Review Questions for Lecture 20:  Earth's Crust;
    Sulfates, Phosphates, Halides

1. Describe the anion or anionic complex that characterizes these  non-silicate groups?
  What is the bond strength within/outside of the group.
    Where do these minerals cleave?

2.  What geologic conditions are required for sulfates to form?

3. What is the sequence of minerals that form in an evaporite deposit?

4.  Compare and contrast gypsum and anhydrite.

5. The oxidized zone of the Earth occurs where?

6. Apatite is widespread. What does its presence indicate about the chemistry of the rock?

7. What conditions are necessary for halite to form?
8.  Halite is important to the economy of the state of LA. Why?