Triclinic crystal system

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In crystallography, the triclinic crystal system is one of the 7 lattice point groups. A crystal system is described by three basis vectors. In the triclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. In addition, all three vectors are not mutually orthogonal.  

The triclinic lattice is the least symmetric of the 14 three-dimensional Bravais lattices. It has (itself) the minimum symmetry all lattices have: points of inversion at each lattice point and at 7 more points for each lattice point: at the midpoints of the edges and the faces, and at the center points. It is the only lattice type that itself has no mirror planes.

The point groups that fall under this crystal system are listed below, followed by their representations in international notation and Schoenflies notation.

Name	International	Schoenflies
triclinic normal		Ci (also denoted by S2)
triclinic hemihedral	1	C1

With each only one space group is associated.

Mineral examples include plagioclase, microcline, rhodonite, turquoise, wollastonite and amblygonite, all in triclinic normal (bar 1).

See also

• Crystal structure

References

• Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., pp. 64 - 65, ISBN 0-471-80580-7