Brauns, R. (Reinhard), 1861-1937, Spencer, Leonard James, 1870- · Esslingen a. N. : J. F. Schreiber · leaf 35
that corresponding to each face there is on the opposite side of the crystal, a parallel face similar in character to the first. Such crystals are said to possess a centre of symmetry. In some crystals the only element of symmetry is a centre of symmetry; in others there may be one plane of… … association of nine planes of symmetry, thirteen axes of symmetry, and a centre of symmetry. Other crystals lie between these extremes in the degree of symmetry which they exhibit. In this way all crystals may be divided into thirty-two classes, each having a different degree of symmetry. It is…
Mineralogy
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