Fun facts on pennies
In 1943, at the peak of World War II, pennies of zinc-coated steel were made for a short time because of war demands for copper. A few copper pennies from 1943 were produced from the 1942 planchets remaining in the bins. Similarly, some 1944 steel pennies have been confirmed. From 1944 through 1946, salvaged ammunition shells made their way into the minting process, and it was not uncommon to see coins featuring streaks of brass or having a considerably darker finish than other issues.
1974 aluminum penny from the Smithsonian
During the early 1970s, the price of copper rose to a point where the penny contained almost one cent's worth of copper. This led the Mint to test alternative metals, including aluminum and bronze-clad steel. Aluminum was chosen, and over 1.5 million of these pennies were struck and ready for public release before ultimately being rejected. The proposed aluminum pennies were rejected because of two factors: vending machine owners complained the coins would cause mechanical problems and pediatricians/pediatric radiologists pointed out the radiodensity of the metal inside the respiratory and gastrointestinal tracts was close to that of soft tissue and therefore would be difficult to detect in X-ray imaging.[6] One aluminum penny was donated to the Smithsonian Institution.
The penny's composition was changed in 1982 because the value of the copper in the coin started to rise above one cent.[7] This was mainly caused by inflation. Some 1982 pennies use the 97.5% zinc composition, while others used the 95% copper composition.
One can hear the difference between the bronze and copper pennies and the newer, zinc pennies by dropping a coin on a solid surface. The predominantly copper pennies produce a ringing sound in the 12 kHz range. The zinc coins make a noise that is different.[8] In addition, a full 50-penny roll of pre-1982/3 pennies will weigh 5.4 oz. compared to a post 1982/83 roll which will weigh 4.4 oz.
