External Symmetry of Crystals, 32 Crystal Classes

Stephen Nelson, Tulane University

This site is a lecture by Dr. Stephen Nelson from Tulane University that explores the 32 possible combinations of symmetry operations that define the external symmetry of crystals. The lecture defines the six crystal systems (triclinic, monoclinic, orthorhombic, tetragonal, hexagonal, and isometric) and explains the derivation of the Hermann-Mauguin symbols (also called the international symbols) used to describe the crystal classes from the symmetry content. Tables and illustrations accompany the text.

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Part of the Cutting Edge collection. The NAGT/DLESE On the Cutting Edge project helps geoscience faculty stay up-to-date with both geoscience research and teaching methods.

Cutting Edge

Subject: Geoscience:Geology:Geochemistry, Mineralogy:Crystallography
Resource Type: Audio/Visual:Images/Illustrations, Course Information:Course Site:Course Notes
Grade Level: College Upper (15-16)
Course Type: Upper Level:Mineralogy
Topics: Solid Earth:Geochemistry, Mineralogy:Crystallography, Chemistry/Physics/Mathematics, Solid Earth
Theme: Teach the Earth:Course Topics:Mineralogy, Geochemistry