As Orodruin says, a black hole is not just a star that's stopped fusing. That leads to a (super)nova and some larger stars collapse into black holes, but a black hole is very different from a star.
All sorts of heavy elements get produced in supernovae. I'm sure they get produced in tiny quantities in during normal operation, but it's an energy absorber not a producer so the process isn't self-sustaining. That's why you don't see iron-burning stars - it's the fusion equivalent of trying to light ashes.
As to why iron doesn't produce energy, the binding energy per nucleon changes as the atomic mass rises. It first increases, meaning that one helium atom needs slightly more energy to separate it into four nucleons than two deuterium atoms do. So two deuterium atoms combining into one helium leaves a bit of energy over.
But that stops at iron, and then the trend reverses. Very heavy elements need less energy to separate into components than smaller ones, so combining smaller atoms costs energy. Splitting large atoms into smaller ones (down to iron) releases energy - which is nuclear fission.
The underlying reason for the differences in binding energy is the balance between the strong force holding the nucleus together and increasing amounts of electrostatic repulsion between the increasing number of protons.