Contaminated Iron is a miscellaneous item that can be found in mining carts on levels 1-3 of the Nashkel Mines. In the original and enhanced versions of Baldur's Gate this item has no use other than providing some backstory. It is associated with the quest The Tainted Ore which was originally cut from the game and can be restored only by using the Unfinished Business mod.
|“||This iron looks to be coated in some sort of toxic substance. Though just speculation, you wonder if this could be what's been contaminating the iron of the region.||”|