GEOS 306 MINERALOGY FALL 2006 LAB MIDTERM STUDY GUIDE – PAGE 1 OF 6
Lab Midterm Study Guide
The laboratory midterm will test your knowledge in four main areas: mineral identification,
mineral formulae, mineral chemistry (e.g. valences, solid solutions) and basic crystallography.
Everything you need to know for this exam is contained within your lab handouts. Please ask if
you have any questions or uncertainties.
Mineral ID:
You will need to be able to identify minerals that you studied in the labs. You should focus on
distinctive characteristics of minerals. The best way to study for this section of the exam is to
spend time with the mineral specimens provided during the labs and office hours, and prior to
the exam. For this part of the exam, you may use a cheat sheet (one sheet, front and back), which
can contain mineral names and their physical properties.
Mineral Formulae:
Following is a list of the minerals and formulae that you should know for the exam. Recall that
the best way to memorize formulae is to group minerals. For example, the general formula for
garnets is X3Y2(SiO4)3. Then just remember the cations that go in X and Y for each garnet
member. Note that you can write some formulae in different but equivalent ways: garnet could
be written X3Y2Si3O12. Enstatite can be written MgSiO3 or Mg2Si2O6. Either way is correct, so
choose what is easiest for you. I find that (SiO4)x, for example, is easier to remember than
SixO4x. In the silicates, you can group the feldspars, pyroxenes, garnets, micas and other solid
solutions such as olivine.
Non silicate minerals
gold
iron
graphite
diamond *
rutile
corundum
hematite
ilmenite
perovskite *
spinel *
magnetite
brucite
siderite
azurite
halite
Au
Fe
C
C
TiO2
Al2O3
Fe2O3
FeTiO3
CaTiO3
MgAl2O4
Fe3O4
Mg(OH)2
FeCO3
Cu3(CO3)2(OH)2
NaCl
fluorite
pyrite
galena
sphalerite
chalcopyrite
pyrrhotite
calcite
dolomite
aragonite
anhydrite
barite
gypsum
rhodochrosite
malachite
apatite
CaF2
FeS2
PbS
ZnS
CuFeS2
Fe1–xS
CaCO3
CaMg(CO3)2
CaCO3
CaSO4
BaSO4
CaSO4·2H2O
MnCO3
Cu2CO3(OH)2
Ca5(PO4)3F
GEOS 306 MINERALOGY FALL 2006 LAB MIDTERM STUDY GUIDE – PAGE 2 OF 6
Silicate minerals
quartz (including rock crystal, milky quartz, smoky quartz, amethyst,
citrine, rose quartz, chalcedony, agate, chert, jasper, and petrified wood)
K-feldspar (microcline, orthoclase, and orthoclase)
albite (plagioclase series)
anorthite (plagioclase series)
nepheline
serpentine (antigorite, chrysotile)
kaolinite
talc
pyrophyllite
annite (biotite series)
phlogopite (biotite series)
muscovite
actinolite
tremolite
diopside
hedenbergite
enstatite
ferrosilite
jadeite
spodumene
aegerine
wollastonite
almandine
grossular
andradite
pyrope
spessartine
forsterite (olivine series)
fayalite (olivine series)
kyanite – andalusite - sillimanite
zircon
beryl
titanite
topaz
SiO2
KAlSi3O8
NaAlSi3O8
CaAl2Si2O8
(Na,K)AlSiO4
Mg3Si2O5(OH)4
Al2Si2O5(OH)4
Mg3Si4O10(OH)2
Al2Si4O10(OH)2
KFe3(Si3Al)O10(OH)2
KMg3(Si3Al)O10(OH)2
KAl2(Si3Al)O10(OH)2
Ca2(Mg,Fe)5Si8O22(OH)2
Ca2Mg5Si8O22(OH)2
CaMgSi2O6
CaFeSi2O6
Mg2Si2O6
Fe2Si2O6
NaAlSi2O6
LiAlSi2O6
NaFeSi2O6
Ca2Si2O6
Fe3Al2(SiO4)3
Ca3Al2(SiO4)3
Ca3Fe2(SiO4)3
Mg3Al2(SiO4)3
Mn3Al2(SiO4)3
Mg2SiO4
Fe2SiO4
Al2SiO5
ZrSiO4
Be3Al2Si6O18
CaTiSiO5
Al2SiO4(F,OH)2
Mineral Chemistry:
Revisit the following topics from your labs:
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feldspar ternary diagram (see exercises below)
isomorphs (minerals with the same crystal structure, but different chemical compositions)
olivine solid solution series (forsterite-fayalite)
simple substitution (of cations)
coupled substitution (of cations)
GEOS 306 MINERALOGY FALL 2006 LAB MIDTERM STUDY GUIDE – PAGE 3 OF 6
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determination of valences
single chain silicate valences
pyroxene group ternary diagram (be able to draw it, see exercises below)
Mohs hardness scale
Review your quizzes.
Basic Crystallography and Symmetry:
Be sure you know the names of the six crystal systems, and the definitions of their unit cells.
Remember that a unit cell is defined by six values: the lengths of three non-parallel sides (a,b,c)
and the angles between the sides (α,β,γ). Be familiar with mirror planes, rotational axes (2-, 3-,
4- and 6-fold), and inversion centers. Be able to identify the symmetry elements and crystal
system of plaster models. Especially important are the key symmetry elements of each system
(e.g., cubic forms exhibit four 3-fold rotational axes).
GEOS 306 MINERALOGY FALL 2006 LAB MIDTERM STUDY GUIDE – PAGE 4 OF 6
Sample Questions:
1. Write general formulas for the following mineral groups. (Use symbols for cations).
Sulfates:
Carbonates:
Micas:
Garnets:
Pyroxenes:
K-spars:
Plagioclase:
2. Fill in the feldspar ternary diagram. Be as detailed as you wish, but at least label the three
“end members” with mineral names and compositions.
GEOS 306 MINERALOGY FALL 2006 LAB MIDTERM STUDY GUIDE – PAGE 5 OF 6
3. Give an example, using mineral formulae, of simple substitution.
4. Give an example, using mineral formulae, of coupled substitution.
5. Fill in the pyroxene ternary diagram. Be as detailed as you wish, but at least label the three
“end members” with mineral names and compositions.
6. List the symmetry (mirror planes and rotational symmetry) of the following 2-D shapes:
Rotational:
Mirrors:
GEOS 306 MINERALOGY FALL 2006 LAB MIDTERM STUDY GUIDE – PAGE 6 OF 6
Rotational:
Mirrors:
Rotational:
Mirrors: