A product, manufactured by the action of heat on earthy raw materials, in which silicon and its oxide and complex compounds known as silicates occupy a predominant position (American Ceramic Society). The chief groups of the ceramics industry are as follows: (1) structural clay products (brick, tile, terra-cotta, glazed architectural brick); (2) whitewares (dinnerware, chemical and electrical porcelain, e.g., spark plugs, sanitary ware, floor tile); (3) glass products of all types; (4) porcelain enamels; (5) refractories (materials that withstand high temperatures); (6) Portland cement, lime, plaster, and gypsum products; (7) abrasive materials such as fused alumina, silicon carbide, and related products; (8) aluminum silicate fibers. A wide range of ceramics are available as ultrafine particles (10–150 microns), and ceramic foams are offered commercially.