I cannot recall ever seeing crystals of these two minerals growing together in this way, not just from Mexico, but from anywhere! I have looked long and hard through a loupe at this specimen. It almost looks as though one of the minerals has pseudomorphed crystals of the other, but apparently that is not the case. What has happened is that the crystals of bright silver galena and brassy pyrrhotites grew at the same time, in equal balance, with the hexagonal pyrrhotites and cubic galenas in places interrupting or growing around one another. Here and there, it looks almost as though there are crystals that are partly galena and partly pyrrhotite, and only close inspection shows this not to be true. This is one of those rare and incredibly interesting specimens that you can stare at for a very long time without growing bored.4.0 x 3.2 x 2.5 cm