1977 Aluminum Penny!

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The 1974 aluminum cent was a one-cent coin proposed by the United States Mint in 1973. It was composed of an alloy of aluminum and trace metals, and it was intended to replace the predominantly copper-zinc cent due to the rising costs of coin production in the traditional bronze alloy. Of the 1,571,167 coins struck in anticipation of release, none were released into circulation. To encourage congressional support for the new alloy, the Mint distributed several examples to US Congressmen. When the proposed aluminum cent was rejected, the Mint recalled and destroyed those coins. However, despite the recall, a few aluminum cents were not returned to the Mint, and those coins may remain at large. One example was donated to the Smithsonian Institution, while another was alleged to have been found by Albert P. Toven, a US Capitol Police Officer. A 1974-D specimen was found in January 2014 by Randall Lawrence, who said it was a retirement gift to his father, Harry Edmond Lawrence, who was Deputy Superintendent at the Denver Mint. Randall planned on selling it in a public auction, but the Mint demanded its return, saying that the coin was never authorized for release and therefore remains U.S. Government property. Lawrence (and his business partner at their coin store, Michael McConnell) ultimately surrendered the coin when the Mint showed that the aluminum cent had never been authorized to be struck in Denver, and there was no evidence that the coin had been a gift of any kind.

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At least 1 example of an aluminum Lincoln Wheat cent struck in 1942 to test a possible alternative composition to bronze for the following year. Unlike the 1974-75 aluminum cents, this coin appears to be legal to possess and was sold at Heritage Auctions in May 2009.