Originally Posted by Lu1gi
im pretty sure it is only brass, and it is not the terquoise type of thing you see on copper, its like grass stains on the paper towel, if you will . . . pretty gross.
Sometimes with metal lathes and presses they use like a chemical agent to help the process, like sort of a lubricant. Im not an expert on metal working, never really done much of it. But it could just be left-overs of the process