That picture is so blurry you can't see anything. Most definitely it is the Clad Cupro-Nickel over the copper core. Not silver. Not cooper.
Actually it feels like rough metal . I’ve tried to scrap it it off with my thumb and wouldn’t come off.
May I ask what crud means? So if you can feel a difference in the texture of the coin from smooth to rough it’s considered crud?
Something stuck to the coin AFTER it left the mint. It really doesn't matter what it is or what caused it, it's a damaged coin.
I beg to differ. What sticks to a coin and leaves a affect like this ! It is cemented in the coin and would send to anyone out there.
There is no way anyone can say for sure what it is from an image. We do know that it is not a mint error. That leaves corrosion or something stuck to the coin. Most people in this hobby would call it a damaged coin.
There are very strong adhesives that do that. If you feel that we are wrong then send it to a TPG, third party grader to have it attributed as an error. You can choose from companies such as NGC, PCGS or ANACS. Google them to get more info. It will cost to do so of course. Then come back with the results and proove us wrong. Our answers to you are free. Many of us have been collecting mint errors for a very long time so we can truly tell you what you may have. Good luck. Mr. Ed Specializing in collecting Mint Errors since 1985