High Quality Content by WIKIPEDIA articles! In geometry, a pyritohedron is an irregular dodecahedron with pyritohedral (Th) symmetry. Like the regular dodecahedron, it has twelve identical pentagonal faces, with three meeting in each of the 20 vertices. However, the pentagons are not regular, and the structure has no five-fold symmetry axes. Its 30 edges are divided into two sets - containing 24 and 6 edges of the same length. Although regular dodecahedra do not exist in crystals, the distorted pyritohedron form occurs in the crystal pyrite, and it may be an inspiration for the discovery of the the regular Platonic solid form.

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