Green corrosion is only "acceptable" on coins under certain very specific conditions. The coin must be either:
- very rare
- more than several hundred years old
- have some kind of historical provenance (eg. shipwreck coins, or coins found on the site of goldfields, POW camps, or other historically significant sites)
- made of an unstable alloy that self-destructs and will turn green and corrode, no matter how well you try to preserve them (yes, Tannu Tuva and other Soviet satellite states, I'm looking at you guys when I say that).
In short, "green meanies" might still be collectable if non-green examples of those coins are difficult or impossible to obtain. Your coins are all modern, and common; some are definitely metal detector / ground finds, others have more of a "flood damage" look to them. It is still super-easy to obtain non-green examples of all of these coins. So the only people interested in buying such coins are scrap metal merchants.
Or let me put it this way: when I take bulk lots of coins (Australian or foreign) to a coin dealer for sale, I make sure that I pull out all the corroded coins like these before I try to sell them - because the coin dealer will definitely give me a lower price if I keep those corroded coins in there. So from that point of view, coins like this actually have negative value to collectors and dealers - you have to pay people to take them off your hands.
Yes, this does mean I currently have a large (and growing) pile of corroded coins that I'm not really sure what to do with.
One final word of warning. On some of your coins, the corrosion is powdery and pale greenish-blue. This is a very contagious form of corrosion known as "bronze disease". It is called that because it can grow and spread, just like an actual biological disease (even though the cause is chemistry, not biology); it can cover the entire face of a coin, and can even jump from coin to coin if pieces of the corrosion dust break off and land on another coin. So if you plan on keeping these coins, don't simply toss them all in a big bucket along with non-green coins and leave them somewhere warm and moist. You'll end up ruining more of your coins that way.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
Posted 02/20/2023 12:09 pm
