  The theory for disordered itinerant ferromagnets developed in a previous
paper is used to construct a simple effective field theory that is capable of
describing the quantum phase transition from a ferromagnetic metal to a
ferromagnetic insulator. It is shown that this transition is in the same
universality class as the one from a paramagnetic metal to a paramagnetic
insulator in the presence of an external magnetic field, and that strong
corrections to scaling exist in this universality class. The experimental
consequences of these results are discussed.
