Mass Balance and Mineral Reactions

Dexter Perkins

University of North Dakota

Summary

This is a short exercise to make sure that students understand mass balance and how the different starting assemblages may lead to different results after metamorphism. It is quick but not trivial.

Context

Audience:

Introductory Petrology

Skills and concepts that students must have mastered:

Students should know what a mineral reaction is and they should know the basic implications of PT phase diagrams.

How the activity is situated in the course:

I use this exercise to help students focus their thinking on the idea of mass balance. This exercise is, surprising to me, not easy for some students to complete. So, the exercise provides a good check and leads to further discussion as needed.

Goals

Content/concepts goals for this activity:

The students learn to use phase diagrams and how to determine the ways that mineral assemblages change during metamorphism.

Higher order thinking skills goals for this activity:

This exercise helps students make the connection between phase diagrams (abstract) and real mineral assemblages (concrete).

Other skills goals for this activity:

None.

Description of the activity/assignment

This is a short exercise to make sure that students understand mass balance and how different starting assemblages may lead to different results after metamorphism. It is quick but not trivial.

I use this in class and find that students have some difficulties. The exercise then provides the focus of discussion as we work through the difficulties and work toward better conceptual understanding.