Geology Cafe

Introduction to Geology

Quiz 3 - Minerals

1. A mineral with the chemical formula of CaCO3 and has a hexagonal or trigonal crystal shape is:
a) dolomite.
b) calcite.
c) quartz.
d) gypsum.

2. A rock is a:
a) a mixture.
b) composed of one or more minerals.
c) may include non-mineral substances, such as water, gases, or organic matter.
d) b and c.
e) all of the above.

3. Which gemstone is technically a rock but not a mineral?
a) diamond.
b) amber.
c) ruby.
d) sapphire.

4. A mineral that can transmit light, but it is dispersed or cloudy is called:
a) opaque.
b) transparent.
c) translucent.
d) all of the above.

5. Roughly, about how many atoms are in a single crystal grain of salt?
a) 1.2 x 106 (or 1,200,000)
b) 4.5 x 109 (or 4,500,000,000)
c) 13.8 x 109 (or 13,800,000,000)
d) 1.2 x 1018 (or 1,200,000,000,000,000,000)

6. The description of the quality and intensity (sheen or shine) of light reflected off of a mineral, particularly a reflective appearance of the exterior of crystal surfaces is called:
a) luster.
b) fluorescence.
c) specific gravity.
d) double refraction.

7. Examples of sheet silicate minerals include:
a) mica
b) biotite
c) muscovite
d) clay minerals
e) all of the above.

8. The tendency of a crystallized substance to split along definite crystalline planes, yielding smooth surfaces is called:
a) non crystalline.
b) chatoyancy.
c) luster.
d) cleavage.

9. A Geiger Counter is used to:
a) potential facets on a crystal.
b) count the number of elements in a mineral.
c) measure levels of radioactivity.
d) measure the amount of electricity to move through a rock or mineral.

10. "Iceland spar" is a mineral that can demonstrate double refraction—that is, light passing through clear "iceland spar" will transmit a double image, or split a laser beam into two separate beams. Iceland spar is a variety of what mineral?
a) quartz.
b) calcite.
c) feldspar.
d) mica.

Extra Credit:
All crystal shapes that have symmetry axes in equal lengths in 3 directions (at 90º angles to each other) are part of the:
a) trigonal crystal system.
b) isometric crystal system.
c) tetragonal crystal system.
d) triclinic crystal system.