The Orthorhombic reference article from the English Wikipedia on 24-Jul-2004
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Orthorhombic

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In crystallography, the orthorhombic crystal system is one of the 7 lattice point groups. Orthorhombic lattices result from stretching a cubic lattice along two of its lattice vectors by two different factors, resulting in a rectangular prism with a rectangular base (a by b, which is different from a) and height (c, which is different from a and b). 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 notation and Schoenflies notation, and mineral examples.

name international Schoenflies example
orthorhombic bipyramidal D2h sulfur
orthorhombic pyramidal C2v
orthorhombic sphenoidal D2