Transcript Earth’s Materials - Lower Hudson Regional Information Center

Earth’s Materials
Minerals – The
building blocks of the
Earth
Minerals
Minerals are substances which are
 Naturally occurring
 Solid
 Inorganic
 Definite composition
 Definite atomic arrangement
Minerals
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There are approximately 4000 known minerals
(some common, some rare)
All are compounds of elements.
Most minerals are composed of 8 elements
Common Elements of Earth’s Crust
Name
Oxygen
Silicon
Aluminum
Iron
Calcium
Sodium
Potassium
Magnesium
Other
Element
Symbol
O
Si
Al
Fe
Ca
Na
K
Mg
Percent by
mass (crust)
46.6%
27.7%
8.1%
5.0%
3.6%
2.8%
2.6%
2.1%
1.5%
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
1.
Mineral Properties/ID
Hardness
The resistance a mineral has to being scratched
2.
Moh’s Hardness Scale
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
3.
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.
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Mineral Properties/ID
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Using the Reference Tables
Mineral Formation 1
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From Magma (molten rock)
–
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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
Mineral Formation 2
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Recrystalization
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–
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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