any of a very common group of minerals of many varieties, silicates of magnesium, iron, calcium, and other elements, occurring as important constituents of many kinds of rocks, esp. basic igneous rocks.
py·rox·ene (pī-rŏk'sēn') n. 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.
[French pyroxène : Greek puro-, pyro- + Greek xenos, stranger (originally viewed as a foreign substance when found in igneous rocks); see ghos-ti- in Indo-European roots.] py'rox·en'ic (pī'rŏk-sē'nĭk, -sěn'ĭk) adj.