Your dime has either been sawed in half or it is an incredibly rare error. Because of your description I believe that it is an error. I suggest that you wrap it in a very soft cloth and do NOT clean it. I have no idea how this could have happened. I suggest that you go to www.pcgs.com once you are there click on submission center. After that click on PCGS authorized dealers. When that screen comes up click on Mint Errors located under the Browse by Specialty section. When the screen comes up, scroll down until find the coin dealer located closest to you. Once you find a dealer located close to you bring it to them ASAP and follow their directions on what to do next. If what you have is genuine than you definitely have one of the ten all time rarest errors (based on your description).
