Copper Pennies - Pre-1982

Since I've been metal detecting I've found out something about pennies I didn't know. I knew they changed the metal composition a few years ago because the price of copper got so high the value of the penny was worth more than 1 cent. I didn't realize that this was changed in 1982! I thought it was just, maybe 5-10 years ago. And, I didn't realize how much this new penny composition corrodes when in the ground! Finding these new pennies that have been lost for several years, the penny is sometimes 30% GONE! The older copper pennies are always completely intact.

In 1982 they minted both copper and copper coated zinc.

Drop Test for Copper and Zinc Pennies
If you don't have a tenth-gram scale handy, you can use the "drop" test. You need a hard Formica surface, a known copper penny, and a known zinc penny. Drop each one onto the table, listening to its distinctive sound. Zinc pennies have sort of a flat "clunk," whereas copper pennies have a higher-pitched, more melodious "ring" sound. Once you have a good feeling for how each type sounds, start dropping your 1982's one at a time, listening for the sound they make, and you should be able to sort them out by metal composition. Obviously, this test isn't as reliable as weighing them, but it should help you sort most of copper and zinc pennies.

As you can see by the picture, the copper pennies hold up much better.