Oh my goodness. Never, never, never do this. By "this" I mean put halogen lights over or pointing at your mirrors. That is unless you like perpetually dirty looking mirrors.
Mirrors are not perfect. They have imperfections, especially low-quality mirrors. They are cloudy, sometimes scratched, marred. You often can't tell unless you have a halogen light pointing directly at them. The worst part is when you try to clean the halogen-lit mirror. Every little fibre from your cloth shows up, every little smudge - spray as much cleaner as you want, nothing helps.
This again reinforces my point that many designers don't think about maintenance during the design phase.
Don't buy these for your home...