This is quite common in copper plated zinc core cents. Once the thin copper layer is pierced, the zinc core underneath corrodes rapidly, particularly if exposed to the elements. As the zinc corrodes it causes the copper plating to bubble up. The corrosion is even fast if the coins spents any time near the ocean. Your coin looks like it was minted with a slightly higher strike pressure which is known to effectly tear the copper platting, particularly on the rim side of the mint mark and other lettering. This too is quite common. In short, its a damaged coin, but keep searching
Thanks for the reply lawdogct! That certainly would explain those marks -- I never knew this could happen, nor that it was common. So, it's sort of like getting your skin cut and having bacteria enter the cut and produce gas that would swell the skin up (eg, gangrene). Some of the "bubbles" don't appear to have surface breaks, but I suppose they may be small enough to not be visible (at least using the equipment I have on hand).
Just think all that damage occurred in only 15 years. Just think how bad they will look in 50. Back during WWII the Germans minted many coins in unplated zinc. Today, they have little value because of their propensity to turn to a pile of zinc oxide.
I know. I used to go coin shooting with a metal detector, and zinc coins buried in the ground do not age very well. On the other hand, I wonder if eventually this will cause zinc cents to increase in value since their population will naturally decline over time, just to deterioration.
Your welcome. Another common occurance with plated cents are the bubbles you mentioned. Its a failure in the plating process, I don't recall the specifics. But if you take a look at a handful of plated cents, particularly those from 1986-1989, you will find many with bubbles.
