Download Minerals of Earth*s Crust

Chapter 5
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Inorganic
Occurs naturally
Crystalline solid
Consistent
chemical
composition
Gypsum
Fluorite
Ice?
Salt?
Sugar?
Charcoal?
Rock?
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Scientists have identified 3,000 minerals
Of those minerals, there are 20 common
rock-forming minerals
All minerals are divided into 2 main
groups: Silicate and Nonsilicate Minerals
Silicates
Nonsilicates
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Must have Silicon and Oxygen
Usually has additional elements like Ca, Na, K,
Fe, or Mg
96% of Earth’s crust
Quartz and feldspar make up more than 50% of
the crust
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Do not contain silicon and oxygen
Make up 4% of Earth’s crust
There are 6 major classes
Mineralogists identify minerals based on a
number of specific physical properties:
Color
Streak
Luster
Cleavage and Fracture
Hardness
Crystal Shape
Density
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Easy to observe
Unreliable
Trace amounts of
elements can
change color
Weathering can
change color
The same mineral
can come in
different colors.
Rubies are cut from corundum
with traces of Chromium (Cr)
Sapphires are cut from corundum
with traces of Cobalt (Co)
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Color of the
mineral in the
powder form
More reliable than
color
Use a streak plate
Minerals that are
harder than the
streak plate will
leave no streak
because it is too
hard to rub off on
the plate
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Light reflected from the mineral’s
surface
Metallic luster
Nonmetallic luster: waxy, pearly, glassy,
dull/earthy, or vitrious/brilliant
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Cleavage is the
tendency of a
mineral to split
along specific
planes of
weakness to form
smooth, flat
surfaces
Cleavage in three directions. Example: CALCITE
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Fracture is when
the mineral does
not split along
cleavage planes
Fracture can be
irregular, fibrous,
or conchoidal
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A measure of the
ability of a mineral to
resist scratching
Hardness relates to
the strength of
bonds between the
minerals atoms (Ex:
Diamond vs.
Graphite)
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To determine an unknown mineral’s
hardness, you need to scratch it against
a mineral of known hardness
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TETRAGONAL, ORTHORHOMBIC,
HEXAGONAL, TRICLINIC, MONOCLINIC,
ISOMETRIC
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Ratio of mass to
volume of a
substance
Density = mass/volume
Lead
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Most minerals have a
density between 2
and
3 g/cc
Density = 11.35 g/cc
Galena
Density = 7.6 g/cc
Fluorescence – ability
to glow under UV light
Double Refraction –
light is bent to
produce a double
image
Magnetism
Radioactivity