1. Minerals Notes

2. Minerals: naturally occurring, inorganic solids, with definite structure and composition; made of one or more elements
Characteristics of Minerals:
Formed by natural processes
Inorganic (not formed from life processes)
Solid
Definite chemical composition, can have minor variations (example: salt is NaCl)
Atoms arranged in a pattern

3. Structure of Minerals: minerals are in the form of crystals (a solid in which the atoms are arranged in repeating patterns)
Crystal Systems: Examples of Perfect Crystal Systems
Cubic Tetragonal Hexagonal
Examples: Isometric - Cubic-Halite (salt); Platinum
Tetragonal - Zircon; Wulfenite
Hexagonal - Quartz; Corundum

4. CRYSTAL SYSTEMS are divided into 6 main groups
CRYSTAL SYSTEMS are divided into 6 main groups. We will look at 3 groups.
The first group is the ISOMETRIC. This literally means “equal measure” and refers to the equal size of the crystal axes.
Examples:
·Gold
·Copper
·Diamond
· Lazurite
·Galena
· Pyrite

5. HEXAGONAL CRYSTALS a HEXAGONAL Crystal Axes
Three horizontal axes meeting
at angles of 120o and
one perpendicular axis.
Examples:
·Graphite
·Nickeline
·Molibdenite
·Apatite
·Vanadinite
· Beryl
These hexagonal CALCITE crystals nicely show the six sided prisms

6. Hexagonal Crystals

7. TETRAGONAL CRYSTALS TETRAGONAL
Two equal, horizontal, mutually perpendicular axes
Vertical axis is perpendicular to the horizontal axes and is of a different length.
Examples:
· Tourmaline
·Dolomite
·Hematite
·Corundum
· Idocrase
Hematite
Green Tourmaline

8. TETRAGONAL CRYSTALS
WULFENITE
Same crystal seen edge on.

9. How Minerals Form:
1. Form from the cooling of hot melted rock (magma); If it cools fast, crystals tend to be small; cools slow, larger crystals tend to form
2. Form from solutions-as liquid evaporates, minerals solidify and form crystals

10. Major Mineral Groups:
Silicates-Made of Silicon, Oxygen, & possibly other element(s); largest group of minerals
Example: Quartz
(SiO2)
Carbonates-Made of Carbon, Oxygen, & possibly other elements
Examples: Calcite (CaCO3); Magnetite (MgCO3)
Pink Quartz
Calcite samples

11. Most Abundant Elements in Earth’s Crust:
1. Oxygen 46.6%
2. Silicon 27.7%
3. Aluminum 8.1%
4. Iron 5%
5. Calcium 3.6%
6. Sodium 2.8%
7. Potassium 2.6%
8. Magnesium 2.1%
***All other elements make up 1.5% of the Earth’s crust.

12. Physical Properties of Minerals:
Hardness-a measure of how easily a mineral can be scratched
***1 is the softest, 10 is the hardest***
Moh’s Scale of Hardness
Sample Element
Hardness
Common Objects
Talc 1
Fingernail (2.5)
Copper penny (3.5)
Iron Nail (4.5)
Glass (5.5)
Steel File (6.5)
Streak Plate (7)
Gypsum 2
Calcite 3
Fluorite 4
Apatite 5
Feldspar 6
Quartz 7
Topaz 8
Corundum 9
Diamond 10
Apatite
Gypsum

13. Luster Describes how light is reflected from a mineral’s surface
Metallic
Nonmetallic
dull; pearly; silky; glassy; brilliant; transparent
Waxy
Resinous (looks like freshly broken shellac)

14. Color
The color seen when looking at the surface of the mineral; Least reliable property because many minerals can be many colors
Example: Sulfur is pale yellow

15. Streak
The color of the mineral when it’s broken up in powdered form; Use a porcelain tile to test; Useful for softer minerals; Minerals with a hardness greater than 7 do not leave a streak
Example: Gold has a gray streak

16. The Way a Mineral Breaks
Cleavage-When a mineral breaks along smooth, flat surfaces; Example: Mica
Fracture-When minerals break with rough or jagged edges; Example: Quartz

18. Special Properties
Unusual or unique qualities; Examples: Magnetite is magnetic, Calcite has optical qualities, Jade has a bell-like ring when tapped, Halite has a salty taste, and Sulfur smells like rotten eggs

19. Uses of Minerals:
Gems - Highly prized minerals because they are rare and considered beautiful; the difference in a gem and the common form of a mineral can be slight

20. Month
Birthstone
January
Garnet
February
Amethyst
March
Aquamarine
April
Diamond
May
Emerald
June
Pearl
July
Ruby
August
Peridot
September
Sapphire
October
Opal
November
Topaz
December
Turquoise

21. Ores - contain useful substances that can be mined for a profit
Examples: Bauxite contains Aluminum
Hematite contains Iron
Sphalerite contains Zinc
Chalcopyrite contains copper

23. Strip Mining - removing ore by digging at Earth’s surface; usually results in a huge pit
Land Reclamation - mining companies are required to return soil and rock to open pit and cover it with topsoil then plant trees and grass

24. Asbestos - a mineral with threadlike, flexible fibers used as insulation and as fire protection; has been shown to cause lung diseases including lung cancer
EPA (Environmental Protection Agency) -requires school officials to inspect buildings every six months; flaking asbestos must be removed or sealed over

25. Minerals can contain other useful elements:
1. Elements must be refined, or purified, from ores
2. Some elements dissolve in fluids, travel through weaknesses in rocks, and in those weaknesses form mineral deposits called vein mineral deposits
3. Titanium is useful element derived from the minerals limonite and rutile