Construction of Crystal Models and Their Graphic Equivalents
Initial Publication Date: May 9, 2008
Summary
This laboratory exercise involves construction of physical and computer models of crystals based on a description of their symmetry. The purpose of the exercise is to help you visualize symmetry in two and three dimensions, and to help you explore the relationships between the different crystal systems. It is a problem-solving exercise: the morphology of the crystal is described in simple terms, and both physical and computer models should meet the requirements of these descriptions. Because the physical models may be used in other laboratory exercises, they should be large enough and precise enough for measurement, and durable enough to take handling.
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Context
Audience
This activity is designed for an undergraduate required course in mineralogy and is generally for sophomore or junior level students.
Skills and concepts that students must have mastered
The background students require to complete this exercise includes an introduction to symmetry and to the crystal systems. If the fourth activity is assigned, introduction to Miller indicies, forms and stereographic projection is also needed. I have not tried this exercise exclusively as a "discovery" exercise in which students have no prior introduction to symmetry and crystal systems, although I think this approach might also be possible.
How the activity is situated in the course
This activity is a stand-alone exercise, but is part of a larger volume of classroom and laboratory activities from "Teaching Mineralogy," a workbook published by the Mineralogical Society of America, Brady, J., Mogk, D. W., and Perkins, D., (editors), 1997,406 pp.
Goals
Content/concepts goals for this activity
This laboratory exercise is designed to achieve three objectives:
- to fix in students' minds the essential symmetry content of the six crystal systems;
- to help students visualize the relation between three-dimensional objects and their two-dimensional representations; and
- to help students understand the relationships between the six crystal systems.
Higher order thinking skills goals for this activity
This activity helps students to develop computer models of crystallographic data.
Other skills goals for this activity
This activity aids in student collaboration and group work.
Description of the activity/assignment
This laboratory exercise involves construction of physical and computer models of crystals based on a description of their symmetry. The purpose of the exercise is to help you visualize symmetry in two and three dimensions, and to help you explore the relationships between the different crystal systems. It is a problem-solving exercise: the morphology of the crystal is described in simple terms, and both physical and computer models should meet the requirements of these descriptions. Because the physical models may be used in other laboratory exercises, they should be large enough and precise enough for measurement, and durable enough to take handling.
Determining whether students have met the goals
Each group will be assigned a grade for models and graphics. This group grade will be 50% of the grade for the exercise. Grades for the essay will be the other 50% of the grade.
More information about assessment tools and techniques.Teaching materials and tips
Other Materials
- Assignment description, hand outs, and instructor's notes. FILE 1 OF 2 (Microsoft Word 19kB Apr27 08)
- Assignment description, hand outs, and instructor's notes. FILE 2 OF 2 (Microsoft Word 18kB Apr27 08)
- Assignment description, hand outs, and instructor's notes. (Acrobat (PDF) 1.3MB Apr27 08)
Supporting references/URLs
Brady, J., Mogk, D. W., and Perkins, D., (editors), 1997, Teaching Mineralogy, a workbook published by the Mineralogical Society of America, 406 pp.
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Mineralogical Society of America - become a member today!