Teach the Earth > Geochemistry > Teaching Activities > Crystallization of Magmas

Crystallization of Magmas

John Ayers
Vanderbilt University
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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 http://serc.carleton.edu/NAGTWorkshops/review.html.

This page first made public: Jun 28, 2010


Students use three methods to explore the crystallization behavior of a rock of known composition at 1 atmosphere pressure. This laboratory exercise illustrates various approaches used by geochemists and petrologists, and asks the student to critically evaluate them.

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Upper level undergraduate course in Geochemistry or Petrology

Skills and concepts that students must have mastered

How to interpret ternary phase diagrams; optical identification of minerals in grain mounts; use of Excel (and PowerPoint if results are presented to class)

How the activity is situated in the course

Students worked on this laboratory exercise over two 3-hour lab periods. It works best if students are divided into three groups; each group gets a different rock composition; groups take turns working on the three modules; groups then give presentations, showing other students what they learned about their rock.


Content/concepts goals for this activity

Use of phase diagrams;
Performing laboratory and numerical experiments to simulate the earth;
Using diagrams to classify and identify tectonic setting of igneous rocks

Higher order thinking skills goals for this activity

Analyzing data;
Critical evaluation of competing models;
Application of key concepts

Other skills goals for this activity

Working in groups
Oral presentations
Optical mineralogy
Plotting data

Description of the activity/assignment

In this laboratory exercise students explore the crystallization behavior of a rock of known composition at 1 atmosphere pressure using experimental and numerical methods and phase diagrams. They also create and use diagrams to classify their igneous rock and identify its tectonic setting. They compare results of the three methods, and then give a presentation of their results to the class.

Determining whether students have met the goals

I grade the group presentations using a rubric. I also grade each student's answers to the questions in the exercise.

More information about assessment tools and techniques.

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