A dead-burned refractory magnesia composition suitable for use in the manufacture of high hot strength magnesia refractories comprises at least 95% by weight MgO, less than 0.4% by weight of silica, an amount of lime greater than (2S + 0.3)% by weight, where S is the percentage by weight of silica, the weight ratio of lime to silica in the composition being greater than 3:1, and boron in an amount of less than 0.25% by weight expressed as B.sub.2 O.sub.3.
Disclosed herein are a refractory material of high-purity electrofused magnesia clinker having good resistance to corrosion by slag, especially the slag with a high iron content, at high temperatures under an oxidative environment, and a burned or unburned refractory brick made of such refractory material of high corrosion resistance, which is superior in corrosion resistance as well as spalling resistance. The refractory material comprises more than 10 wt. % of electrofused magnesia clinker containing 98.0 to 99.8 wt. % of MgO, less than 0.05 wt. % of SiO.sub.2, and 0.1 to 2.0 wt. % of CaO. It may be in the form of burned or unburned or prepared unshaped refractories.
