(Science: chemical) 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 colour from white to dark green and black, and includes many varieties differing in colour 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.
Origin: F. Pyroxene, from Gr. Fire _ a stranger; so called because it was supposed to the be a stranger, or of rare occurrence, in igneous rocks.