It is produced by fusion in the electric are furnace with high temperature with superior magnesite as raw materials.Periclase develops completely and its crystal body is big,with high combination rate,firm and tight structure,good refuses resistance and stable and good high temperature volume.It is good raw materials to produce Magnesia carbon bricks,high-class basic bricks and unshaped refractory materials.Crades are calssified according to MgO content95%-98%