It looks like it may have been varnished, and only a little still remains on the coin. What does the reverse look like?
Another name for it is lacquering, it was common to do it to cents and other coinage at one time by the people who liked their coins smooth and shiny. I don't know if this is actually what happened to the OP cent, just guessing
My first thought was a lamination error but then I saw the coin at the top. That convinces me that this coin is damaged. Probably by glue or lacquer which is wearing off from handling.
Maybe try soaking it to see if you can remove the gunk? Just as an experiment so the next time you run across a coin that is similar, you'll know.
hi @TriciaS you have a good eye for catching this PMD as does @paddyman98 for seeing the build up under the bust. there's no added value for you this time, sorry. good luck to ya
Thanks think if i can get a lot of the pmd by sight then when i find a good one i will spot it better maybe
@Trisia ...if you study the basics first, like how dies are made and the minting process, then when you see PMD you won’t waste any time on them. The minting process is finite and well documented, as is the way dies are made. There are a trillion ways to produce PMD...jmho...Spark