Difference between revisions of "Ogdohedry"
From Online Dictionary of Crystallography
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== Definition == | == 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. | + | 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]]). | 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]]). | ||
Revision as of 10:08, 9 April 2007
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