It appears that the coin was dipped in acid, so the reduction in weight would not be surprising. Chris
corrosive environment damaged coin, after the mint. from my experience with finding them coin hunting, they won't go through a coin counting/sorting machine and will get rejected so spend it in person or take the loss. with the surface condition being the way it is I'd expect the copper on the edge to be eaten away even more and look like a railroad track, between the surface and the edge copper this is where it's losing almost a gram.
