The Use of Natural Crystals in the Study of Crystallography

Roger Steinberg
,
Del Mar College
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Summary

I use single, euhedral, natural crystals of minerals extensively when teaching basic concepts of crystallogtaphy. In my Mineralogy course, I use single, well-formed crystals in all aspects of basic crystallography inlcuding measurement of interfacial angles, determination of symmetry elements, recognition of crystal system and class, determination of forms, stereographic projections and stereograms, recognition of common twins and pseudomorphs, and even SHAPE plots - these are just some of the possibilities.

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Context

Audience

This activity is designed for a sophomore or junior level required course in mineralogy; many of the mineralogy students I teach are environmental science and education majors with a few geology majors usually interested in working in the oil fields.

Skills and concepts that students must have mastered

Students should have a basic understanding of mineralogy and crystallography, including crystal symmetry and groups; this exercise should strengthen this knowledge base.

How the activity is situated in the course

This is a stand-alone exercise.

Goals

Content/concepts goals for this activity

This activity is designed to strengthen students' comprehension of crystallography using real minerals. It can be used to aid students in measurement of interfacial angles, determine symmetry elements, recognize crystal system and class, determine forms, stereographic projections and stereograms, and in recognizing common twins and pseudomorphs.

Higher order thinking skills goals for this activity

This activity involves analyzing hand samples for crystallography.

Other skills goals for this activity

This activity may involve writing skills and working in groups.

Description of the activity/assignment

I use single, euhedral, natural crystals of minerals extensively when teaching basic concepts of crystallogtaphy. Wooden or paper models, showy museum-quality crystal clusters, colorful pictures in a book, or even computer images simply cannot compete with the beauty and awe-inspiring mystery and educational value of genuine, individual mineral crystals when held in your (or your students') hands.
In my Mineralogy course, I use single, well-formed crystals in all aspects of basic crystallography inlcuding measurement of interfacial angles, determination of symmetry elements, recognition of crystal system and class, determination of forms, stereographic projections and stereograms, recognition of common twins and pseudomorphs, and even SHAPE plots - these are just some of the possibilities.

Determining whether students have met the goals

Students have met the goals of this activity if they are able to answer the questions provided in the activity description/assignment download provided below.

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