Mineral Species: Marcasite

Chemical Formula: FeS2

Chemical Name: Iron Sulfide

Mineral Class: Sulfide

Mineral Notes: Marcasitw is a mineral whose name is derived from Arabic for Pyrite because the two minerals were often confused due to their similarities. Indeed Marcasite is a polymorph of Pyrite, which means that it has identical chemical composition but a different crystalline structure. The Marcasite/Pyrite pair is probably the most famous polymorph pair apart from Diamond/Graphite.