Pyrite, Hematite - Rio Mine (Rio Marina Mine), Italy - 55 x 52 mm
Mineral: Pyrite, Hematite
Locality: Rio Mine (Rio Marina Mine), Valle Giove stope, Rio Marina, Elba Island, Livorno Province, Tuscany, Italy
Dimensions: 55 x 52 mm

Description: It looks like an octahedron, but it is actually a pseudoicosahedron (5 contiguous triangular faces: 3 equilateral and 3 isosceles).