Four [[Axis|axes]] of [[symmetry]]: three, of equal length, lie in a plane at 120°; the fourth axis is longer or shorter and is at [[right angle]]s to the others.
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#REDIRECT [[Hexagonal system]]
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[[Crystals]] are generally [[prismatic]] or [[columnar]], with a rounded [[triangle|triangular]] or [[hexagon]]al cross section; characteristic forms are three- or six-sided [[prism]]s, [[pyramid]]s, and [[rhombohedron]]s. The very similar ''[[trigonal system]]'' is often included within the hexagonal system. Chesterman, pp. 33-34
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==Sources==
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*Chesterman, Charles W. ''The Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf: New York (1987)