Technically speaking, sulfur (note that it does NOT begin with a capital unless it is the first word in a sentence) is correct. 'Sulfur' is the international chemical term recommended by IUPAC...
It is used in some soaps, makes gunpowder ,used on matches, in fertilizers ,fungicides, and pesticides. Only sulfur that isn't pure has a rotten egg smell, and those that do smell has only a hint of...