The reverse shows a circle at the bottom left of the memorial. This doesn't look like any zinc rot I've seen and everything to my knowledge tells me this is in the die. I've zoomed in every way I can to exclude zinc rot! Maybe someone has seen this and maybe it's better left alone I don't know ! Opinions please!
I am going to take a wild guess..... and say that it is a plating blister that popped. %&#@&& ????? This one is going to need professional opinions from others.
Hey I like the guess and a good one! I had thought of this also before posting. This wouldn't explain the inner circle retaining it's plating ! Your thoughts on this?
Is it zinc? Maybe it is a bubble that was in the copper itself. There are many tiny ones on the obverse. This may have been a big one. "It's a zit... get it?"
Plating bubble. Not a Die Issue. They come in many forms and sizes. Can look as weird is your example.
Plating break, zinc rot starts (zinc converts to zinc oxide) causing the "blister" which opens at the top. Coin gets into some mild acid solution and dissolves the zinc oxide leaving the empty plating blister.
