Sulfur is a relatively abundant non-metallic element (atomic number 16), also known as brimstone. Surprisingly, pure sulfur is a tasteless and odorless multivalent substance, best known in yellow crystals. However, when combined with hydrogen or oxygen (as in hydrogen sulfide or sulfur dioxide), we observe the "rotten egg" smell that is associated with sulfur.
Sulfur is sometimes spelled sulphur. It occurs in many sulphide and sulphate minerals.