Hi Tim,
Not an error, case of poor storage and environmental damage I reckon. Copper coins should be lustrous or brown-dark brown/black. Blue or Green is most likely verdigris.
Not an error, case of poor storage and environmental damage I reckon. Copper coins should be lustrous or brown-dark brown/black. Blue or Green is most likely verdigris.











this is a 1916 half penny not sure if this is a error or not, see the blue on it






