Feldspar
Feldspar is a principal constituent of many rocks. Clays seem, very generally, to have resulted, at least in great part, from its decomposition. Kaolin, or China clay, is considered to be decomposed feldspar. See KAOLIN; ROCKS.
Twelve hundred entries from the golden age of cast metal — how bells are founded, why brass is not bronze, what a cupola melts and a core withstands — by Simpson Bolland, the trade's great teacher.
Feldspar is a principal constituent of many rocks. Clays seem, very generally, to have resulted, at least in great part, from its decomposition. Kaolin, or China clay, is considered to be decomposed feldspar. See KAOLIN; ROCKS.