Abstract: This disclosure concerns a thermo-chemical bonded refractory product which comprises inactive refractory grains bonded together by mullite. The refractory is emplaced in a furnace or other pyro-processing unit by pressing, ramming, gunning, casting, etc. The refractory product is made by mixing inactive refractory grains with a mixture of zircon and alumina powders and a small amount of an alkaline earth oxide catalyst. The catalyst breaks the zircon down into ZrO.sub.2 and SiO.sub.2 at relatively low temperatures. The SiO.sub.2 thus liberated is unusually reactive and reacts with the alumina to form mullite and the ZrO.sub.2 adsorbs the alkaline earth oxide.