757
And here you ever seen PIRIT?

Pyrite - iron disulphide FeS2, the most common in the earth's crust sulfide.
Pyrite crystallizes in the cubic system. Crystals in the form of a cube, pentagon-dodecahedron, at least - the octahedron.
I touched today is such a die and wondered for a long time that he grew up a perfect cube. Just some magic))