There's an almost mythical prohibition against using aluminum foil or aluminium containers in the microwave. Something bad will happen, right? Like the oven will explode!
Actually, aluminum can be used safely in a microwave oven. The key is to keep it away from the oven walls...at least an inch. Aluminum that is too close to the walls can cause electrical sparking which can cause a fire or damage the oven.
But aluminum away from the walls is fine, so much so that the Aluminun Foil Containers Manufacturers Association invented the lovely word tri-ovenable, to indicate that aluminum containers can be used in all three oven types -- conventional, toaster and microwave.
Microwaves don't penetrate aluminum, so remove any aluminum covers. But small cover patches of foil (to prevent foods from heating) or heating in open aluminum containers is fine. Just keep the metal clear from the walls.
Need more information? Newspaper archives are one of the best online research tools. If you're searching for information on people, try Intelius.