I was going through my coin books and noticed this 1969 cent seems to be losing it's copper coloring. I find it had to believe I would have put it in a cardboard wrap then into the coin book when it was looking the way it is now...But, I might have. I tried taking a picture with my microscope but it just was not coming out like it should have so I took a picture with my phone....What do you guys think caused this?