Sulfur is an elemental mineral with an atomic number of 16. It is abundant, tasteless and it is a multivalent non-metal. It usually appears as a yellowish pigment. It forms in small, lemon-yellow crystals with the crystal habit of orthorhombic. Broken sulfur gives off an odor of rotten eggs. Sulfur was used by the ancient Chinese and mixed with potassium nitrate to form a compound known today as gunpowder. It was discovered and used by alchemists in attempts to turn items to gold.