Download Geology – Minerals Lab

Geology – Minerals Lab
Geologists use a series of (relatively) simple tests to classify unknown mineral
samples. Instructions for each test are on the lab tables.
1. Using the streaking plate and other tools provided, make observations on your
9 minerals in the following categories:
Calcite
Muscovite
Talc
M
i
n
e
r
a
l
Hematite
F
l
u
o
r
it
e
Color
Streak
Color
Hardness
Luster
Special
Observation
Crystal
Shape
Feldspar
Magnetite
ie
Graphite
Q
u
a
r
t
z
2. Obtain a mystery sample from Ms. Lasee and conduct the same tests to
determine which mineral it is (yes, you must do all the tests even if you figure
it out without them!):
Mineral
Color
Streak
Color
Hardness
Luster
Special
Observations
Crystal
Shape
What do you think your unknown mineral is???
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Testing Minerals
Color: What does it look like? Remember, color is one of the least accurate
ways to identify most minerals, since many minerals come in several colors or
shades.
Streak Color: Rub the mineral sample on the WHITE, CERAMIC streak plate
just hard enough to leave a powder residue. What is the color of the powder?
Some minerals are so hard that they will scratch the plate, and not leave a streak.
Don’t keep trying – just record the information.
Hardness:
Can you flake off a piece with your fingernail? Hardness of 1.
Can you scratch it with your fingernail? Hardness of 2.
Can scratch it with a copper penny but not a fingernail. Hardness of 3.
Can’t scratch it with copper; steel easily scratched it. Hardness of 4.
Able to be scratched with steel. Hardness of5.
Can’t be scratched by steel, can scratch glass. Hardness of 6.
Can scratch glass and steel easily. Hardness of 7.
Can scratch quartz. Hardness of 8.
Can scratch topaz. Hardness of 9.
Can cut hard glass (diamonds only). Hardness of 10.
Luster: How does the surface reflect the light? Is it metallic? Does it seem to
have a rainbow (oily luster)? Does it not reflect much light at all (dull)? Is it
glassy? Opalescent (pearly luster)? You can make up an adjective if none of
these seem to fit.
Special Observations: What else do you notice about it that seems
distinctive?
Crystal Shape: Does the mineral seem to have a distinctive shape? See page
124 of Inside Earth for diagrams of some of the crystal shapes. Look at the
sample under one of the stereoscopic microscopes. Is that shape repeated inside
the mineral sample?