Nickels are not "silver plated". They are a solid alloy of 75% copper and 25% nickel. Your coin could have an added layer of copper that is given the name "copper wash" or "sintered plating". It is a common, but poorly understood phenomenon that dates back at least to the 1950's. The extra copper may be deposted in the chemical rinse bath or in the annealing drum. None of the existing theories explain the full range of variation seen in such errors, but the Mint hasn't been helpful in clearing up the nature of these types of errors.
Thanks for all your help! Thank you for the information. I am new to all this. I'm glad I found a place with guys that know how to help. I'll try to post a picture as soon as I can. Wondering
