# Difference between revisions of "Ogdohedry"

### From Online Dictionary of Crystallography

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− | <font color="blue">Ogdoédrie </font>(''Fr''). < | + | <font color="blue">Ogdoédrie</font> (''Fr''). <font color="red">Ogdoedrie</font> (''Ge''). <font color="black">Ogdoedria</font> (''It''). <font color="purple">八面像</font>(''Ja''). <font color="green">Ogdoedría</font> (''Sp''). |

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

+ | *[[Merohedry]] | ||

+ | *[[Tetartohedry]] | ||

+ | *Chapter 3.2.1 of ''International Tables for Crystallography, Volume A'', 6th edition | ||

− | + | [[Category:Fundamental crystallography]] | |

− | |||

− | |||

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

[[Category:Morphological crystallography]] | [[Category:Morphological crystallography]] |

## Latest revision as of 13:17, 16 November 2017

Ogdoédrie (*Fr*). Ogdoedrie (*Ge*). Ogdoedria (*It*). 八面像(*Ja*). Ogdoedría (*Sp*).

## 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

- Merohedry
- Tetartohedry
- Chapter 3.2.1 of
*International Tables for Crystallography, Volume A*, 6th edition