Been going through old hand rolled rolls and came across this rather odd 1920-P. At first I assumed it was just acid corrosion or some kind of PMD, but regardless I weigh any planchette that seems odd or has a unique tone in case it may be a planchet error or foreign planchet. Today I started going through the circulated teens, 20's, and 30's that were in rolls and found various other with similar appearances/clear PMD/acid corrosion and weighed each. The general average of the regular circulated was around 3.0g-2.95g accounting for any wear. The others of similar damage ranged around 2.95g, and the lightest prior to finding this one was 2.905g. This one when weighed came out to exactly 2.375g, yet for the amount of whatever wear/damage to it, the lettering is still relatively clear and definetly stands out from all the others that I've tested/compared it to. Anybody have a clue what could be the reason for all of this? 0.625g underweight just seemed to be a significant difference even considering the amount of corrosion. Especially since I tested other clearly damaged or worn examples and even those were never lighter than 2.90g.
I have several coins that look like that. I believe its from being under water for a long period of time. I found mine near the water treatment center in my town. I also have a few nickels from teens through the fifties that have shrunk..
Looks like a couple hundred pre 1930 cents I bought from a private collection a long time ago, after they were pulled from a drain in a church fountain years after the fountain was removed. It was a local wishing well from old timers that tossed cents into it when they were in their younger days.
For the same reason that acid brings out dates on Buffalo nickels, it eats away at cents while leaving the devices visible. The other 5/8 gram of your cent dissolved away into the environment.
I think Jeff is correct with the acid ( whether intentional or environmental ). Measure the diameter. With that much difference in wt. acid should have reduced the diameter proportionally to a normal cent. The nominal is 0.75 inches.
Looks almost the right size, just thinner and worn. 7/10 of a gram. That's a lot of copper (ions?)/ atoms.
The thickness seems to be reduced by about 1/6 measuring on the large monitor, that would be estimate of about .5 grams from thickness, so the remaining .2 grams +/- could be from change in diameter, not seen in the photo. Even with just rough estimation I can see it as acid.
The change in diameter is ahown in the photo. Look to the right of the picture. You can clearly see the diameter is smaller on the damaged coin on top.
It appears that the edges of both coins on his finger on the right side are close to aligned ( since flesh is soft), but on the left side the coins disappear into darkness and seemingly behind that finger, so how could one determine the amount if any? You say "clearly see ....", but I don't feel that is so. I am sure it is less, because that is what acid does, but I wanted to be sure of that fact by seeing it. I can see the thickness of the top coin is thinner, but I can not see that the diameter is less.
These are a few of the measurements I got: My 1920-P Cent- Mass: 36.66 gn Diameter: 18.65 mm Thickness: 1.20 mm Volume: 340.23 mm^3 Density: 0.108 gn/mm^3 Vs. Normal Cent: Mass: 48 gn Diameter: 19mm Thickness: 1.43mm Volume: 405.45mm^3 Density: 0.118 gn/mm^3 Not sure if this would determine anything— I'm sort of guessing as far as what comparisons would give the most relevant info, so Im not sure what kind of deviation would be considered abnormal or not. Its also been a while since my last math/science class, so I could be totally on the wrong track here lol
I'd expect the acid to eat it away at a constant linear rate, more or less, although different work hardening around the edge would probably change the rate there. But if the thickness went from 1.43mm to 1.20mm, decreasing by .13mm, I'd guess the diameter would decrease by approximately the same linear amount, not by the same proportion. That means the diameter would go from 19mm to 18.87mm. So the diameter of the (hypothetically) acid-etched cent isn't larger than I'd expect. I have no problem believing that the edge would get etched preferentially, meaning the diameter would drop more quickly than the thickness.
