It was in a 2 X 2 but I can't tell where it was stored at one time. It was a green coating over Liberty that was peeling off. I am guessing nobody wanted to do anything to it. It is a year I have several of and selling off but this one I will get stuck with so I am soaking it and keeping it.
It peeled when he soaked it in acetone. I don't think acetone affects verdigris? Well, it never did when I tried it.
It all depends on how you define corrosion. If the material of the coin is involved in this decomposition, it would be corrosion, but if this is just a layer on top of the coin metal, the metal would not necessarialy be affected, and it would not be corrosion.
Yes, I am soaking it now and should post a pic but it looked like some type of lime green enamal type of substance on top of the coin. I will pull it out and take a picture.