# Geometric crystal class

### From Online Dictionary of Crystallography

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- | <font color="blue"> | + | <font color="blue">Classe cristalline géométrique</font> (''Fr''). <font color="red">Geometrische Kristallklasse</font> (''Ge''). <font color="black">Classe cristallina geometrica</font> (''It''). <font color="purple">幾何的結晶類</font> (''Ja''). <font color="green">Clase cristalina geométrica</font> (''Sp''). |

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== Definition == | == 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 ''E''<sup>2</sup> and ''E''<sup>3</sup>, respectively. | + | '''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 ''E''<sup>2</sup> and ''E''<sup>3</sup>, respectively. |

== See also == | == See also == | ||

*[[Arithmetic crystal class]] | *[[Arithmetic crystal class]] | ||

- | * | + | *Chapter 1.3.4.2 of ''International Tables for Crystallography, Volume A'', 6th edition |

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[[Category:Fundamental crystallography]] | [[Category:Fundamental crystallography]] |

## Latest revision as of 14:38, 13 November 2017

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

## 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 *E*^{2} and *E*^{3}, respectively.

## See also

- Arithmetic crystal class
- Chapter 1.3.4.2 of
*International Tables for Crystallography, Volume A*, 6th edition