Orthorhombic crystal system

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, so 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

Name	Primitive (P)	Body-centered (I)	Base-centered (A, B or C)	Face-centered (F)
Pearson symbol	oP	oI	oS	oF
Unit cell

Crystal classes

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

#	Point group					Type (Example)	Space groups
	Name	Schön.	Intl	Orb.	Cox.
16-24	sphenoidal	D2	222	222	[2,2]+	enantiomorphic (epsomite)	P222, P2221, P21212, P212121 C2221, C222 F222 I222, I212121
25-46	pyramidal	C2v	mm2	*22	[2]	polar (hemimorphite, bertrandite)	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]	centrosymmetric (olivine, aragonite, marcasite)	Pmmm, Pnnn, Pccm, Pban, Pmma, Pnna, Pmna, Pcca, Pbam, Pccn, Pbcm, Pnnm, Pmmn, Pbcn, Pbca, Pnma Cmcm, Cmca, 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.