# Dictionary Definition

trigonal adj : having three-fold symmetry [syn:
rhombohedral]

# User Contributed Dictionary

## English

### Adjective

#### Translations

- Italian: trigono

# Extensive Definition

In crystallography, the
rhombohedral (or trigonal) crystal
system is one of the seven lattice
point groups, named after the two-dimensional rhombus. A crystal system is described by
three basis vectors.
In the rhombohedral system, the crystal is described by vectors of
equal
length, of which all
three are not mutually orthogonal. The rhombohedral
system can be thought of as the cubic system
stretched diagonal
along a body. a = b = c; \alpha = \beta = \gamma \neq 90^\circ. In
some classification schemes, the rhombohedral system is grouped
into a larger hexagonal
system.

There exists only one rhombohedral Bravais
lattice.

## List of particulars

The point groups which fall under this crystal system are listed below, followed by their representations in international notation (Hermann-Mauguin notation) and Schoenflies notation, and example crystals.## See also

## References

- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., pp. 78 - 89, ISBN 0-471-80580-7

trigonal in German: Trigonales
Kristallsystem

trigonal in Basque: Kristal-sistema
erronboedriko

trigonal in Korean: 삼방정계

trigonal in Latvian: Trigonālā singonija

trigonal in Norwegian: Trigonal

trigonal in Polish: Układ trygonalny

trigonal in Russian: Тригональная сингония

trigonal in Slovak: Trigonálna sústava

trigonal in Serbian: Ромбоедарска кристална
система

trigonal in Serbo-Croatian: Romboedarska
kristalna sistema

trigonal in Swedish: Trigonala
kristallsystemet

trigonal in Ukrainian: Тригональна
сингонія

trigonal in Chinese: 三方晶系