Locality: Missouri, USA
Size: 34 mm x 34 mm x 28 mm (1.3 in. x 1.3 in. x 1.1 in.)
Weight: 96 g (3.4 oz.)
Partial cube of limonite pseudomorph after pyrite. This piece has sharp edges and smooth surfaces.
A pseudomorph forms when a mineral (limonite, in this case) replaces another (pyrite), while retaining the form of the original mineral.