Download How do we identify minerals?

Aim: How do we
identify minerals?
Learning Objective
• Students will describe the properties that
can be used to identify minerals.
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Do Now
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Key Terms
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Physical property
Streak
Luster
Hardness
Cleavage
Fracture
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Physical Properties
• A physical property is the observable
characteristic that describes an object.
• Physical properties help identify minerals.
• Some physical properties of minerals are
color, streak, luster, and hardness.
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Color
• Color is an important property of minerals.
• Color alone cannot be used to identify a
mineral.
• Many minerals are the same color.
• For example, gold and pyrite are both
brassy yellow. Pyrite is called “fools gold”.
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Streak
• The color left by a mineral is called a
streak.
• When a mineral is rubbed across a piece
of unglazed porcelain tile, a streak is left.
• The streak test works only for minerals
that are softer than the streak plate.
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Is it Gold or Not?
• A test to see if you have
found pure gold or pyrite
would be a streak test.
• Gold will leave a yellow
streak and pyrite will
leave a greenish-black
streak.
• So, are those gold
nuggets you have gold?
Pyrite streak
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Luster
• The way a mineral’s
surface reflects light
is called luster.
• Minerals have
metallic or
nonmetallic luster.
• Calcite has a glassy
or a dull luster.
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Hardness
• The property of a
mineral to resist being
scratched is called
hardness.
• Moh’s scale ranks ten
minerals in hardness
from 1 to 10.
• A mineral with a high
number can scratch
any mineral that has a
lower number.
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Cleavage and Fracture
• Cleavage is the
splitting of minerals
into pieces with
smooth, flat surfaces;
the way a mineral
shows cleavage is
always the same for
that mineral.
• Fracture is the
splitting of a mineral
into jagged or uneven
pieces.
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Checking Concepts
1. What property allows one mineral to
scratch another?
2. The color of a powdered mineral on an
unglazed porcelain tile is its ________.
3. The softest mineral on Moh’s hardness
scale is _________.
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Answers
1. Hardness
2. Streak
3. Talc
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The End