Plagioclase Phase Diagram

Dexter Perkins
University of North Dakota
Author Profile

This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

For more information about the peer review process itself, please see

This page first made public: Aug 7, 2006


This short exercise involves the binary plagioclase "two-phase loop" phase diagram.

Used this activity? Share your experiences and modifications



This exercise is designed for a mid/upper-level undergraduate geology course on the principles of mineralogy.

Skills and concepts that students must have mastered

Students should have knowledge of basic chemistry and of minerals equivalent to what they would learn in an introductory geology class.

How the activity is situated in the course

This activity is the 12th of 36 mineralogy exercises and is used towards the beginning of the course.


Content/concepts goals for this activity

  • Students learn how to interpret the plagioclase phase diagram.

Higher order thinking skills goals for this activity

  • Learn how to translate a phase diagram into something meaningful.

Other skills goals for this activity

Description of the activity/assignment

In this short exercise, students examine the plagioclase phase diagram and answer questions about melt composition, temperature and cooling, crystalization, and melt:crystal ratios.

Determining whether students have met the goals

More information about assessment tools and techniques.

Download teaching materials and tips

Other Materials

Supporting references/URLs