Given to me for my collection. I'm not 100% that it's actually copper, but I can see some shiny lines that looks like copper. It's not very old, it's blackened like a penny, and it still has some detail. I've never seen one of these quarters turned into this color..except for the one I have.
Usually, quarters that spend a little time in water end up like this. I used to drop a few clad coins into my aquarium now and then, and they would look like that when removed.