Minting early US coins was more straightforward than it became in later years. All coins were either gold, silver, or copper of a specific purity—90% in the case of gold and silver and 100% in the early copper coins.
But times change, and so does the composition of coins. That has led to mistakes, especially with pennies, and those mistakes can be valuable. We’ll look at how coins can be struck on blanks (called planchets) of the right size but wrong metal.
Shifty Pennies
Most gold and silver coins remained consistent throughout their lives—90% of the precious metal alloyed with 10% copper for durability—until 1965 when silver was dropped entirely in favor of the current copper-nickel clad coins.
But pennies (properly called cents to distinguish them from the British coin of the same name) have changed composition eight times since the first 100% copper cents were minted in 1793. From 1856 to 1864, US cents were 88% copper and 12% nickel. From 1864 until the outbreak of World War II, cents were made of bronze, an alloy of 95% copper and 5% tin and zinc. When war came, copper was initially considered an essential strategic metal that needed to be conserved leading to 1943 cents being made of zinc-coated steel…the famous steel pennies.
With plenty of reclaimed spent brass shell casings available, the cent changed back to a familiar look with 95% copper/5% zinc but no tin, which would have made the alloy bronze. This brass alloy was used from 1944 through 1946.
From 1947 to 1962, cents returned to their copper-zinc-tin bronze alloy, shifting to brass again in mid-1962, where they stayed until the current copper-plated zinc coins debuted.
Profitable Pennies
The most notable “wrong metal” cents were made in the WWII era when the coin’s composition changed frequently. Sometimes a few blanks from an earlier composition remained undetected in the bins feeding the coining presses. This resulted in a some 1943 coins mis-struck in bronze and some off-metal steel planchets struck in 1944.
1943 cents were mistakenly struck on bronze planchets in all three mints—Philadelphia, San Francisco, and Denver—and all are extremely rare and valuable. Only five S-mint have been found; six from Philadelphia are known. But the rarest is the Denver 1943 bronze. Only one is known and is estimated to be worth $1.5 million today. All command six-figure prices.
1944 steel cents are extremely rare and valuable, too. There are two possibilities for the error: 1943 steel planchets may have been mixed with the 1944 coppers, or some steel blanks for coins being made for Belgium may have gotten into the bins. Either way, only eight 1944 steel cents are known to survive and are quite valuable, ranging from $34,000 at MS-55 to $158,625 for an MS 64 specimen sold at auction in 2013.
And with recycled brass shell casings used in 1944-46, streaking in some of the coins occurred. While not technically an off-metal, some collectors find those coins interesting.
A Recent Discovery
In 2017 a Minnesota collector found another unique cent. The mint transitioned from bronze to brass-plated zinc in mid-year and modified the coin’s bust, lettering, and date slightly resulting in seven varieties for that year. Philadelphia minted coins in both sizes and compositions, but no small date Denver coins were ever issued or known to exist—until the Minnesota man looked through his collection of bronze cents.
The only known coin of its type, it has been authenticated by the Numismatic Guaranty Corporation (NGC). While no value has been assigned to it, we’re pretty sure it won’t be covered by homeowner’s insurance.
A Hefty Half Dollar
When most coins had all their silver removed in 1965, the Kennedy half dollar was only reduced to 40% silver. But by 1970 even that little silver was too much so 1971 JFKs joined the other “silver” coins with a copper-nickel clad composition. But somehow at least one 40% silver planchet made its way into the hopper in Denver and was struck with the 1971 date. It remained undiscovered until 2015, reminding us that there are still exciting discoveries to be made, so always check your change.
Coin mistakes take many different forms, and some are more valuable than others. Older coins were more error-prone, and more made it into circulation than modern coins, which are made with more sophisticated machinery and inspection techniques.
Even though modern errors are much rarer, older mistake coins are generally more highly sought by collectors, both for historical value and the fact that fewer survive. But some modern mistakes bring high prices, too, so it pays to always be on the lookout.
