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Group A—Continued Group B—Continued
5. Compare the mineral moissanite (SiC, hardness of 9.2) to the 5. Compare the mineral halite (NaCl, hardness of 2.5) to diamond,
Mohs index mineral fluorite, which has the chemical formula which is pure carbon chemically bonded to itself in a network.
CaF 2 . Are the mineral’s chemical bonds covalent, polar covalent, Are the mineral’s chemical bonds covalent, polar covalent, or
or ionic? Which mineral is softer? ionic? Which mineral is harder?
6. Olivine is a single tetrahedra silicate while hornblende is a 6. Mica is a sheet silicate while quartz is a network silicate. On the
double-chain silicate. On the basis on its silicate structure, which basis on its silicate structure, which mineral has a higher
mineral has a higher percentage composition of silicon? (Silicon percentage composition of silicon? (Silicon to oxygen ratio is 2:5
to oxygen ratio is 1:4 for a single tetrahedra mineral and 4:11 for for a sheet and 1:2 for a network.)
a double-chain mineral.)
7. Galena is a major lead ore mineral and has the chemical formula 7. Magnesite is a magnesium ore mineral and has the chemical
PbS. What is the percentage of lead in galena? formula MgCO 3 . What is the percentage of magnesium in
magnesite?
8. Chalcopyrite and chalcocite are copper ore minerals. On the 8. Magnetite and hematite are iron ore minerals. On the basis of
basis of their chemical formulas, which mineral has a higher their chemical formulas, which mineral has a higher percentage
percentage of copper? (Chalcopyrite is CuFeS 2 , chalcocite is of iron? (Magnetite is Fe 3 O 4 , hematite is Fe 2 O 3 .)
Cu 2 S.)
6
9
9. A lead mine has an ore deposit estimated at 1.69 × 10 metric 9. An iron mine has an ore deposit estimated at 3.53 × 10 metric
tons (tonnes). Assays of the deposit indicate it has a galena tons (tonnes). Assays of the deposit indicate it has a hematite
content of 8 percent by mass. How many tonnes of lead can content of 56 percent by mass. How many tonnes of iron can
potentially be obtained from the deposit? (Assume full recovery.) potentially be obtained from the deposit? (Assume full recovery.)
10. An ore deposit consisting of calcite and galena occurs in a vein 10. An ore deposit consisting of chert and hematite occurs in a
measuring 500 m long by 100 m wide by 25 m high. The deposit deposit measuring 2,500 m long by 1,800 m wide by 75 m high.
has an average specific gravity of 3.2. How many tonnes of lead The deposit has an average specific gravity of 4.3. How many
can potentially be obtained from the mine? (Specific gravity can tonnes of iron can potentially be obtained from the mine?
be converted to density by multiplying by the density of water. (Specific gravity can be converted to density by multiplying by
3
3
Assume SG galena = 7.5, SG calcite = 2.7, and g/cm = tonne/m .) the density of water. Assume SG hematite = 5.3, SG chert = 2.5, and
3
3
g/cm = tonne/m .)
11. For a given igneous rock type, the proportion of the minerals 11. For a given igneous rock type, the proportion of the minerals
present in the rock is read from the percentages on the y axis of present in the rock is read from the percentages on the y axis of
the chart. This proportion varies with the silica content. Based the chart. This proportion varies with the silica content. Based
on Figure 17.13, what is the percentage of each mineral in on Figure 17.13, what is the percentage of each mineral in
andesite at the high silica boundary of its range shown on the andesite at the low silica boundary of its range shown on the
chart? chart?
12. Based on Figure 17.13, what is the average percentage of each 12. Based on Figure 17.13, what is the average percentage of each
mineral in granite? (Assume the average is the middle of the mineral in basalt? (Assume the average is the middle of the basalt
granite column of the chart.) column of the chart.)
13. A granite countertop measuring 4.57 m long by 0.75 m wide by 13. A gabbro countertop measuring 4.70 m long by 0.80 m wide by
2.3 cm thick is being installed in a kitchen. What is the mass of 2.50 cm thick is being installed in a kitchen. What is the mass of
this countertop in kg? (SG granite = 2.75) this countertop in kg? (SG gabbro = 3.0)
14. A limestone building stone measuring 40.0 cm long by 23 cm 14. A sandstone building stone measuring 50.0 cm long by 20.5 cm
wide by 20 cm thick is 90 percent calcite with the rest of its wide by 15 cm thick is 70 percent quartz with the rest of its
volume being empty pore space. What is the mass of this volume being empty pore space. Based on the specific gravity of
building stone in kg? What would be its mass if it were marble? quartz determined in exercise 3, what is the mass of this building
(Recrystallization of metamorphism eliminates the pore space.) stone in kg? What would be its mass if it were quartzite?
(Recrystallization of metamorphism eliminates the pore space.)
15. Granite boulders with a minimum mass of 1.50 tonnes are being 15. Basalt boulders with a minimum mass of 1.50 tonnes are being
used to stabilize a beach. What is the minimum volume of a used to stabilize a beach. What is the minimum volume of a
suitably sized stone in cubic meters? If the stones are spherical, suitably sized stone in cubic meters? If the stones are spherical,
what would be the diameter of the stones in cm? (Assume what would be the diameter of the stones in cm? (Assume
3
3
3
3
SG granite = 2.75 and g/cm = tonne/m .) SG basalt = 3.00 and g/cm = tonne/m .)

17-21 CHAPTER 17 Rocks and Minerals 453