Enstatite is a common mineral in the pyroxene group, typically found in mafic and ultramafic igneous rocks, as well as in some metamorphic rocks. It is composed of magnesium silicate (MgSiO3) and is important in understanding the mineralogical composition of the Earth’s mantle and the petrogenesis of igneous rocks.
Reference: Deer, W. A., Howie, R. A., & Zussman, J. (2013). “An Introduction to the Rock-Forming Minerals.” The Mineralogical Society.