Iron Pyrite, Octahedral, Pyrite commonly forms cubes, octahedrons, pyritohedrons or some combinations of these forms. All pyrite is FeS2 with the same internal arrangement of iron and sulfur atoms. Why then, should pyrite crystals take on different shapes? All these forms reflect the same internal atomic symmetry, so the reasons must involve the conditions under which the pyrite forms. These are such things as temperature, pressure, acidity, and the composition of the fluids from which the pyrite grew.

The Iron Pyrite in this collection was sourced from many locations, under different conditions giving us the different shapes and formations you see before you.  

In geometry, an octahedron is a polyhedron with eight faces.  The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex.