Coin mistakes take many different forms, and some are more valuable than others. Some of the more interesting, rarest, and most valuable, are hybrid coins known as “mule coins.”
Like the stubborn quadrupeds, mule coins are the result of cross-breeding. One side of the coin is one thing, and the other is another. This typically happens when dies get mixed up on a machine at a mint and the hybrid coins go undetected.
Mule coins have been around nearly as long as coins have been made. Mules have been found among ancient Greek and Roman coins, and some experts speculate that some may have been made deliberately, rather than being true mistakes. One authenticated ancient mule coin is from the Carthage mint in the 7th century. Others have come from mints from Persia to England.
Mule coins have been made by counterfeiters, but a few were made deliberately, usually at a mint (without authorization) as novelties. This happened sometime between 1867 and 1878 when some Gobrecht silver dollars were made as restrikes by mint employees. Other times, pattern coins are made for testing new designs and may be struck as mules with the intention of scrapping them. And sometimes, necessity has dictated using mismatched dies such as when dies become scarce or broken and “emergency mules” are made. This happened notably on 1795 and 1798 gold Half Eagle coins. This was a very rare occurrence, mostly in the earliest days of the Mint when die failures were more common.
Magicians and other tricksters have been making double-heads and double-tails coins for a long time. These coins are made by hollowing out one side of a real coin and shaving down another to fit. Most are well made and convincing, but you can usually see a seam along the rim under magnification. Some occasionally make it into circulation, so if you find one, before you quit your job take it to an expert.
Modern Error Mules
Older coins were more error-prone than modern coins, which are made with sophisticated machinery and inspection techniques. But mistakes do slip through from time to time. Some rare known mule coins include:
- An 1859 double-headed Indian cent. Only one is known, but experts think there may be others given that it came from a production run.
- A 1918 Philippines coin minted in San Francisco with 5 centavos on front and 20 centavos on back. It’s not known how many were struck but is considered somewhat rare.
- A Washington quarter with two tails. Since it’s “tails” on each side, there’s no date on the coin, but experts figure it was struck in 1965. It’s the only authenticated US coin to have ever been struck with two reverses. Only one is known to exist.
- 1995 Lincoln cent obverse struck on a Roosevelt “silver” dime planchet with the dime reverse. Only one is known.
- 1999 copper Lincoln cent with a dime back. It’s not known how this coin got made at the Philadelphia mint, but it was found a roll of pennies by a collector. Speculation is that the mint was either testing new dies and someone failed to remove it from the scrap bin or that it escaped after the error was corrected. Only one is known to exist, but there could be more.
- Sacagawea dollars with a Washington quarter face. They were probably struck in 2000 at the Philadelphia mint as the “States” quarters (which have no dates on the front) were going into production. Seven of these coins have been found, including in vending machines and change. It’s the only US coin known to be released with a mismatched front and back. Six of the seven have been on the market for prices as high as $117,500.
The Famous 1959-D Mule Cent
The reverse design of the Lincoln cent was changed from wheat stalks to the Lincoln Memorial in 1959. But in 1986, a retired police officer claimed he had purchased a 1959-D cent with the wheat design on the reverse. He sent it to the Treasury Department for authentication and it was deemed real. Then several grading services expressed doubts and it was resubmitted. Again, Treasury said they found no evidence it was fake. Then, a noted counterfeiter claimed he made it, which was later disproved, but auction houses have been wary. Even though they have sold it, it’s been with a disclaimer that they don’t guarantee its authenticity. That’s partly based on the fact the coin is the only known example, and if authentic, more would be expected to surface. Nonetheless, it resold recently for over $31,000.
Occasionally a mint may use a proof die to make coins for circulation. The coin is usually proof quality on one side only, but the higher quality strike is noticeably sharper. Not true mule coins, they are rare, nonetheless, and may bring slightly higher prices if authenticated.
Collecting Mule Coins
While not terribly rare, some ancient mule coins can bring several thousand dollars. Modern mule coins are less likely to be struck, and modern US mule coins can bring very high prices. Modern mule coins are also known from other countries, and several from places like Australia and Canada are easily found at reasonable prices.
There are thousands of error coins of various types still in circulation, so if collecting them appeals to you, learn as much as you can about the subject. Books and articles are available online, and there’s an organization called CONECA devoted to the education of error and variety coin collectors. Visit their website, conecaonline.org, for more information.