Last Update 21/ 02/ 2004
in English/ in Esperanto/ in Portuguese
Click on any of the five buttons on the right side of the figure to operate one of the symmetry classes of the rhombohedral crystal system up on a face pole in stereographic projection. Among the 32 point groups of symmetry elements in crystallography, the button on class 3 has only a 3-fold axis, the second operates an improper 3-fold axis, the both next buttons operate a mirror plane containing an axis and the last a 3-fold axis and a 2-fold axis.
A click on the circle will clear the figure and select a new face pole.
Exercises
1) At what angle the 3-fold axis and the 2-fold axis intersects in class 32?
2) How many 2-fold axes are observed in class 32?
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