Hey everyone, I have only come across these three that have this particular blue green that I at first thought was zinc rot. But the color is also showing on edge of each coin. Is discoloring from alloy mix or is there some other reason this can occur. The 2004 has this pattern on both obverse and reverse and wondering if this is a polishing cloth strike through or is it PMD? Thanks again for any information.
yep what paddyman98 said, it's not zinc rot, but it will be once that gets through the copper plating. I'd call it "car cup holder toning".corrosion for them sitting in a wet environment like a car cup holder.
