Pyrite after Anhydrite

Quite unusual and interesting specimen showing golden sparkly crystallized pyrite, these forming sharp casts after now gone bladed crystals of anhydrite. The find was purportedly in 1992. This discovery in mentioned in the 1993 Mineralogical Record, V. 24, # 1, p. 48. This mine is famous for its sulfides, mainly Galena, Sphalerite and Chalcopyrite, but Pyrite is not terribly common, especially a piece like this in which matte lustered tiny modified pyrite cubes have formed pseudomorphs after preexisting crystals of prismatic Anhydrite.

Locality: Milliken (Sweetwater) Mine, South End, Reynolds County, Missouri

Composition: iron sulfide