(This is not really an advanced question, but one for physicists advanced in this science, which I am not.) In fairly recent investigation, the signature of Dirac monopoles was observed in spin ice. Say I possessed a consistent mathematical development allowing for both magnetic monopoles and a 4-vector electromagnetic potential cast in microscopic form. Classically, it works nicely, and the monopoles can be gauged-away in vacuum. I say this just for background; I'm not advancing a theory in these forums. 1) For solid state physicists, would it be more useful if I reformulated in macroscopic form? 2) I know virtually nothing about spin-ice. Should I be concerned over non-isotropic permeability and/or permittivity? I would far prefer not to use non-isotropic formulations if applicable to materials that have shown evidence of Dirac strings.