sulphur (symbol S) Nonmetallic element in group VI of the periodic table, known since pre-history (the biblical brimstone). Essential to animal and plant life, it may occur naturally as a free element or in sulphide minerals such as galena and iron pyrites, or in sulphate minerals such as gypsum. The main commercial source is native (free) sulphur, extracted by the Frasch process. It is used in the vulcanization of rubber and in the manufacture of drugs, matches, dyes, fungicides, insecticides, and fertilizers. Properties: at.no. 16; r.a.m. 32.064; r.d. 2.07; m.p. 112.8°C (235°F); b.p. 444.7°C (832.5°F). Most common isotope S³² (95.1%).

Frasch process See sulphur Named after the German-born chemist Herman Frasch, the process was first put to practical use in Louisiana and made the USA independent of imported sulphur.