Magnesium oxide (MgO) crucible have found application in the superalloy industry, nuclear industry and chemicals industry where corrosion resistance is required. Manufacture is by firing isostatically pressed or slip cast shapes made from fused magnesia. Various purity grades are commercially available. Additives are employed to promote sintering or restrict crystal growth. These range from clay to yttria and alumina depending on application. Crucibles with stability of 2400oC in air, 1700oC in reducing atmospheres, 1600oC in vacuum and 1400oC in hydrogen have been reported in the literature.