Electrofused magnesia is made of fine Grade A natural magnesite or high purity light burning magnesia particles by melting in an electric arc furnace. The product has high purity, large crystalline particles, compact structure, strong slag resistance, good thermal shock stability, is an excellent high temperature electrical insulation material, is also an important raw material for the production of high-grade magnesia brick, magnesia carbon brick and amorphous refractory materials.