Kyanite, andalusite, and sillimanite are anhydrous aluminum silicate minerals that have the same chemical formula, Al203Si02o Related materials include synthetic mullite, dumortierite, and topaz - also classified as aluminum silicates. Calcination of kyanite group minerals yields the refractory material mullite. Synthetic mullite is made by heating mixtures of kaolin and bauxite or silica sand and alumina at high temperatures. All of the kyanite group substances can serve as raw materials for manufacturing high performance, high alumina refractories. Kyanite was produced in 1987 by only one company in the United States, Kyanite Mining Corp. of Dillwyn, VA. US producers of synthetic mullite were C-E Minerals Inc., Americus, GA; Didier Taylor Refractories Corp., Greenup, KY; and Electro Minerals US Inc., Niagara Falls, NY. Although data were not available, production of kyanite and synthetic mullite was estimated to have decreased compared with that of 1986. Reasons for this include competition from a new kyanite producer in Sweden and the closing in late 1986 of the only other domestic kyanite producer, Pasco Mining Inc., in Washington, GA. Kyanite, both raw and calcined, was marketed in sizes ranging from 500 to 45 J.Lm (35 to 325 mesh). End uses were in monolithic refractory applications, such as high temperature mortars or cements, ramming mixes, and castable refractories, or with clays and other ingredients in refractory compositions for items such as kiln furniture. More finely ground material was used in body mixes for sanitary porcelains and wall tile. Although data were not available, it was estimated that 90% of kyanite-synthetic mullite output was used in refractories: 55% for smelting and processing iron and steel, 20% for nonferrous metals, and 15% for glassmaking and ceramics. Nonrefractory uses accounted for the balance. Small, but apparently growing tonnages of andalusite from the Republic of South Africa, have been imported into the United States in recent years. Due to its larger particle size, the mineral is used in refractory brick. Import data for andalusite, obtained from nongovernment sources, were estimated at 2.7 kt (3000 st) in 1985, 4.5 kt (5000 st) in 1986, and 12.7 kt (14,000 st) in 1987. The Republic of South Africa has been the world's largest producer of andalusite. Output was estimated at 180 kt (198,000 st) in 1987. In France, output of andalusite in 1987 was an estimated 51 kt (56,000 st). India produced an estimated 30 kt (33,000 st) of kyanite and 14.5 kt (16,000 st) of sillimanite in 1987, mostly for internal consumption. In 1985, Sweden began producing kyanite. Initial output was estimated to be in the 4.5 to 9 ktla (5000 to 10,000 stpy) range.