SILICATES and OTHER MINERALS
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NAME_________________________
Please answer all of the questions:
(1) (11 points)
What charge would you assign to the following atoms or species in common rock-forming minerals?
What type of coordination / site do the cations occupy in common silicate minerals? (if an element occurs in more than one type of site, give one)
CHARGE SITE
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(a) Si=
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(b) Al=
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(c) Mg=
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(d) Fe=
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(e) Li=
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(f) K=
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(g) Ca=
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(h) Ti=
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Which minerals may contain the constituents listed below?
CHARGE EXAMPLE OF MINERAL CONTAINING THIS
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(i) F=
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(j) Cl=
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(k) OH=
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(2) (5 points)
(a) What is the charge on oxygen?
(b) What do we mean by the term "bridging oxygen"?
(3) (13 points)
(a) Draw a simple I-beam representation of an amphibole, and show how the I-beams are arranged:
(b) What element is most commonly found in the M4 site of amphibole?
(c) Mark the A-sites and the cleavages on your diagram.
(d) How do these cleavages compare with those found in pyroxene?
(4) (8 points) Give two examples of cyclosilicates (ring silicates) and note the rock-types that we may expect to find these minerals in:
(a) (b)
Found..................................................... Found..........................................
(5) (6 points) Name two quartz (SiO2) polymorphs that are related by a reconstructive transformation:
(6) (8 points) In approximately one sentence explain the consequence of:
(a) cation ordering on the symmetry of feldspars?
(b) inserting cations into the interlayer of sheet silicates on the physical properties?
(7) (15 points) Briefly describe in your own words the meaning of the terms:
(a) exsolution
(b) solid solution
(c) trioctahedral
(8) (4 points) Name one mineral whose presence in a rock would indicate high-pressure and relatively low-temperature conditions?
(9) (5 points)
(a) What is the chemical formula for olivine?
(b) What type of silicate is it?
(10) (4 points)
(a) What is the chemical composition of kyanite?
(b) In what type of rocks would you expect to find this mineral?
(11) (4 points) Which of the following would we expect to be stable in the mantle, answer Yes or No:
(a) chlorite ..................
(b) olivine ....................
(c) tridymite .................
(d) kaolinite .................
(12) (9 points)
(a) How does a pyroxenoid differ from a pyroxene?
(b) Name one pyroxenoid:
(c) and give its chemical formula:
(13) (10 points)
(a) What is the general formula for garnet?
(b) Name 5 elements other than Si and O commonly present in garnets?
(14) (8 points) Give the silicate group (i.e. chain silicate, framework silicate) to which each of the following minerals belong:
MINERAL GROUP
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Topaz...............................................................
Orthoclase.......................................................
Chlorite............................................................
Humite.............................................................
Cristobalite.....................................................
Vesuvianite.....................................................
Grunerite..........................................................
Lepidolite........................................................