I found two 1953 pennies that have a silvery appearance. I mean they look like the average penny but they are silvery instead of the normal red copper. What type of error would this be?
In the good old days, when any curious child could get hold of hideously toxic and corrosive chemicals, it was fun to take a nice shiny penny and rub it with liquid mercury. The mercury formed an alloy (amalgam) with the copper, and that amalgam was silver. The silver would stay for quite a while, but eventually it would wear away.
