It's not possible to say without seeing the coin in person.
It could simply be damage that occurred after the coin was minted (it's nearly 30 years old) in which case it has no extra value.
Another possibility is a lamination error, where some of the metal in the coin has separated due to impurities or a strike irregularity, which is worth a small premium.
Or there could be some other condition.
The penny is made out of copper.
Copper
Copper pennies (95% copper, 5% zinc) weigh 3.11 grams. Modern zinc pennies (97.5% zinc, 2.5% copper) weigh 2.5 grams.
A penny.
PENNY
A 1993 penny is composed of 97.5% zinc and 2.5% copper. Therefore, the percentage of copper in a 1993 penny is 2.5%.
A penny
A 1983 penny is made of 95% copper and 5% zinc. The actual weight of copper in a 1983 penny is approximately 2.5 grams.
did they make 1982 copper penny by mistake
zinc is 97.5% of the penny and copper is 2.5% of the penny
Yes. Dissolution of a copper penny would indeed be a chemical reaction.
Those are 95 percent copper. A US penny weighs 3.11 grams. Of that, 2.9545 grams is copper.