Sulphur is a yellow, brittle, crystalline nonmetallic element (symbol S). It occurs naturally in native form, and in sulphide ores such as galena and zinc blende. Native sulphur results from sublimation of sulphur gas from volcanoes and fumaroles, from the action of bacteria on gypsum and from the oxidation of metallic sulphides. Its main use is in the production of sulphuric acid. Sulphur is also found extensively in the body, as a component of proteins and in keratin (nails, hair, etc,).