Because we're working with AC, we need a small skin effect, which is given by the inverse square root of [pifrequencypermeability*conductivity]. It's permeability that's going to be the deciding factor here, because all metals have reasonably similar conductivity but ferromagnetic materials have four orders of magnitude higher permeability.

This also means that steel which is not ferromagnetic will not work on an induction stovetop. The stove will detect it and the chip will reject the pan to prevent damage to the coils.