In terms of "where do the electrons come from", an ordinary neutron in free space has a half-life of about 10 minutes, decaying through beta decay which produces a proton, an electron and a neutrino.
That sounds fairly energetic... So after 10min you'd have some odd mix of heavy elements probably approaching a decent fraction of the volume of everest. Half the volume of everest x (densityofgranite / densityoflead)
That kind of expansion rate has to rival any explosion imaginable.
