Geometric crystal class

Classe cristalline géométrique (Fr); Geometrische Kristallklasse (Ge); Clase cristallina geométrica (Sp); Classe cristallina geometrica (It);　幾何的結晶類 (Ja).

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 types of point groups in E² and E³, respectively.

See also

• Arithmetic crystal class
• Section 1.3.4.2 of International Tables for Crystallography, Volume A, 6^th edition