Physical Properties
1-2 Mineral Identification
• Since all minerals have unique features,
geologist use seven different aspects to
identify them.
Objectives:
• List the physical properties used to identify minerals.
•Describe how hardness and streak are used to identify
minerals.
Mineral Appearance
• The color and appearance of a mineral is
one way that minerals can be identified.
However, most minerals can not be
identified by color alone.
• Minerals can also be described as rough,
glassy, smooth or grainy.
Hardness
• The Mohs Hardness Scale is used to test
how easily a mineral can be scratched. It
lists 10 minerals and rates them from 1-10
based on their hardness.
• Minerals can only be scratched by a
mineral that is higher on the Mohs
Hardness Scale.
• Talc 1 – Diamond 10
Luster
• Luster describes how light is reflected from
a mineral’s surface.
• Metalic minerals look like metal.
• Non-metallic means that is does not shine
like metal. They can look, glassy, pearly,
silky, and dull.
Streak
• Streak is the color of the mineral when it is
broken up and powdered. The streak
color is not always the same color as the
mineral. For example, pyrite has a gold
color, but it leaves a dark colored streak.
Specific Gravity
• Minerals can be distinguished by
comparing the weights of equal sized
samples.
• Gold is heavier than pyrite.
Cleavage and Fracture
• The way a mineral breaks is another way
to identify it. Some minerals break in flat
sheets like mica. This is called cleavage.
Other Properties
• Some minerals have unique properties.
• Magnetite is attracted to magnets.
• Calcite will show a double image and fizz
when acid is put on it.
• Other minerals break with rough edges
like quartz. This is called fracture.