Enstatite is a mineral belonging to the pyroxene group, with the chemical formula MgSiO3. It is a common mineral found in igneous and metamorphic rocks, as well as in some meteorites and inclusions in diamonds. Other synonyms for enstatite include hypersthene, ferrosilite, and bronzite. Enstatite is known for its unusual optical properties, including high birefringence and pleochroism. It is also an important component of certain types of refractory materials, as it has excellent resistance to thermal shock and chemical corrosion. In addition, enstatite is sometimes used as a gemstone due to its attractive, greenish-brown color and strong luster.