Can I get material properties at a trace hit point?

Is it possible to tell what the metallic value of is of the hit point of a trace? For example I have a complex object with metal and wood parts in the texture. I’d like to allow attaching a magnet to the metal areas only. If I recall correctly there was some kind of a physics material masking in UE3 but I can’t find anything like that now.

This was a really good question… Does anyone have an idea?