Chapters Covered by Exam #2:

In Nesse, Introduction to Mineralogy
• Chapter 3 - Lots of fundamentals here - structure, size, charges of atoms and ions, electron configurations; Types and Properties of Chemical Bonds
• Chapter 4 - Again, many fundamentals - Pauling's Principles, Mineral Structures, Polymorphism, Classification, Compositional Variation, Mineral Formulas, and Graphical Representation - all important
• Chapter 5 - Crystal Growth & Defects

Some examples of essay-type questions:

• Identify three types of chemical bonds. How are electrons shared in each of the bond types you identified? What physical properties are associated with each bond type?
• Describe the electron configuration of Mg (Z=12). How many electrons are found in the outermost shell of Mg? In geologic materials does Mg behave as a cation or anion? Why?
• Given a structure model of Mineral X: What is the coordination polyhedra of the silver balls? What are the charges of each of the elements that make up this mineral? Determine the electrostatic valency (bond strength) of the bonds between the ions represented by the red and silver balls. What sort of solid solution can this mineral have? What is the basis for this solid solution?
• Give an example of a pair of isostructural minerals. Give an example of a pair of polymorphic minerals. Which type of polymorphism is displayed by the minerals you identified? Describe another type of polymorphism. What is the difference between polymorphism and solid solution?
• Describe the relationships between the solid solution series in the plagioclase and alkali feldspars. Are they complete or partial solid solutions? What chemical exchanges constitute each solid solution series?
• Describe the four types of point defects in minerals. What is a Buergers vector and what types of defects does it describe? Why is a mineral grain boundary considered a planar defect?

Some examples of multiple choice-type questions:

1. An atom that has gained electrons is called a(n) ____________ and has a ______________ charge.
   1. cation; positive
   2. cation; negative
   3. anion; positive
   4. anion; negative
   5. isotope; neutral

2. Which of the following is not a type of valence-related bonding?
   1. hydrogen bonding
   2. covalent bonding
   3. ionic bonding
   4. metallic bonding
   5. All of the above are valence-related bonding types.

3. The cation illustrated here has ____________ or _____________ coordination.
   1. 3-fold; trigonal
   2. 4-fold; tetrahedral
   3. 6-fold; octahedral
   4. 8-fold; octahedral
   5. 12-fold; dodecahedral

4. Growth rates in minerals will usually be fastest ____________________.
   1. parallel to the c-axis
   2. in the direction of the shortest dimension of the unit cell
   3. in the direction of the longest dimension of the unit cell
   4. in the [111] direction
   5. away from the center of the Earth regardless of crystallographic orientation