Geometric crystal class
From Online Dictionary of Crystallography
Revision as of 20:31, 26 April 2016 by MassimoNespolo (colon instead of period)
Classe cristalline géométrique (Fr); Geometrische Kristallklasse (Ge); Clase cristallina geométrica (Sp); Classe cristallina geometrica (It); 幾何的結晶類 (Ja).
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.
The Japanese term commonly used to indicate a crystal class is 晶族 which however, as pointed out by Matsumoto (1977), is not an appropriate translation in that the character 族 is more suitable to indicate a crystal family. According to this author, a better translation of crystal class is 結晶類, which is therefore adopted in this dictionary.
- Arithmetic crystal class
- Section 8.2.4 of International Tables for Crystallography, Volume A
- Matsumoto, T. (1977). J. Miner. Soc. Japan, 13, 247-289.