1987 D Doubling / Rim Error?

It's called a split plating issue, and the greyish colour actually the zinc core showing.

to the CCF!

to the CCF!

This is sometimes called Split Plate Doubling, but it's not collectable. The copper plating over the zinc core was stretched to the breaking point and separated. The zinc core may start to break down with further exposure to the elements. Some coins like this corrode to the point of sections of the coin breaking off or leaving the remaining copper hallow.

You may want to keep it as a nice study example, but if not, spend it before it disappears!