It is 99% pure tin over the copper. I was worried about not getting a very good price if they suspected it wasn't copper. I'm not worried about recovering the tin - as I am not sure how. Each piece of copper can be between 20 & 50 pounds, then it is coated with the tin, so I see good weight in copper, but I wasn't really sure about the tin part - leave it on or buff it out. If there is a way to recover it, that would be awesome, but I'm not sure how to do that.