Mule (coin)

In numismatics, a mule is a coin or medal minted with obverse and reverse designs not normally seen on the same piece.

Opinion is divided between those who think that they are accidental, the result of an incorrect combination of a new die with one that had officially been withdrawn from use, or the work of coiners working with dies stolen from an official mint, perhaps at a time when one of them should have been destroyed.

In June 2009 a rare dateless British 20 pence mule was reported to be in circulation, resulting from the accidental combination of old and new dies in production following a 2008 redesign of UK coinage, with an estimated 50,000 to 200,000 mules released before the error was noticed.

It features the obverse of a Washington state quarter and the reverse of a Sacagawea dollar.

The details on handsome mules are often noticeably sharper, and thus are distinguishable from ordinary business strikes in circulation.