POSSILE ERROR COIN?? [opgelost]

I have a 1976 no mint jefferson nickel that appears to be copper???? How can I tell 

Hello,

Except during  wartime, the Philadelphia Mint did not use the “P” mintmark on nickels until 1980.

It's not an error - your coin is suffering from environmental damage - it's been exposed to the outdoor elements at some point during its journey through the  world.

The copper nickel alloy turns that color when it is exposed to the elements.

Look at this:

https://www.coincommunity.com/forum/topic.asp?topic_id=330383

Ok. That makes sense. Thank you so much. 

You are welcome my friend.