Pyrite after pyrrhotite, with flattened rhombohedral calcite, from Trepca Mine Complex, Mitrovica, Kosovo.Calcite fluorescent with 365nm long wave UV light.Size: 45 x 36 x 35 mm. 32 grams.Pyrite after pyrrhotite pseudomorph is a mineral specimen that shows the replacement of pyrrhotite by pyrite, preserving the original shape and structure of the former. Pyrrhotite is an iron sulfide mineral that often forms hexagonal or pentagonal crystals, sometimes resembling roses. Pyrite is another iron sul