I have this dime that's pretty nuts. I don't know what to make of it. It's a little beat up but the trippy thing is that the ridge is none like I've ever seen. The grooves are sunken in. Like, the ridge is there, but the copper where the grooves are sunken in. I don't have a good picture but here are a few.
Railroad rim? Looks like a partial collar error to me but.... I'm still new here but someone here I'm sure will know..gl & peace!
Can you get a better set of pics? An acid-dipped coin can have the center clad section eaten away, leaving the coin with an "oreo" look to it. The reverse looks rough, thus my reply.
A railroad rim has a single flange, not a groove down the center of the edge. (Edge, not ridge.) I agree that it could be an acid-dipped coin but we would need better - clearer - photos to tell for sure.
Most likely soaked in acid. One thing to check is of the reeds are still visible on the copper core. The reds are formed when the metal is forced against the collar, so if the reeds are still there that would mean that at one time the copper was out at the same level and t coppernickel layers. Since acid attacks all the surfaces of the copper equally the reeds remain even as the copper is eaten away.
