GEOG 111 Fall 2000

Questions for chapter 2:

1. What do halite, pyrite and galena all have in common? How are they different?

2. We know that all atoms are made from a few basic building blocks and that different isotopes are variations on the same theme.

We know also that minerals are combinations made from a limited number of basic building blocks, and that different polymorphs are variations on a single theme.

Finally we know that among the major mineral groups we may find minerals that are fundamentally similar but which have compositions that differ owing to the phenomenon of ion substitution.

Provide examples of (a) a pair of isotopes; (b) a pair of polymorphs (not including carbon-based minerals); and (c) a mineral pair that are related to each other through ion substitution. In each case explain in detail how the two members of the pair are similar and how they are different in terms of both composition and structure.

3. Explain the difference between plagioclase and orthoclase feldspar. Also explain the difference between anorthite and albite, and how they are related to each other.