Building Trigonal and Rhombohedral Crystals with Unit Cells
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.
Trigonal Prism
Trigonal Pyramid
Trigonal Dipyramid
Ditrigonal Prism
Ditrigonal Pyramid
Ditrigonal Dipyramid
Trigonal Trapezohedron
Ditrigonal Scalenohedron
This is how Rene Hauy deduced that minerals were made up of fundamental units.
Rhombohedron
Rhombohedron Built With Trigonal Unit Cells
Trigonal Compound Forms
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Created 18 Sept. 1997, Last Update 10 June 2020
Not an official UW-Green Bay site