Steven Dutch, Professor Emeritus, Natural and Applied Sciences, University of Wisconsin - Green Bay
Technically, the unit cells of hexagonal and rhombohedral crystals are 60-120 prisms. However, that representation would result in models lacking 3- or 6-fold symmetry. Since hexagonal and rhombohedral unit cells can have any of three equivalent orientations, the best approach is to build models of triangular prisms. After all, the unit cell is an abstraction, not a physically real box.
This is how Rene Hauy deduced that minerals were made up of fundamental units.
Created 18 Sept. 1997, Last Update 10 June 2020
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