Sulfur is found in oxidation states ranging from +6 in SO42− to -2 in sulfides. Thus elemental sulfur can either give or receive electrons depending on its environment. Minerals such as pyrite (FeS2) comprise the original pool of sulfur on earth. Owing to the sulfur cycle, the amount of mobile sulfur has been continuously increasing through volcanic activity as well as weathering of the crust in an oxygenated atmosphere.[1] Earth's main sulfur sink is the oceans as SO2, where it is the major oxidizing agent