She sees metals and conductive materials. She can't see anything else. I.e. when seeing Wolverine behind a wall, she only sees his metal skeleton. When looking at a machine, she could see all metal parts including those inside other parts, but she couldn't tell which wire was red and which blue cause she could not see their plastic insulation at all and she could not read letters painted on. Looking at a door, she could see the metal hinges, the lock and the brass handle but not the door itself or anything on it. Looking at a gangbanger, she could see his uzi, his spare bullet cartridges, his jewelry, his belt straps, the metal parts of his watch and any metal coins he had on him but not his face, his clothes, paper money or his body at all.
And so on. I'd say that knowing the type of material would require a technology check as normal. Recognizing cooper wires or iron bars is trivial for most people. Telling one type of steel from another or steel from titanium is a lot harder to do visually. Telling platinum from iridium is almost impossible.