1965 Roosevelt Dime Weird Egde

Hello, this is my first posting and I am not an avid coin collector (just happen to work at a grocery store as a checker so try to collect silver)
This is what I found. I noticed in a roll of dimes a dime that had a black stripe sandwiched as the copper would be all of the way around on the edge. It is dated 1965. The stripe and top and bottom layers of the coin are all perfectly (to my untrained eye) even the whole way around the coin. I noticed that the black stuff could be coaxed out with some considerable scraping (I used the pin on my nametag) and seemed almost a shiny powdery black. Underneath that in a few very small spots you can see copper, but if all of the black stuff was removed the coin would have the appearance of a train wheel, that is the middle of the egde is inverted. My first thought is it is just filled with dirt after years of wear, but why would there be a ridge at the edge to which dirt could get stuck in to begin with? Also, someone suggested it could be a "trick" coin that you can pull apart but if that is the case, how to get it a apart has eluded me. can anyone help?