There is no telling what may have been used to discolor this penny. Back in the 50's & 60's, kids used pencil erasers to brighten pennies, they were dipped in mercury and even Brasso was used to remove the patina. It's even possible that your coin was charred by heat and then scrubbed sometime afterward. One thing is sure. It's not a Mint error. What you need to do is learn more about the minting process and how coins are created. Only then, will you be able to rule out such dreck. Chris
