An orthorhombic mineral series, 8((Mg,Fe)₂Si₂O₆) ; pyroxene group, intermediate between enstatite and ferrosilite; prismatic cleavage; a common rock-forming mineral in intermediate to mafic igneous rocks and high-grade metamorphosed iron formations of the Lake Superior type; abundant in host rocks of copper-nickel ores of Sudbury, ON, Canada, and of chromite deposits of the Bushveld complex, South Africa.