About 4,000,000 tons of sulfur are recovered in the United States each year from natural gas, petroleum refinery gases, pyrites, and smelter gases from the processing of copper, zinc, and lead ores. Monoclinic sulfur is obtained when liquid sulfur is cooled slowly. It consists of long, needlelike crystals. It is stable between 96 degrees celcius and 119 degrees celcius. At room temperature, it changes slowly to the rhombic form. When hot molten sulfur is cooled, suddenly, it forms a soft, sticky, elastic, noncrystalline mass called amorphous, or plastic sulfur. Although the rhombic and monoclinic forms are highly soluble in carbon disulfide, amorphous sulfur is not. Hydrogen sulfide is produced naturally be the decay of organic substances containing sulfur and is often present in vapours from volcanoes and mineral sulfide are obtained in the removal of sulfur from petroleum.
Sulfur forms a wide variety of compounds with halogen elements. In combination with chlorine, it yields sulfur chlorides such as disulfur dichloride with fluorine, sulfur fluorides, the most useful of which is sulfur hexaf luoride.