Review Questions for Lecture 17:  Earth's Crust;
Nesosilicates, Sorosilicates

1. Compare and contrast the three Al-silicate polymorphs in terms of
    structure and P-T space.

2.  If all three polymorphs occur together in a rock, what would it tell you
    about the rocks formation?

3. What are the geologic environments, e.g. P, T, or composition, indicated by:

4. Why is zircon important to geologists?
    What does it have in common with monazite?

5. What minerals compose a greenschist? What kind of rock is a greenschist?

6. BONUS: Why is zircon considered a good material for disposal of high level
    radioactive waste?