This is a Pyrite on Dolomite Mineral Specimen Sulfide.  It weighs 2 oz.  This was found in the Homestake Mine Dumpsite in Lead, SD.  It is thin and wavy.  It looks even better in real life then any picture could have perceived it.   It is a very solid specimen and would take alot of abuse to damage it.  It has very very nice quality pyrite crystals laying on beds of Dolomite.