It appears to be some type of environmental damage. As Dearborn mentioned, it's possibly been in the ground a while, or maybe just sitting at the bottom of a cupholder exposed to spillage from acidic soft drinks. Plus, this dime has some pretty significant rim damage, as well. As you mention, it's still worth 10 cents, though!
Member of SPMC, FCCB, ANA and ANS.
My U.S. Classic Commemorative Complete Set: https://www.NGCcoin.com/registry/co...sets/278741/
My U.S. Classic Commemorative Complete Set: https://www.NGCcoin.com/registry/co...sets/278741/
























