- 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.
- An important mineral species, embracing many varieties differing in appearance and chemical composition.
- 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.
- Any of a group of <xref>crystalline</xref> <xref>minerals</xref> containing <xref>silicates</xref> of <xref>iron</xref>, <xref>magnesium</xref> and <xref>calcium</xref>.
- any of a group of crystalline silicate mineral common in igneous and metamorphic rocks