Post on 19-Mar-2020
Minerals
Minerals
What is a Mineral?
Naturally Occurring
Inorganic
Solid
Definite Chemical Formula
Definite Crystal Structure
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?
Inorganic
Formed by inorganic processes; not living
Does not contain chains of carbon atoms
Solid
Not gas or liquid
-H2O as ice in a glacier is a mineral, but
water is not
Definite Crystal Structure
Highly ordered atomic arrangement of atoms in regular geometric patterns
8
Apatite Feldspar Diamond Quartz
Definite Chemical Formula
Minerals are expressed by a specific chemical formula
-Gold (Au)
-Calcite (CaCO3)
-Quartz (SiO2)
-Pyrite (FeS2)
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)
Where Do Minerals Come From?
Magma
Evaporation
How Are Minerals Identified?
Color
Luster
Hardness
Streak
Density
Crystal Shape
Cleavage and Fracture
Special Properties
Color
Usually the first and most easily observed
-Some minerals are always the same color
-Some minerals can have many colors
QUARTZ ROSE QUARTZ SMOKY QUARTZ
Luster
General appearance of a mineral surface in reflected light
Glassy-Obsidian
Hardness Resistance to scratching by different
items; “scratchability”
Mohs Hardness Scale >2 fingernail
3 penny
~5 Steel of a pocket knife
5.5 Window Glass
6.6 Steel of a file
7 quartz crystal
Mohs Mineral Hardness Scale
1) Talc
2) Gypsum
3) Calcite
4) Flourite
5) Apatite
6) Feldspar
7) Quartz
8) Topaz
9) Corundum
10) Diamond
Softest
Hardest
1
2
3
4
5
6
7
8
9
10
Streak
The color of a finely powdered mineral
Determined by rubbing the mineral on a piece of unglazed porcelain (streak plate)
Density
The amount of matter in a given space (Mass/Volume)
Crystal Shape
Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming
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
No Cleavage 1 Direction of Cleavage Conchoidal Fracture
Special Properties
Magnetism (Magnetite)
Glowing under ultraviolet light (Fluorite)
Salty taste (Halite)
Smell (Sulfur)
Reaction to HCl (Calcite) Magnetite
Economic Importance of Minerals
Minerals are in many things we see and use everyday such as; bricks, glass, cement, plaster, iron, gold
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) -1500lbs of copper (electrical motors, wirings -3593 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, etc.)