Dug coin that someone tried to clean with Vinegar. Hopefully they learned that acids and copper are a bad combination.
I swing a metal detector and have a knack for finding dirty old coins.
Dirt coin restoration projects -
https://www.prodetecting.com/restorationsDirt coin restoration blog -
https://www.prodetecting.com/blog/ccawDirt coin dig videos -
https://www.youtube.com/@prodetecting