From Online Dictionary of Crystallography
Revision as of 10:34, 8 July 2017 by BrianMcMahon (Added couple of links to "See also")
Ogdoédrie (Fr). Ogdoedria (Sp). Ogdoedria (It). 八面像 (Ja)
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).