Jademonkey

Thanks, but I knew that, I wanted to know why there was alot of pyrite in fossil beds (my fault I should of worded the question a little bit clearer).

Just recently I have been spending alot of my time collecting fossils and I've noticed that where fossil beds made up of organic material there is a lot of iron pyrite. Some of the fossils from these beds are pyrite as well but not all, why is this and why is there large deposits of iron in these beds?