Most enstatite chondrites have experienced thermal metamorphism on the parent asteroids. At higher metamorphic grades, anthophyllite, enstatite, olivine and diopside dominate as the rock mass dehydrates. Chemically, enstatite chondrites are very low in refractory lithophile elements. Sanidine phenocrysts and augite (or enstatite) are found in some samples. Orthopyroxene near pure enstatite in composition occurs in some metamorphosed serpentines. Wollastonite (CaSiO) and enstatite (MgSiO) are examples of silicate-based minerals. The meteorite consists largely of the mineral enstatite, and is of the rare Diogenite type. Pure synthetic magnesium majorite (MgSiO) is polymorphous with enstatite, and akimotoite. They are primarily composed of the orthopyroxene enstatite, and are often called enstatite achondrites. Enstatite is a common mineral in meteorites. This material is termed bronzite, although it is more correctly called altered enstatite. An emerald-green variety of enstatite is called chrome-enstatite and is cut as a gemstone. E-type asteroids are asteroids thought to have enstatite (MgSiO) achondrite surfaces. Enstatite melts congruently between pressures of 2.5 and 5.5 kilobars.