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Ogdohedry

From Online Dictionary of Crystallography

Revision as of 10:25, 16 May 2017 by BrianMcMahon (talk | contribs) (Style edits to align with printed edition)

Ogdoédrie (Fr). Ogdoedria (Sp). Ogdoedria (It). 八面像 (Ja)


Definition

The point group of a crystal is called ogdohedry if it is a subgroup of index 8 of the point group of its lattice.

In three-dimensional space there is only one ogdohedry: it corresponds to the geometric crystal class 3 of crystals belonging to the hexagonal lattice system (in the case of rhombohedral crystals, it corresponds instead to a tetartohedry).

See also

  • Chapter 3.2.1 of International Tables for Crystallography, Volume A, 6th edition