Wrong die or mule

This striking error is generated by an incorrect installation of the dies on the money press. In particular, it is generated when the worker installs a pair of mismatched dies and activates the monetary press, producing the so-called "mule" coins.

In numismatics, a mule is a coin minted with designs on the obverse and reverse that are not normally seen on the same piece. The name derives from the mule, the hybrid offspring of a horse and a donkey, due to the fact that such a coin has two sides destined for different coins, just as a mule has parents of two different species. These errors can be intentional or caused by the negligence of the money press employee.

Many varieties of this error are known internationally and just think of how many combinations of different die pairs can be installed (deliberately or negligently) by choosing from all the dies available within a mint. The final product will always be a coin that does not respect the characteristics of the issue decree. In some cases, the coin may have the reliefs of the obverse or the reverse on both sides (pseudo-mule), in other cases it may have one side with the reliefs of a nation and on the other the reliefs of another foreign nation. (international mule) or when the imprints of one or both sides are changed in a year for a given coin (transition mule).


Unione Europea - Finlandia - 50 Eurocent. 2000
D/ e R/ Doppio dritto in rilievo su entrambi i lati. Collezione Pierro


West Africa - 10 francs 1959
Double obverse. Michelamk collection


100 Lire 1993 R Turrita - Repubblica Italiana
O/ Big head (II die). R/ Restricted design elements (I die). Imprint of the first reverse die. Transition mule.

Lately, I found on the market a specimen of 20 Lire Quercia I type which at first glance resembles an unstruck planchet with a knurled edge. A study has led to the result of a minting using both smooth dies and it can be deduced from the fact that the weight, the diameter, the alloy, the knurling of the rim and the perfectly raised edge coincide with the characteristics of the 20 Lire issue decree. Oak I type. Probably, it is a test carried out in the Mint by the employees to prove the knurling of the contour and therefore the function of the collar.


20 Lire Ramo di quercia - Repubblica Italiana
O/ and R/ strike with smooth dies. Perfectly formed edge. Diameter 21.3 mm, Weight 3.67 gr. Probable technical test of the collar with the aid of a pair of smooth dies, without design elements. First known specimen. Sena Coins collection

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