Most likely environmental damage.. It's been explained very well what it is.. I even posted pictures.
One summer I was beachcombing and found a beautifully-sharp 1938 Buffalo Nickel (didn't know enough about coins to look for a mint mark). I don't know how long this coin was in the salt water, but it was as brown as a nut. I really don't think that it requires very much environmental stress to make a nickel begin to discolour, like the one I found did. If you buy a coin like this, thinking that it's a "rare error", I hope you don't spend a lot of money on it. montynj.
P.S.: Most of the nickels that I dig up while metal detecting happen to be brown ones.... astounding good luck, mus'be.
Environmental damage toning can occur just on one side. Nickels have no clad layers so it cannot be missing clad layer.
Ok check this one out.... I just found a 1917 buffalo that's brown like the pictures. But has very good lines and definition. May be a two feathers no mint Mark I believe. So I took your advice and I weighed it. It's ever so slightly smaller in diameter. Like half a millimeter smaller. And it weighs 4.52 grams and is exactly as thick as a pre 1982 penny. Someone explain that one haha...
Explanation: Go back in the thread to the post I submitted re: razor-sharp looking 1938 Buffalo Nickel found in salt water surf. Either that, or succumb to mass hysteria hahahee.
No.. Did you read any of the posts on this thread with the answer you seek? It is Environmental Damage.