Sulfur's atomic number is 16 and its symbol is S. Elemental sulfur is a nonmetal brittle crystal that is solid at room temperature. Sulfur is an essential element for all forms of life usually in the form of amino acids, keratin, biotin, and thiamine. Sulfur has been known since ancient times and is referred to in early literature as “brimstone” because of the distinctive rancid smell that is produced when lightning strikes a rock and vaporizes the sulfur present in the rock. When sulfur is burned it melts into a blood-red liquid and emits a blue flame. Elemental sulfur can be found near hot springs and volcanoes. Most of the sulfur that is currently being mined comes from areas of the world that are along the Pacific Ring of Fire such as Indonesia, Chile, and Japan. Elemental sulfur is used in black gunpowder, matches, and fireworks; in the vulcanization of rubber; as a fungicide, insecticide, and fumigant; in the manufacture of phosphate fertilizers; and in the treatment of certain skin diseases.