Geometric crystal class

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(French: Classes cristallines géométriques; German: Geometrische Kristall Klasse; Spanish: Clases cristallinas geométricas.)

Definition

Geometric crystal classes (or simply 'crystal classes') classify the symmetry groups of the external shape of macroscopic crystals, namely according to the morphological symmetry. There are 10 two-dimensional geometric crystal classes and 32 three-dimensional geometric crystal classes, in one to one correspondence with the 10 and 32 point groups in E2 and E3, respectively.

See also

Section 8.2.4 of International Tables of Crystallography, Volume A