Earth

1
Earths Materials

• Minerals The building blocks of the Earth

2
Minerals

• Minerals are substances which are
• Naturally occurring
• Solid
• Inorganic
• Definite composition
• Definite atomic arrangement

3
Minerals

• There are approximately 4000 known minerals (some
  common, some rare)
• All are compounds of elements.
• Most minerals are composed of 8 elements

4
Common Elements of Earths Crust
Name Element Symbol Percent by mass (crust)
Oxygen O 46.6
Silicon Si 27.7
Aluminum Al 8.1
Iron Fe 5.0
Calcium Ca 3.6
Sodium Na 2.8
Potassium K 2.6
Magnesium Mg 2.1
Other 1.5
5
Mineral Properties and Identification
(Reference Tables)

• Luster Metallic or non-metallic
• The way light shines off a fresh surface of the
  mineral
• Most minerals are non-metallic

6
Mineral Properties/ID

• Hardness
• The resistance a mineral has to being scratched

7
Mohs Hardness Scale
8
Mineral Properties/ID

• Cleavage/Fracture
• Cleavage is the tendency of a mineral to break
  along zones of weakness and form smooth, parallel
  sides.
• Fracture is the tendency of a mineral to break in
  random directions

9
Mineral Properties/ID

• Color and Streak
• The color of a mineral can be useful, HOWEVER, it
  can vary due to slight chemical differences
• The streak is the color of freshly crushed
  mineral powder and is usually constant.

10
Mineral Properties/ID

• Using the Reference Tables

11
Mineral Formation 1

• From Magma (molten rock)
• Magma (very hot) begins to cool
• As the magma cools, atoms and molecules begin for
  form compounds
• Compounds merge together to form mineral grains
• Many different minerals can form out of one
  batch of magma

12
Mineral Formation 2

• Recrystalization
• A rock is subjected to high temperature and
  pressure
• Some minerals begin to chemically change without
  melting
• Atoms and molecules recombine in a new way and
  minerals begin to grow