The scan shows a much different picture than a magnifying glass, but I believe this 1991-P Quarter shows signs of Strike Doubling. What do you guys think?
Well, I'm no expert, but I think it may be die deterioration doubling. The double is wider than the device it doubles. I.e., the doubling on the L is seen on both the left and right of the L. But it's just a guess. If an expert happens along, please discuss the diagnostics to determine the different types more properly. (The variety of names is part of the problem -- I'm not sure if "strike doubling" is the same as "machine damage doubling.")
I would think it's a peculiar form of die deterioration doubling. But you also may have surface film doubling occurring here. That occurs when the coin or die is covered with a thin layer of oil or grime. As the planchet expands beneath the strike, the grime extends beyond the struck design elements in a radial fashion, as seen here. Then again, some Canadian coins show a similar form of doubling, which is said to be due to a breakdown of the chrome plating. But our dies don't have a chrome layer. Study under a microscope would undoubtedly clarify the situation. FYI, machine doubling is the same as strike doubling, mechanical doubling, machine doubling damage, machine damage doubling, ejection doubling, and shift doubling. Too many names, for sure.
