Transcript Section-2 Mineral Identification pg.68

 Describe physical properties used to identify
minerals.
 Identify minerals using physical properties
such as hardness and streak.
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Mineral appearance
Hardness
Luster
Specific gravity
Streak
Cleavage and fracture
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What it looks like
What color is it?
Which one of the following is gold? Identify by
appearance.
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A measure of how easily a mineral can be
scratched
Mohs Hardness Scale
Mineral
Rating
Testing Method
Talc
1
Softest known mineral. It flakes easily when
scratched by a fingernail.
Gypsum
Calcite
2
A fingernail can easily scratch it.
3
A fingernail cannot scratch it, but a copper
penny can.
Fluorite
Apatite
Feldspar
4
A steel knife can easily scratch it.
5
A steel knife can scratch it.
6
Cannot be scratched by a steel knife, but it
can scratch window glass.
Quartz
Topaz
Corundum
Diamond
7
Can scratch steel and hard glass easily.
8
Can scratch quartz.
9
Can scratch topaz.
10
Hardest known mineral. Diamond can
scratch all other substances.
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The way a mineral reflects light is luster.
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Luster is either metallic or nonmetallic.
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Specific gravity can be compared to density.
The specific gravity of a mineral is the ratio of
its mass compared with the mass of an equal
volume of water.
Gold has specific gravity of 19.
It means gold is 19
than water.
times more dense
Gold is
19 times heavier,
19 times more dense
than water.
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When a mineral is rubbed across a piece of
porcelain tile a streak of powdered mineral is
left behind.
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Cleavage is the way a mineral breaks along
smooth, flat surfaces.
Mica and calcite have cleavage.
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Minerals that break unevenly with rough or
jagged surfaces have fracture.
Quartz has fracture.
quartz
CLEAVAGE
FRACTURE
http://www.youtube.com/watch?v=VnM8ebB06MU
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Gems (or gemstones) are highly prized
minerals because they are rare and beautiful.
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They are cut to sparkle.
Amethyst gets its purple color from a bit of iron.
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Cullinan diamond
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Found in S. Africa in 1905
Largest uncut diamond ever found
Cut into 9 main stones and 96 smaller ones
Largest is called “Great Star of Africa.”
Belongs to the British monarchy.
Hope diamond
Most famous gem
 Blue in color
 Thought to be cursed
 In the Smithsonian in Washington, DC
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Waste diamonds are used in industry as
abrasives and embedded on cutting tools, such
as saw blades and drill bits.
Quartz crystals are used in electronics and in
timepieces. They vibrate and can control
frequencies.
Rubies and emeralds are used in lasers.
Most industrial gems are synthetic, meaning
manmade.
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Minerals are often found in ores.
Ores are minerals or rock that contains a useful
substance AND can be mined at a profit.
Bauxite
Yields aluminum through smelting.
 Smelting is a process where a rock is crushed and the
metals are melted out of the rock.
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Hematite and magnetite
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Yield iron used in construction, cars, and many other
applications where steel is needed.
Ilmenite and rutile
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Yield titanium
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Some metallic elements can dissolve in fluids.
These fluids travel through cracks in rocks and
form mineral deposits
These are called vein minerals.
Includes:
gold
 silver
 copper
 zinc
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Titanium is used in
 Auto body parts
 Tennis rackets
 Bicycles
 Wheelchairs
 Glasses frames
 Replacement joints