GOchem Exercise 2z

Due 09/19/2005

1. Give the sequence of cosmic abundance for the following elements (most abundant first). Explain why you made these choices.

Au, Ag, Ti, C

2. How does this sequence (question 1) compare with the composition of Earth’s crust (use basalt for oceanic crust and Low-granite for continental crust—Table 4.5 in text). Discuss this comparison.

3. Give the sequence of cosmic abundance for the following elements (most abundant first). Explain why you made these choices.

Ca, Na, Mg, K

4. How does this sequence (question 3) compare with the composition of Earth’s crust (use basalt for oceanic crust and continental shields for continental crust—Table 4.4 in text). Discuss this comparison.

5. In a water-clay environment give the sequence of cation exchange likely for

Ca, Na, Mg, K

6. Discuss the crystallization behavior (substitution) of Hf and Zr.

7. Discuss the crystallization behavior (substitution) of Li and Be.

8. Discuss the relationship of NaAlSi₃O₈ and CuAlSi₃O₈. What can you say about copper feldspar?

9. Place these elements in sequence of crystallization from a magma.

Mg, Fe, Cr, Mn

10. Which of the heavy metals has Jahn-Teller effects in an igneous environment? What are Jahn-Teller effects? Which other ions can have Jahn-Teller effects in more oxic environments than those in question 10?

11. Calculate the mafic index for basalt in Table 4.5 in the text. Also calculate two crystallization indices for Low-granite and High-granite in table 4.5. Which granite is most "primitive?"