Ogdohedry
From Online Dictionary of Crystallography
Revision as of 18:53, 2 March 2007 by MassimoNespolo (talk | contribs)
Revision as of 18:53, 2 March 2007 by MassimoNespolo (talk | contribs)
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 the 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 case rhombohedral crystals, it corresponds instead to a tetartohedry).
See also
Section 9.1 of International Tables of Crystallography, Volume A