noun. Any of a group of crystalline silicate minerals common in igneous and metamorphic rocks and containing two metallic oxides, as of magnesium, iron, calcium, sodium, or aluminum.

noun. An important mineral species, embracing many varieties differing in appearance and chemical composition.

noun. A common mineral occurring in monoclinic crystals, with a prismatic angle of nearly 90°, 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.

noun. Any of a group of crystalline minerals containing silicates of iron, magnesium and calcium.

noun. any of a group of crystalline silicate mineral common in igneous and metamorphic rocks

"The presence in the meteorites of micrometer-sized crystals of a mineral called pyroxene indicates that these rocks formed at a relatively shallow depth, between 15 and 20 meters, says Day - additional evidence that the meteorites are fragments of an ancient asteroid crust."

mineral