Ortorombisk

Ortorombisk, or orthorhombic in English, is one of the seven crystal systems used in crystallography. It is defined by three mutually perpendicular crystallographic axes a, b, and c, with a ≠ b ≠ c and all interaxial angles equal to 90 degrees.

In the orthorhombic system, the Bravais lattice is described by three lattice types: primitive (P), base-centered (C), and body-centered (I). The unit cell is a rectangular prism with right angles but unequal edge lengths.

The orthorhombic system exhibits three mutually perpendicular two-fold rotation axes and mirror planes, giving the common point-group symmetry mmm (D2h). Real crystals may display only a subset of these symmetries, depending on the specific mineral or compound.

Many minerals and compounds crystallize in the orthorhombic system; common examples include olivine and aragonite. The system is also encountered in various inorganic solids and ceramics, where its distinct a, b, and c parameters influence crystal habits and properties.

Properties of orthorhombic crystals are anisotropic, meaning their physical properties vary with direction. The three principal axes have different lengths, which affects measurements such as refractive indices, optical birefringence, and cleavage along characteristic planes. Knowledge of the orthorhombic structure aids in mineral identification and in understanding the behavior of materials under different conditions.