Sulfur or sulphur (British English; see spelling below) is a chemical element with symbol S and atomic number 16. It is an abundant, multivalentnon-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellowcrystalline solid when at room temperature. Chemically, sulfur can react as either an oxidant or reducing agent. It oxidizes most metals and severalnonmetals, including carbon, which leads to its negative charge in most organosulfur compounds, but it reduces several strong oxidants, such asoxygen and fluorine. Sulfur occurs naturally as the pure element (native sulfur) and as sulfide and sulfate minerals. Elemental sulfur crystals are commonly sought after by mineral collectors for their distinct, brightly colored polyhedron shapes. Being abundant in native form, sulfur was known in ancient times, mentioned for its uses in ancient India, ancient Greece, China and Egypt. Fumes from burning sulfur were used as fumigants, and sulfur-containing medicinal mixtures were used as balms and antiparasitics. Sulfur is referred to in the Bible as brimstone (burn stone) in English, with this name still used in several nonscientific tomes.[3] It was needed to make the best quality of black powder. In 1777, Antoine Lavoisier helped convince the scientific community that sulfur was a basic element, rather than a compound. Elemental sulfur was once extracted from salt domes where it sometimes occurs in nearly pure form, but this method has been obsolete since the late 20th century. Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas andpetroleum. The element's commercial uses are primarily in fertilizers, because of the relatively high requirement of plants for it, and in the manufacture of sulfuric acid, a primary industrial chemical. Other well-known uses for the element are in matches, insecticides and fungicides. Many sulfur compounds are odoriferous, and the smell of odorized natural gas, skunk scent, grapefruit, and garlic is due to sulfur compounds.Hydrogen sulfide produced by living organisms imparts the characteristic odor to rotting eggs and other biological processes.