Triclinic crystal system

Short description: One of the seven crystal systems

An example of the triclinic crystals, microcline

thumb|180px|Triclinic (a ≠ b ≠ c and α ≠ β ≠ γ )

In crystallography, the triclinic (or anorthic) crystal system is one of the 7 crystal systems. 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, the angles between these vectors must all be different and may not include 90°.

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.

Crystal classes

The triclinic crystal system class names, examples, Schönflies notation, Hermann-Mauguin notation, point groups, International Tables for Crystallography space group number,^[1] orbifold, type, and space groups are listed in the table below. There are a total of 2 space groups.

#	Point group					Type	Example	Space group
#	Name^[2]	Schönflies	Intl	orbifold	Coxeter	Type	Example	Space group
1	Pedial	C₁	1	11	[ ]⁺	enantiomorphic polar	Tantite	P1
2	Pinacoidal	C_i (S₂)	1	1×	[2⁺,2⁺]	centrosymmetric	Wollastonite	P1

With each only one space group is associated. Pinacoidal is also known as triclinic normal. Pedial is also triclinic hemihedral.

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

References

↑ Prince, E., ed (2006). International Tables for Crystallography. International Union of Crystallography. doi:10.1107/97809553602060000001. ISBN 978-1-4020-4969-9.
↑ "The 32 crystal classes". https://www.tulane.edu/~sanelson/eens211/32crystalclass.htm.

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

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[ITC-1] Prince, E., ed (2006). International Tables for Crystallography. International Union of Crystallography. doi:10.1107/97809553602060000001. ISBN 978-1-4020-4969-9.

[2] "The 32 crystal classes". https://www.tulane.edu/~sanelson/eens211/32crystalclass.htm.

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Triclinic crystal system

Topic: Physics

Contents

Crystal classes

See also

References

External links