Download Minerals

Minerals
Mrs. Griffin
Hannes Grobe 23:31, 16 December 2006 (UTC
What is a mineral?
• What are some uses of
minerals?
• How do we
differentiate a mineral
from a piece of wood
or a human?
• Minerals & history?
• What is a rock?
Minerals vs. Rocks
• Earth’s crust is composed of ~ 3000
minerals – which play an important role in
forming rocks.
• Rocks are aggregates (mixtures) of
minerals. So . . . minerals are the building
blocks of rocks.
• A question for the future: How do minerals
come together to form a rock?
Minerals
• What is a mineral?

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Naturally occurring (not man-made)
Inorganic, salt vs. sugar
Solid (not made of liquid or gas) with a definite
crystalline structure which give it unique
physical properties.
Solids have definate shapes and volumes
 Most are compounds, quartz: oxygen and silicon

Composition and Structure of
Minerals
• To understand how minerals form, we need
to understand the characteristics of elements
and atoms.
• Chemical Elements

Elements are the basic building blocks of
minerals. There are over 100 known elements.
Composition and Structure of
Minerals
• Atoms
 Atoms are made up of:
 Nucleus, which contains Protons (atomic number)positive electrical charges and Neutrons - neutral
electrical charges (P +N = atomic mass)
 Shells which surround the nucleus and contain
Electrons - negative electrical charges
• The weight (density) of an element depends on the number
of protons and neutrons in the nucleus.
Electron
Nucleus
Structure
of an Atom
Nucleus (neutrons &
protons)
Chemical Compound
Na+
ClNaCl
Combining Elements to Form
Minerals
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Elements combine with each other to form a
wide variety of minerals (chemical compounds)
The new mineral (compound) will have very
different physical properties from the elements
that combined to form it
The atoms in minerals are arranged in regular
geometric patterns
“Definate” Crystalline Structures

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A crystal is a solid in
which the atoms are
arranged in repeating
patterns
Minerals can grow in a
closed or open space
thus determining its
crystalline struture
Chemical Compound
Na+
ClNaCl
“Rock Forming Minerals”
• The most common rock forming minerals
are composed of 8 elements:

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Oxygen (O) , Silicon (Si),
Aluminum (Al) , Iron (Fe), Calcium (Ca)
Sodium (Na) , Potassium (K)
Magnesium (Mg)
• There are just a few dozen minerals that we
call the rock-forming minerals.
Most Common Earth crust elements
Oxygen (46.6%), Silicon (27.7%), Aluminum (8.1%), Iron
(5%), Calcium (3.6%), Sodium (2.8%), Potassium
(2.6%), Magnesium (2.1%)
Composition of the Crust
• The most abundant elements in Earth's crust are:


Oxygen (46.6% by weight)
Silicon (27.7% by weight)
The crust
Mineral Groups
1. Silicates (96% of crust
minerals) - based upon SiO4
Quartz
Feldspar
2. Carbonates – based
upon CO3
calcite
dolomite
rhodochrosite
Carbonates (cont.)
malachite
azurite
3. Oxides – combinations of
metals and oxygen
hematite
magnetite
uraninite
4. Sulfides – combinations
of metal + sulfur
Pyrite – FeS2
Mineral Resources
• Ore - rock that contains useful metallic
minerals that can he mined at a profit.
• Since 98% of the Earth's crust is made up of
8 elements, an element/mineral has to be
concentrated at levels above normal for
profitable mining.
A Rock
is an
Aggregate
of
Minerals
Quartz
Amphibole
Feldspar
Identifying Minerals
• Minerals have lots of different properties
that help us identify them.
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Crystal form, Luster, Color,
Streak, Hardness, Cleavage,
Fracture, Specific gravity,
Taste, Smell, etc.
Mineral Color
• Mineral color is often governed by presence
of Mg, Fe (dark) or absence of these
elements (light).
Mohs hardness scale
10. Diamond
4. Fluorite
9. Corundum
3. Calcite
8. Topaz
2. Gypsum
7. Quartz
1. Talc
6. Potassium Feldspar
5. Apatite
For Next Time
How do minerals
"mix" together to form
rocks?
What is the rock cycle
?