Kaolin
A pure white clay resulting from the decomposition of feldspar in granitic rocks. The materials employed by the Chinese for the manufacture of porcelain are known to be kaolin, petuntze, or quartz reduced to a fine powder; and the ashes of fern, which contain potassic carbonate. Kaolin is used extensively for the manufacture of clay crucibles for steel melting, being mixed with equal quantities of Stourbridge clay and some old pot and coke-dust. See CRUCIBLE; FELDSPAR.