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.

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

simple orthorhombic	base-centered orthorhombic	body-centered orthorhombic	face-centered orthorhombic

The point groups (or crystal classes) that fall under this crystal system are listed below, followed by their representations in International {Hermann-Mauguin) notation and Schoenflies notation, and mineral examples.

Name	International	Schoenflies	Example
orthorhombic bipyramidal	$frac2mmm$	D2h	sulfur, olivine, aragonite
orthorhombic pyramidal	$2\; mm$	C2v	hemimorphite, bertrandite
orthorhombic sphenoidal	$222$	D2	epsomite

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