\Pyr"ox*ene\, n. [F. pyrox[`e]ne, from Gr. ? fire + ? a
stranger; -- so called because it was supposed to the be a
stranger, or of rare occurrence, in igneous rocks,] (Min.)
A common mineral occurring in monoclinic crystals, with a
prismatic angle of nearly 90[deg], and also in massive forms
which are often laminated. It varies in color from white to
dark green and black, and includes many varieties differing
in color and composition, as diopside, malacolite, salite,
coccolite, augite, etc. They are all silicates of lime and
magnesia with sometimes alumina and iron. Pyroxene is an
essential constituent of many rocks, especially basic igneous
rocks, as basalt, gabbro, etc.

Note: The pyroxene group contains pyroxene proper, also the
      related orthorhombic species, enstatite, bronzite,
      hypersthene, and various monoclinic and triclinic
      species, as rhodonite, etc.