Dark charcoal color dime looks like maybe a annealed error not sure I ran hot water over it nothing came off so maybe it was in the cooker to long at the mint
It has a bit of copper tone peaking through on reverse I still myself I'm leaning that it's a annealed error,otherwise this toning on it would have washed of it looks more permanent to me
I metal detectors, the majority of coins I pull out of the ground look just like that but you be right, good luck
Improper annealing doesn't cause copper to show through the outer clad layer. Also, toning is caused by a chemical reaction with the metal surface. Hot water is no more likely to remove toning than it is to remove rust from your car. If it was an annealing error, the copper seam along the edge of the coin would be bright. If the copper core is discolored, it's environmental damage. Hope this helps
