minerals that have high value.
EXAMPLES: Gold, Silver, Platinum