Review Questions for Lecture 15: Earth's Crust
                Tectosilicates II.

1. Describe the two compositional series of feldspars using a
    triangular diagram. What is the range of solid solution for each
    series and how does it change with Temperature (T)?
2. Why is the alkali series referred to as the "Discontinuous Series"?

3.  Why is the plagioclase series Continuous at all T?
     Using the plagioclase series, explain why igneous melts
      can differentiate.

4.  What polymorphic transformation mechanim relates
     the K-feldspar polymorphs?

5. If microcline occurs in your rock, what can you decipher about
    the cooling history of the rock?

6. What is unique about the zeolite structure?
    Describe, generally, the structure of zeolites?

7. For what two industrial processes are zeolites used?
    Describe these. Why are they useful?

8. How does a feldspathoid differ chemically from a feldspar?

9. What do feldspathoids indicate about the bulk chemistry of the rock in which
they form?