1. Minerals

2. What is a Mineral? Naturally Occurring Inorganic Solid
Definite Chemical Formula
Definite Crystal Structure

3. Naturally Occurring Formed by natural processes not in the laboratory.
Is an ice cube a mineral?
Is the ice on the windshield of a car a mineral?
Minerals manufactured by humans are not considered minerals.

4. Inorganic Formed by inorganic processes; not living
Minerals are not made from living things.
Coal is made of carbon. Is it a mineral?

5. Solid Minerals cannot be a gas or a liquid.
- H2O as ice in a glacier is a mineral, but
water is not.

6. Definite Crystal Structure
Highly ordered atomic arrangement of atoms in regular geometric patterns
Minerals are crystals with a repeated inner structure.
Apatite
Feldspar
Diamond
Quartz

8. Definite Chemical Formula
Minerals are expressed by a specific chemical formula.
Gold (Au)
Calcite (CaCO3)
Quartz (SiO2)
Pyrite (FeS2)
Minerals made of only one type of atom (element) are called native elements.
Gold
Copper
Silver

9. Types of minerals
Minerals are most commonly classified by chemical composition.
The 2 main groups are silicates and nonsilicates.

10. Silicates
Minerals containing a combination of silicon (Si) and oxygen (O) (most common elements in the earth’s crust)
Silicate minerals comprise about 90% of the Earth’s crust.
Silicates minerals often contain other elements such as aluminum, iron, magnesium, and potassium.
Granite is a rock comprised of the minerals feldspar, biotite mica and quartz.

11. Feldspar
Feldspar minerals make up half of the Earth’s crust and is the main component of most of the rocks found on the Earth’s surface.
Feldspar contains Si, O, Al, K, Na, and Ca
Feldspar

12. Biotite Mica Soft and shiny minerals that separate easily into sheets
Biotite is one variety of mica

13. Quartz
Silicon dioxide ( SiO2) is the basic building block of many rocks

14. Nonsilicates Minerals that do not contain the combination of Si and O
Some of these minerals are made up of C, O, F, and S

15. Classes of Nonsilicates
Native Elements
Carbonates
Halides
Oxides
Sulfates
Sulfides

16. Native Elements Native elements are composed of only 1 element
About 20 exist including Au, Pt, C, Cu, S and Ag

17. Carbonates
Contain the combinations of carbon and Oxygen in their chemical structure
Calcite (CaCO3 ) is an example
Carbonates are used in cement, building stones and fireworks

18. Halides
Form when atoms containing fluorine, chlorine, iodine, or bromine (halogens) combine with potassium or calcium
Halite (NaCl) is better known as rock salt
Fluorite can have many different colors
Fluorite
Halides are often used in making fertilizers

19. Oxides
Compounds formed when elements like aluminum or iron bond with oxygen
Corundum (Al2O3) and Magnetite (Fe3O4) are important oxides
Are used in abrasives and airplane parts

20. Sulfates Minerals containing sulfur and oxygen (SO4)
Gypsum (CaSO4 * 2H2O) is a common example
makes the white sand at White Sands National Monument in NM
Gypsum
Sulfates are commonly used in cosmetics, toothpaste and paints

21. Sulfides
Minerals containing one or more elements such as lead, iron, or nickel combines with sulfur
Galena (PbS) is a sulfide
Sulfides are used to make batteries, medicines and electronic parts
Galena

22. Composition of the Earth’s Crust
Eight Elements that make up over 98% of Earth’s Crust
- Oxygen (O)
- Silicon (Si)
- Aluminum (Al)
- Iron (Fe)
- Calcium (Ca)
- Sodium (Na)
- Potassium (K)
- Magnesium (Mg)

23. Where Do Minerals Come From?
In general, minerals form in two ways:
Cooling magma - Crystallization of melted materials
From solution - Crystallization of materials dissolved in water
Magma
a. At the surface
b. Beneath the surface
Evaporation

24. Magma
Magma is molten material from the mantle that hardens to form rock.
Lava is magma that reaches the surface.
Minerals form as hot magma cools inside the crust, or as lava hardens on the surface.
When these liquids cool to the solid state, they form crystals.

