What is the most likely cause of a Lincoln Cent (1930) to turn blue?
I know that exposure to sulfate will cause the copper to react and make a blue tone, but I also have read that cleaning a copper coin with cyanide will cause the copper to turn blue.
The 1930 cent is a coin that would fit the profile of a cent that may have been dipped in cyanide, so I'm not certain if this coin has been cleaned or perhaps it is really a blue uncirculated coin. Does anyone have any knowledge of the frequency or likelihood of finding genuine blue toned Lincoln cents?
7 years ago