What is sulfur?

A pale yellow nonmetallic element occurring widely in nature in several free and combined allotropic forms. It is used in black gunpowder, rubber vulcanization, the manufacture of insecticides and pharmaceuticals, and in the preparation of sulfur compounds such as hydrogen sulfide and sulfuric acid. Atomic number 16; atomic weight 32.066; melting point (rhombic) 112.8°C, (monoclinic) 119.0°C; boiling point 444.6°C; specific gravity (rhombic) 2.07, (monoclinic) 1.957; valence 2, 4, 6.