Ch 3 Minerals
Worlds largest diamond mine
Layers of the Earth
Crust (8 to 32 km)
Mantle (2900 km)
Liquid Core(2250 km)
Solid Core (1300 km)
Core
1. Solid Inner Core:
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Made of solid Nickel and Iron
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Under great pressure resulting in a solid form.
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Iron causes the Earth to be
magnetic
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5000 degrees Celsius
2. Liquid Outer Core
Made of liquid Nickel and Iron
2200 degrees Celsius
Mantle
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Molten, liquid rock (Magma)
Makes up about 80% of Earth’s
volume
Ranges from 870 to 2200 degrees
Celsius
Crust and Mantle divided by the
Moho Boundary
Crust
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Very thin, solid layer of rock
Made of mostly Silicon &
Oxygen (75%)
What are Minerals?
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Naturally occurring –
not man-made, in the earth
Inorganic –
doesn’t come from living things
Always a solid –
has volume and shape
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Definite chemical composition –
made of a single pure
substance or element
Crystalline form –
flat sides, sharp edges &
corners
Formation & Composition
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As hot magma cools, the
minerals will crystallize.
If the magma cools very slowly it
forms large crystals. If it cools
very quickly it forms tiny to
microscopic crystals.
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Some mineral crystals will form
compounds dissolved in
liquids. Minerals will be left
behind when the liquid
evaporates.
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The eight most common elements
in the crust form a large number of
the known minerals.
(O, Si, Al, Fe, Ca, Na, K, & Mg)
The compound formed by Silicon &
Oxygen is known as Silicate.
Mineral Identification
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The identification of a
mineral is based on its
physical properties
1. Color
• Some minerals have characteristic
colors
• Some minerals can come in several
different color varieties
EX: Quartz & Corundum
Some of the colors can change due to
temperature, pollution, or radiation.
2. Luster
The way a mineral reflects light
off its surface.
• 2 types
A. Metallic – very shiny, looks like a metal
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B. Non-metallic Glassy – shiny, transparent, translucent
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Earthy - clay-like, dull
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Pearly: pearl-like
3. Hardness
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The ability for a mineral to
resist being scratched.
Mohs Hardness Scale
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A list of ten minerals ranked
according to hardness.
1= softest (talc)
10=hardest (diamond)
1. Talc
5. Apatite
2. Gypsum
6. Feldspar
9. Corundum
3. Calcite
7. Quartz
4. Fluorite
8. Topaz
10. Diamond
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A mineral that is higher on the scale
will scratch the mineral that is lower.
Other common items have been given
ratings on the scale for identification
purposes.
EX: Fingernail, Penny, File, Glass
4. Streak
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The color of the powder scraped off a
mineral when rubbed against a rough
surface (streak plate.)
Very useful property for showing the TRUE
color.
Same color always, no matter what the
variation
5. Breakage
2 types –
a. Cleavage - breaks in smooth, definite
surfaces
• Same every time
b. Fracture - breaks in rough or jagged
surfaces
6. Crystal Form
• Geometric crystals with
flat surfaces and definite
edges
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Cubic
Hexagonal
Tetragonal
Orthorhombic
Monoclinic
Triclinic
• Different from cleavage
7. Other Properties
1.
2.
3.
4.
Reaction to Acid some minerals will bubble
in acid
Magnetism some special minerals
will be magnetic
Sulfur
Smell some will have distinct odors
Taste some have a distinct taste
Halite
Calcite
Mineral Groups
1. Silicates
• Most common mineral family
• Silicon-oxygen tetrahedron (SiO4)
along with additional elements.
• Joined together into chains, sheets,
or 3-demensional networks.
EXAMPLES: Feldspars, Quartz, Micas
2. Carbonates
• Carbonates are used in cement & lime.
• Made of Carbonate (CO3) with other
elements.
EXAMPLES: Calcite & Dolomite
3. Halides
• Used in steel making, fertilizer, & salt
EXAMPLES: Halite & Fluorite
4. Sulfates
• Used in plaster.
• Made of Sulfate (SO4) with other
elements.
EXAMPLE: Gypsum
5. Oxides
• Have Oxygen as a major component.
EXAMPLES: Hematite, Magnetite,
Corundum, & Ice
6. Native Elements
• Minerals of great economic value that
are pure elements.
EXAMPLES: Gold, Silver, Diamond (C),
Sulfur, Graphite (C), Copper,
Platinum
Uses for Minerals
1. Ores
Minerals or combinations of minerals from
which metals and nonmetals can be
removed in usable amounts.
Examples: Cinnabar (Mercury),
Bauxite (Aluminum),
Hematite (Iron)
• Smelting- when an ore is heated so that
a metal can be separated from it.
• Alloys- when pure metals are combined
to form other metallic substances.
(Steel
& Brass)
2. Gemstones
• Minerals that are hard,
beautiful, and durable.
• They are substances that can
be cut & polished for jewelry &
decoration.
a. Precious Stones
• The rarest & most valuable.
Ex: Diamonds, Rubies, Opals,
Sapphires, & Emeralds
b. Semiprecious Stones
• The other gemstones
Ex: Amethysts, Zircons, Garnets,
Turquoises, Jades, & more
c. Non-Mineral Gemstones
• Come from living things
Ex: Amber, Pearls, & Coral