I need some help on this one. I know that the pennies are made mostly out of zinc with a thin layer of copper over it. This 1991 D looks like the copper didnt cover almost all of the memorial. All the way around the memorial you can see a thinly line of blueish zinc. With the exception of just under the steps, and on the left side at the top of the memorial. Also there is some of the bluing on the insides of the pillars. Just wondering what would cause this. I just thought it was unusual.
