Mass Balance and Mineral Reactions
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.
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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.
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.
Determining whether students have met the goals
This project is not graded. Instead it is used to identify misconceptions. So, the exercise is a success if the students are able to complete it.
More information about assessment tools and techniques.Teaching materials and tips
- Activity Description/Assignment (Acrobat (PDF) 46kB Apr22 09)
- Instructors Notes (Acrobat (PDF) 10kB Jun12 08)
- Solution Set (Acrobat (PDF) 223kB Apr22 09)
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Other Materials
- What Forms Solutions Graphics (Acrobat (PDF) 160kB Apr22 09)
Supporting references/URLs
Teaching Phase Equilibria--visit this site for a complete overview of applications of phase equilibria in igneous and metamorphic petrology.