Conservation Needed Here Or False ID On PVC? (1931 5 Reichsmark)

Hi all — I am new here and this is my first post!

A part of the reason I joined is that I've been having a tough time lately with not being sure whether what I'm looking at on a coin is PVC. I've rarely come across the super obvious "green mask," mostly just between one and a couple green flakes or flecks, and there's not a lot I've been able to find out about how to treat cases like that.

One example is this 1931 Germany 5 Marks KM# 56. It's a fave of mine, but recently noticed a few little greenish blots around the lettering. It doesn't seem to be present elsewhere. The coin is .50 silver fineness and has a kind of mossy patina which I've seen on many if not most examples.

I've used acetone a few times on other coins, but my hang-up here is that a) I don't want to disturb the patina or cause some weird reaction because of relatively low silver fineness, and b) I am not 100% sure that it's PVC residue.

I would be really appreciative of any insights as to the likelihood of this being PVC, cases generally where there's like one little green flake and not much else, and if acetone seems like a bad bet here.

Many thanks and glad to be here!
Nathaniel




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