A pyroxene close in composition to magnesium metasilicate (MgSiO₃). Like other pyroxenes, enstatite is typified by a pair of nearly perpendicular cleavages, both of which are parallel to the elongate dimension of the characteristically prismatic crystals. These cleavages reflect an atomic structure dominated by unbroken, parallel, linear chains of SiO₄ tetrahedra (silicon atoms surrounded by four oxygens).