1993 d penny that looks brass. I really like the way this coin looks but I'm confused as to whether this is a mint error or just electrolysis or some other post mint modification
Zinc blanks falling into the plating bath was a known processing problem when the mint first started purchasing copper plated zinc planchets in 1982 and 1983, so it's possible that there are coins with a higher percentage of zinc in the plating. The problem is that it is nearly impossible to do a non destructive test to show this. MOst NDT analysis penetrate the surface slightly and pick up the the zinc in the blank. Some of the scientists on CT may know of some advanced analytical methods but they would probably be very expensive I have a couple 82 and 83 cents that I found 30+ years ago that I feel are brass plated. However, there is no way to prove it, so they are worth face value. My opinion isn't going to convince anyone. BTW, you can't rely on color. Copper can react with too many things.
