Dims: 4.75" x 4.25" x 1.50"
This is our "Mystery Piece." I've got the location of this specimen narrowed to two localities: either Missouri or Peru. I personally think it's Missouri. Also, we're not sure if the specimen was initially Pyrite when it formed, or if it started out as a botryoidal form of Marcasite and then pseudomorphed. I think that it started out as Marcasite, personally, which would support my Missouri location theory. Either way, it's an odd formation that is almost amusing, making me conjure up the idea of a pyritized "Coprolite," or "fossil poop."