Exercise 4. Simple Phase Diagram

This exercise is due on Oct 15, 2014.

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Phase diagrams are commonly and widely used to depict the stability of minerals. Rocks can be though of as chemical systems. The state of the system, that is, the amount and compostions of the minerals in the rock, is “mapped" on a diagram showing temperature, pressure, composition, and any other environmental variables that affect the state. Here is the simple but important example of plagioclase.

Phases in the two-component system albite–anorthite at 1 atm. The phase diagram was originally determined in 1913 from experiments conducted by N. L. Bowen

Be sure to learn about tie-lines and the lever rule!


Geology 310 © Theodore C. Labotka 2014