Download How to Identify a Mineral

How to Identify a Mineral
Mineral Identification
• We identify minerals so we can recognize
valuable resources (useful or beautiful).
Mineral Identification
• There are 7 tests performed on minerals
so they can be identified.
Test 1
Test 1
• Mineral Appearance: Color and
appearance are two clues used to identify
minerals.
Azurite can always
be identified by its
striking blue color.
Test 1
• However, this test is not enough to identify
most minerals.
Which one is gold and which one is iron pyrite (fool’s gold)?
Test 2
Test 2
• Hardness: the measure of how easily a
mineral can be scratched.
Talc can be scratched by a fingernail, diamonds cannot
be scratched by anything but another diamond.
http://www.cnn.com/2012/08/09/living/olympians-bite-medals/index.html
Test 2
• Hardness is measured using a Mohs scale.
Test 3
Test 3
• Luster: the way a mineral reflects light.
Test 3
• A mineral can be metallic or non-metallic,
such as glassy, dull, pearly, or silky.
Non-metallic, dull
Non-metallic, glassy
Metallic
Test 4
Test 4
• Specific Gravity: a mineral’s weight is
compared to the weight of an equal sized
amount (volume) of water.
Gold has a specific gravity of 19, iron pyrite is 5 (= 5 times heavier than water.)
Fake or real???
Test 5
Test 5
• Streak: the color a mineral leaves on a
porcelain tile.
Hematite (on left) looks gray, but leaves a reddish-brown streak. Iron pyrite
(on right) is gold colored, but leaves a greenish-black streak.
Test 6
Test 6
• Cleavage or Fracture: how a mineral
breaks.
Test 6
• Cleavage: the physical property of some
minerals that allows them to break along
smooth, flat surfaces.
Mica always cleaves in thin, flat sheets. Halite cleaves at 90
degree angles.
Test 6
• Fracture: the physical property of some
minerals that causes them to break with
uneven, rough, or jagged surfaces.
Test 7
Test 7
• Other properties: some minerals have
unique properties that allow them to be
easily identified.
Magnetite
will pick up
iron like a
magnet
Test 7
Calcite can
cause
double
images
Test 7
These minerals “glow” in the
mining tunnel when under uv
light
Willemite and
Calcite have
a property
known as
fluorescence,
they will
“glow” under
uv light
Summary
There are 7 tests to determine the identity of a
mineral
1. Color and appearance
2. Hardness
3. Luster
4. Specific Gravity
5. Streak
6. Cleavage and Fracture
7. Other Properties
http://www.youtube.com/watch?v=c7wJP_K_sAQ&feature=related
http://abcnews.go.com/US/oklahoma-teenager-finds-385-carat-canary-diamond/story?id=20633996
Review
1. What are the 7 tests?
Color and appearance
Hardness
Luster
Specific Gravity
Streak
Cleavage and Fracture
Other Properties
Review
2. Why do we sometimes need to do more
than one test?
It may be difficult to identify a mineral based on
only one characteristic. It may share
common features with other minerals.
Review
3. Which test uses the Mohs scale?
Hardness
Review
4. What type of luster do each of the
following minerals have? (Metallic or
Non-metallic)
Metallic, non-metallic, non-metallic, metallic
Review
5. What type of breakage do these minerals
show?
Cleavage, fracture, fracture
Review
6. Which test is being performed here?
Streak Test