Orthorhombic crystal system

An example of the orthorhombic crystals, aragonite

In crystallography, the orthorhombic crystal system is one of the seven lattice point groups. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a rectangular base (a by b) and height (c), such that a, b, and c are distinct. All three bases intersect at 90° angles. The three lattice vectors remain mutually orthogonal.

Bravais Lattices

There are four orthorhombic Bravais lattices: simple orthorhombic, body-centered orthorhombic, base-centered orthorhombic, and face-centered orthorhombic.

Orthorhombic Bravais lattices

Primitive	Body-centered	Base-centered	Face-centered

Crystal Classes

The orthorhombic crystal system class names, examples, Schönflies notation, Hermann-Mauguin notation, point groups, International Tables for Crystallography space group number, orbifold, type, and space groups are listed in the table below.

#	Point group					Example	Type	Space groups
	Name	Schönflies	Intl	Orbifold	Coxeter
16-24	sphenoidal	D2	222	222	[2,2]+	epsomite	enantiomorphic	P222, P2221, P21212, P212121, C2221, C222, F222, I222, I212121
25-46	pyramidal	C2v	mm2	*22	[2]	hemimorphite, bertrandite	polar	Pmm2, Pmc21, Pcc2, Pma2, Pca21, Pnc2, Pmn21, Pba2, Pna21, Pnn2, Cmm2, Cmc21, Ccc2, Amm2, Aem2, Ama2,Aea2, Fmm2, Fdd2, Imm2, Iba2, Ima2
47-74	bipyramidal	D2h	mmm	*222	[2,2]	olivine, aragonite, marcasite	centrosymmetric	Pmmm, Pnnn, Pccm, Pban, Pmma, Pnna, Pmna, Pcca, Pbam, Pccn, Pbcm, Pnnm, Pmmn, Pbcn, Pbca, Pnma, Cmcm, Cmce, Cmmm, Cccm, Cmme, Ccce, Fmmm, Fddd, Immm, Ibam, Ibca, Imma

See also

• Crystal structure
• Overview of all space groups

References

• Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., pp. 69 – 73, ISBN 0-471-80580-7