Looks like split plating around the mm which led to zinc rot underneath. Split plating around the mm was common in 80s zincolns. It's not a RPM
I agree.. Plating issue around mint mark There are dozens of threads on CoinTalk with the same question. Most are plating issues.
Wow, is my imagination that much more active? (aka hallucinating lol) but am I the only one that sees the giant shadow of a D right there in roughly the same style and orientation of the mint mark? This isn't the first time I've seen this, when I first saw it I just immediately thought it was drift of some zinc rot but that was on first strike. Like a "burn" on strike and much like smoke it drifts and spreads wide on the surface of the coin over a long period of time.