I am fairly new to coin collecting. While searching through penny rolls I found this 1974
LMC that weighs 2.67 grams, is not magnetic, has a density of 8.61, and has a substance covering a lot of the surface on both sides. I read somewhere that people used to dip pennies in acid to try and trick vending machines. Would that explain the wonky stats and appearance of this coin? Or is there another explanation? I called and asked a local coin dealer who told me I must have read the date wrong because pennies from 1974 weigh 3.11 grams (which I already knew and was my reason for reaching out to him) then hung up on me. I didn't call him back or go to his shop since he was so snarky. I am now asking the fine people of this CCF to help me figure out what happened to this
LMC. I appreciate any information you have to share &

