1. Minerals

2. How do we use Earth Materials?
Earth Materials: minerals, rocks, and mineral resources (95% to 100% of objects you use)
Extracted Fossil fuel
Raw materials to build homes, etc.
Make up earth’s solid surface (lithosphere).

3. What is a mineral?
Mineral: a naturally occurring, inorganic, crystalline solid that has a definite chemical composition.
1. Naturally Occurring: a mineral must be formed by nature and not made by people.

4. What is a mineral?
2. Inorganic: a mineral CANNOT form from materials that were once part of a living thing.

5. What is a mineral?
3. Crystalline solid: a mineral is always a solid, with its own unique crystal structure.
Crystal Structure: Arrangement of atoms

6. What is a mineral?
4. Definite Chemical Composition: a mineral always contains certain elements in definite proportions.
Quartz is a compound and always contains two oxygen atoms for every silicon atom
Gold is purely Au atoms
Gold
Quartz

8. Mineral or NOT?
Rock salt
AKA Halite
NaCl

9. Mineral or NOT? Beach sand AKA tiny pieces of Quartz SiO2
Crystal shape is a pyramid

10. Mineral or NOT?
Snow
Occurs naturally

11. Mineral or NOT?
An ice cube

12. How are Minerals Related to Rocks?
A rock is any naturally formed solid that is part of Earth or any other celestial object.
Organic or glassy rocks are NOT minerals.
All minerals are rocks, but not all rocks are minerals
Glasses not minerals because their atoms are not arranged in a specific pattern.

13. How are Minerals Related to Rocks?
There is only a small number of minerals commonly found in rocks.
20 – 30 “rock-forming minerals”

15. Mineral Crystal Structure
A mineral’s atomic arrangement is responsible for many of its chemical and physical properties.
Properties: crystal form, breaking pattern, hardness, etc.
The only difference between graphite and diamond (both pure Carbon) is the pattern of the atoms.

16. Silicate Minerals
What two elements, by mass, make up the greatest percentage of the Earth’s crust?
Oxygen & Silicon

17. These two elements combine to form compounds called silicates.
The mineral Quartz is a type of silicate (SiO4)

18. They (Silica and Oxygen) combine in a specific structure called a: Silicon-oxygen tetrahedron.

19. Draw this structure below.Si O O O
Different arrangement patterns result in different breaking patterns, etc.

21. Mineral Formation Minerals can form in TWO ways:
Crystallization of molten material
Crystallization of materials dissolved in water.
Salt on a stone of the Dead Sea, Israel
Crystallization:
when atoms are arranged to form a material with a crystal structure.

22. Massive beams of selenite dwarf human explorers in Mexico's Cave of Crystals, deep below the Chihuahuan Desert. Formed over millennia, these crystals are among the largest yet discovered on Earth

24. Mineral Identification
Each mineral has unique properties that can be used to identify it.
1. Color: the easiest test to do on a mineral, but the least reliable.
Many minerals have the same color.
Some minerals come in MANY colors due to impurities.
Rose Quartz
Citrine
Amethyst

25. Quartz
Halite
Calcite
Corundum

27. Mineral Identification
2. Streak: the color of the powdered mineral
Obtained by rubbing the unknown mineral on a streak plate (porcelain tile).
The mineral Hematite ALWAYS has a red streak
Useless for white or clear minerals, or minerals harder than a streak plate.

28. One way to tell Fool’s Gold apart from real Gold is by their STREAK.
Real gold has a golden streak
Pyrite has a black or dark green streak

30. Mineral Identification
3. Luster: The shine from an unweathered mineral’s surface
Metallic – shines like a polished piece of metal.
Non-metallic – does NOT shine like a metal.
(ex: gold/silver jewelry, an aluminum can)
(ex: glassy, pearly, dull)

31. Metallic luster in Galena Metallic luster in Pyrite
Pearly luster in Muscovite
Earthy luster in Hematite
Glassy luster in Quartz

33. Mineral Identification
4. Hardness: a mineral’s resistance to scratching
The hardness of some common items:
Fingernail – 2.5
A Penny – 3.5
Glass – 5.5
A Streak Plate – 6.5
NOT how easily a mineral breaks
One of the BEST clues in identifying a mineral

35. Mineral Identification
5. Specific Gravity: the density of a mineral compared to the density of water.
The mineral Galena has a high specific gravity

37. Mineral Identification
Cleavage: the tendency of a mineral to break along the zones of weakness
Minerals can have one, two, or several cleavage planes
Forms smooth to semi-smooth parallel surfaces
What determines cleavage?
The way that the crystal’s atoms lines up to form zones of weakness.
Feldspar has TWO cleavage planes
Mica has ONE cleavage plane
Halite (salt) has THREE cleavage planes

39. Splintery fracture in Hornblende Conchoidal fracture in Quartz
Mineral Identification
Fracture: a mineral may break along uneven surfaces.
Mineral has no preferred zones of weakness.
Splintery fracture in Hornblende
Conchoidal fracture in Quartz

41. Mineral Identification
8. Crystal Structure: orderly arrangement of the atoms in the mineral
The geometric shape of a mineral can reflect its crystal structure.
Only visible if individual mineral grains have room to grow freely
Herkimer Diamonds are quartz crystals that have a unique sided geometric shape.

42. Other Ways to Identify Minerals
Acid – Calcite will fizz in weak hydrochloric acid (HCl)
Magnetism – Magnetite will pick up paper clips / staples.
Taste – Halite is rock salt and will taste salty.
Fluorescence – some minerals (mostly forms of calcite) will glow in fluorescent colors under a black (UV) light.
Double refraction – some clear forms of calcite will make a double image of words.

43. Fluorescence of Minerals

44. Double Refraction