What are the materials of old pennies?

Old pennies, minted before 1982, were primarily made of copper. Specifically, they were composed of 95% copper and 5% tin and zinc. This particular alloy, known as bronze, gave pennies their distinctive reddish-brown color and enhanced their durability. Copper pennies were introduced in the United States in 1857 and remained in circulation until 1982. They were often referred to as "copper pennies" or "pennies" during that time.

Starting in 1982, the composition of pennies changed dramatically due to rising copper prices. The new pennies are composed primarily of zinc, with a thin layer of copper plating. This change allowed the US Mint to continue producing pennies at a lower cost while maintaining their familiar appearance. These copper-plated zinc pennies have been in circulation since 1982 and are still used today. They are commonly called "zinc pennies" or "copper-plated pennies" to distinguish them from the older copper pennies.