Sulfur in rocks has given us some clues about the development of the Earth’s atmosphere. Rocks older than approx. 2.1 billion contain only traces of sulfates and sulfites. Those younger than 2.1 billion years have much much larger amounts of sulfates and sulfites. (Why do we see this change?)
The Earths’ core is believed to be 5% Sulfur and we also see it on Io, a moon of Jupiter where the planets surface has been covered with the element.
