Marcasite looks like and even has the same chemical formula as pyrite, or “fool’s gold,” but it is a separate and much less common mineral. Marcasite is paler in color, becomes darker upon oxidation, and is more apt to crumble than pyrite. Its tendency to break down makes it a poor choice for use in jewelry, so pyrite is actually used in its stead but is referred to as “marcasite” in this context. What is “pyrite decay,” and how does it affect marcasite? Discuss