A picture of the full coin front and back would be very appreciated, and would help us know what is going on with the coin.
Can you give a full, complete image of the coin? Currently it looks like PMD, but it could also be struck-through grease, can't tell since there's no full picture of the coin.
I would have to agree with the Dryer coin theory myself. Not a mint error, that I can see, so NAV, or No Added Value, in other words, worth 1¢
For the record, acid removes metal and reduces its weight (mass). Dryer coin repositions metal and will not reduce the weight (mass).