GEOS 306 – MINERALOGY FALL 2004 – LAB MIDTERM – PAGE 1 OF 9
NAME
DATE
Mineralogy Lab Midterm
You may use a calculator on this test.
You have 45 minutes to complete PART I.
You may use your lab notes for PART II.
PART 1.
1. (10 pts.) Give formulae for the following minerals:
corundum
chalcopyrite
grossular
fayalite
zircon
muscovite
tremolite
GEOS 306 – MINERALOGY FALL 2004 – LAB MIDTERM – PAGE 2 OF 9
sillimanite
dolomite
sanidine
2. (2 pts.) List the minerals of the Mohs hardness scale
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2
3
4
5
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7
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9
10
GEOS 306 – MINERALOGY FALL 2004 – LAB MIDTERM – PAGE 3 OF 9
3. (4 pts.) Draw a ternary diagram of the feldspar series. Include 1) chemical formulae
and 2) names of end members (one at each corner). Label plagioclase series and K-feldspar
series in the appropriate fields.
4. (4 pts.) Draw a ternary diagram of pyroxene. Include the correct chemical formula at
each corner. Give names of the 2 orthopyroxene and 2 clinopyroxene end members.
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5. (10 pts.) For each of the following, (1) solve for the cation valence, (2) suggest a likely
cation for the structure, and (3) name the mineral.
Valence
R?3Al2(SiO4)3
R?2SiO4(OH)2
R?F2
RCO3
R?AlSi2O6
Likely cation
Mineral Name
GEOS 306 – MINERALOGY FALL 2004 – LAB MIDTERM – PAGE 5 OF 9
6. (4 pts.) Symmetry
(a) Draw the unit cell of an orthorhombic crystal. Also, describe the relations of a, b, c and
α, β, γ.
(b) What is the crystal system of the model?
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7. (6 pts.) Silicate Structures
Match each formula to the appropriate silicate polymer structure.
If you don’t have these memorized, you can figure out the answers by considering how many
oxygens each silicon tetrahedron is sharing with other tetrahedra. Remember, each tetrahedron
can share one, two, three, etc., oxygens with bordering tetrahedra.
GEOS 306 – MINERALOGY FALL 2004 – LAB MIDTERM – PAGE 7 OF 9
PART 2. MINERAL IDENTIFICATION
(60 pts) There are thirty minerals to identify, one mineral per station. You will be given three
minutes to examine a sample, then you must move to the next sample. After everyone has
viewed all of the samples, you may return to any samples that you may wish to re-examine.
You may use your textbooks, field guides, and lab notes. You may also use streak plates,
hardness kits, and magnets to identify these minerals. For each sample, fill in the distinctive
properties you observe in the table below. The distinctive properties include color, luster,
habit, cleavage, hardness, heft, etc., or combinations of these (Do not list all these properties
but please list only the characteristic properties that are keys to identification of each
mineral). You will receive full credit (2 points) for each properly identified mineral, in which
case the grader shall ignore the distinctive properties. For unidentified and improperly identified
minerals, correctly listing distinctive properties may earn up to 1 point of partial credit.
Misspelled mineral names result in 1 point penalties.
SAMPLE
1
2
3
4
5
6
7
IDENTITY
DISTINCTIVE PROPERTIES
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