1979 Copper Jefferson ? And A 1983 Jefferson With Issues

I suspect the copper nickle was heated .

If you heat nickle very high in vinager 550 + it starts to turn copper.
It even has marks on it that look like it was layed on a hot surface say a baking pan.

I know I put some nickles in vinager heated to 550 and for got about um , well 20 minutes later
my whole house stunk !

took out the pan slide the nickles in water this is what I got red powerdery nickles
scrubbed a few off

copper nickles ! some all copper some blotchey some half mainly the side that was facing on the metal pan
I suspect that pan got hot and the metal on metal made the copper start to bleed from the other metals

The 83-P has Machine Doubling on the mint mark and Die Deterioration on the outer devices.

This one was the same way,,but didnt look as cool as yours