Just found this yesterday in a paper roll.....I can't use my microscope because it's been put in a moving box cause our house is up for sale... had 3 offers...That fell apart at the last minute....Got a POD box sitting in the front yard...Half of it is full...Just to let you know why I haven't been around lately... So couldn't use my microscope so I used my cell phone...I see someone else found a copper exposed nickel too!! Cool !! What do you guys think? I'm guessing there's a few of them out there like this
Yup, there isn't any copper "inside" to get "exposed" in a nickel, it's 75% copper/25% nickel all the way through when it's struck. Nickel is a more reactive metal than copper (sort of, it's complicated), so corrosion tends to leach away the nickel, leaving the copper behind. Those corroded spots look like copper, because they are, mostly. But it's not any sort of mint error -- just damage.