25. Size of Crystals Depends of several factors:
The rate at which the magma cools
Depends of several factors:
The chemical composition of the magma
The amount of gas the magma contains
When magma remains deep below the surface, it cools slowly over many thousands of years.
Slow cooling leads to the formation of large crystals.
Magma closer to the surface cools much faster, producing smaller crystals.

26. Minerals from Hot Water Solutions
Sometimes, the elements that form a mineral dissolve in hot water and form a solution.
A solution is a mixture in which one substance dissolves in another.
When a hot water solution begins to cool, the elements and compounds leave the solution and crystallize as minerals.
This can happen on the ocean floor when ocean water seeps down through cracks in the crust.

27. Minerals formed by Evaporation
Minerals can also form when solutions evaporate. Example: salt from sea water
Several other useful minerals also from by the evaporation of seawater:
Gypsum
Calcite crystals
Minerals containing potassium

28. Minerals formed by Metamorphism
When rocks are put under extreme heat and pressure, the chemical composition of the rock can change, forming new minerals.
Examples: calcite, garnet, graphite, hematite, magnetite, mica and talc.

29. How Are Minerals Identified?
Color
Luster
Hardness
Streak
Density
Crystal Shape
Cleavage and Fracture
Special Properties

30. Color Usually the first and most easily observed
Not a reliable way to identify a mineral
- Some minerals are the same color as others
- Some minerals can have many colors
ROSE QUARTZ
QUARTZ
SMOKY QUARTZ

31. Luster General appearance of a mineral surface in reflected light
Glassy-Obsidian

32. Examples of luster Metallic Vitreous: similar to glass
Resinous: resembles the way plastic reflects light
Pearly: resembles the way pearls shine
Greasy: resembles the way petroleum jelly or a greasy surface reflects light
Silky: resembles the way silk reflects light
Earthy: dull, may be rough or dusty
Waxy
Adamantine: resembles the way a diamond shines
Fibrous – looks like fibers
Pitchy – looks like tar

33. Hardness Resistance to scratching by different items; “scratchability”
Mohs Hardness Scale is used to determine the hardness of minerals by comparing them to substances of known hardness.

34. Mohs Mineral Hardness Scale
1) Talc
2) Gypsum
3) Calcite
4) Fluorite
5) Apatite
6) Feldspar
7) Quartz
8) Topaz
9) Corundum
10) Diamond
Softest 1 9 5 2 6 10 3 7
Hardest 4 8

35. Streak The color of a finely powdered mineral
Determined by rubbing the mineral on a piece of unglazed porcelain (streak plate)

36. Density
The amount of matter in a given space
Specific Gravity is the comparison of a substance’s density to the density of water

37. Crystal Shape
Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming

38. Cleavage and Fracture
Cleavage is the tendency of a mineral to split or crack along parallel or flat planes.
Fracture occurs when a mineral breaks at random lines instead of at consistent cleavage planes.
BIOTITE
QUARTZ
Obsidian
1 Direction of Cleavage
No Cleavage
Conchoidal Fracture

39. Fracture

40. Special Properties Magnetism (Magnetite)
Glowing under ultraviolet light (Fluorite)
Taste (Halite)
Smell (Sulfur)
Reaction to HCl (Calcite)
Double refractive - a thin, clear piece of calcite placed over an image will cause a double image
Radioactivity - minerals containing radium or uranium can be detected by a Geiger counter

41. Economic Importance of Minerals
Minerals are in many things we see and use everyday such as; bricks, glass, cement, plaster, iron, gold

42. Every American Requires 40,000 Pounds of New Minerals per Year
At this level of consumption the average newborn infant will need a lifetime supply of:
- 795 lbs of lead (car batteries, electric components)
- 757 lbs of zinc (to make brass, rubber, paints)
lbs of copper (electrical motors, wirings
lbs aluminum (soda cans, aircraft)
- 32,700 lbs of iron (kitchen utensils, automobiles, buildings)
- 28,213 lbs of salt (cooking, detergents)
- 1,238,101 lbs of stone, sand, gravel, cement (roads, homes)