Therefore I prefer to say "mule" for coins struck at the mint from mismatched official dies.
The distinction official/unofficial is crucial. Official mules are for the most part vey rare, and interesting as error coins and for showing a chronological connection between dies that we otherwise wouldn't have known were in use at the same time.
Would you also agree that the term 'mule' is inappropriately used when it makes the assumption that the mismatch was an accident without evidence that the
mint did not make the pairing intentionally? The most common examples of this, to me, are the pairings of
Constantinopolis and
Urbs Roma obverses with Two Soldiers reverses. Another group is the Eastern
mint denarii of
Julia Domna using masculine reverses. While these are not exactly common coins they are much too frequent to be accidents beyond a level of just not caring what
reverse die was used. Several of the
Alexandria mint Septimius reverses were copied from other rulers' coins including the date numbers appropriate for
Lucius Verus or
Pertinax but not Septimius but I have seen no evidence that the dies used were ever used for the appropriate rulers. Are these 'mules'? I believe not. To be a
mule, should a die pairing be known used separately with appropriate opposites adding evidence that the coin is official rather than just a
good metal but unofficial products? Obviously many solid unofficial coins are betrayed by their unofficial
style but I am not always comfortable saying where the worst official and best
counterfeit dies meet in terms of
style. I'll accept being
fourree as evidence of being unofficial but being solid is not as certainly an indicator of being official. One place I am uncomfortable in this regard are coins of
Magnentius which raises the question on whether the
rare Falling Horseman coins of
Magnentius are intentional official,
mules or barbarous. What coins, then, are left to be called
mules?