Strange discolouring on coin - some kind of acid? [gelöst]

Hello,
for some time now I had this coin, I found it at the beach while on vacation.

The green oxide (?) on the edge of the coin was already there when I found it, but the strange bleaching on the one side wasn't.
I kept the coin in a small box (wrapped in a bandage for some reason) first and transferred it to a cheap album later.

The album was this one: https://www.amazon.de/dp/B07FCPHLNQ?ref_=cm_sw_r_cp_ud_dp_GMED21MBH34M30PJDVN3

I know its not a rare coin or anything, I am just curious if someone knows what might have happened here.

Anyways, heres the coin:


Thanks in advance

First could you show the spot it was in on the album (might give a better explanation). Second, though I've not seen examples where PVC plastic has turned a coppery colored coin white, the greenish blue tint around the edges of the stain and the coin do suggest that PVC plastic is a definite suspect.

Maybe the seawater, once you found it on the beach?

You said it was wrapped in a bandage? I think it could probably be the adhesive on it or left over chemicals from sanitizing it in the factory. As for the green stuff on the sides it's just corrosion from the sea water probably.

Thanks, the bandage should be it. The green residue comes definitely from the water, I have many other coins from similar circumstances that have that type of corrosion too, it was just the white discoloration that was strange to me. Im sorry that I didnt answer the questions posed earlie, I just kind of forgot…