Mineral Identification
Anticipation Guide #2
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1) Rocks cannot be made of organic
material
2) Luster is classified as metallic and nonmetallic
3) Scientist use tests to identify minerals
4) Minerals that make up rocks can be
mined as ores
5) A liquid or gas can be classified as a
mineral
VA SOL
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ES 4 The student will investigate and
understand how to identify major rockforming and ore minerals based on
physical and chemical properties. Key
concepts include
 a. properties including hardness, color
and streak, luster, cleavage, fracture,
and unique properties; and.
Objective
3 Define chemical and physical properties of
minerals to include luster, hardness,
cleavage, fracture, streak, color, specific
gravity, and special traits.
Enduring Understanding
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Minerals are the building blocks of rocks.
Mineral Identification
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With more than 3,000 minerals in Earth’s
crust how does one go about identifying
an unknown mineral?
Mineral Identification
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Geologists rely on several simple tests that
are based on a mineral’s physical and
chemical properties. It is usually best to use
a combination of tests rather than just one
to identify minerals
Mineral Properties
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Color is one of the most noticeable but least
reliable characteristics
Mineral Properties
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Sometimes caused by the presence of trace
elements or compounds
Mineral Properties
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Streak is the color of the mineral when it is
broken up into a powder and is a much more
reliable identification method because it rarely
changes
Both of these samples are hematite; both have a reddish-brown streak
Mineral Properties
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Streak is easily determined by rubbing the
mineral across an unglazed porcelain plate
Mineral Properties
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Streak is used to distinguish pyrite from gold
Mineral Properties
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Streak is used to distinguish pyrite from
gold
Mineral Properties
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Luster is the way a mineral reflects light from
its surface and is caused by differences in
mineral chemical compositions
Mineral Properties
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Either metallic or nonmetallic (dull, pearly,
waxy, silky)
Mineral Properties
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Texture describes how a mineral feels to the
touch
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Rough, smooth, ragged, greasy, soapy, glassy
Mineral Properties
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Hardness is a measure of how easily a mineral
can be scratched and is determined by the
arrangement of it’s atoms.
Mineral Properties
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The Mohs hardness scale is used to compare a
sample to the hardness of ten known minerals
Mineral Properties
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Cleavage determines whether a mineral will
split easily and evenly along one or more flat
planes
Mineral Properties
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Mica has perfect cleavage in one direction
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Halite has cubic cleavage (3 planes)
Mineral Properties
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Fracture means the mineral is tightly bonded
and breaks with rough or jagged edges
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Quartz has fracture
Mineral Properties
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Specific Gravity compares the weight of the
mineral to an equal volume of water at 4
degrees C
Mineral Properties
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Special Properties such as light reflection and
reactions to acids are also useful tools
Mineral Properties
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Calcite fizzles when in contact with HCl
Mineral Properties
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Calcite also can cause double images
Mineral Properties
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Magnetite will attract iron
Mineral Properties
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Sulfur produces a rotten egg odor