Why Are So Many Ancient Coins Struck Off-Center?

Thanks Sap and thg for your input.

Sap, do you have an estimate of how many coins a 3-man team could crank out in a day?

If my reckoning is correct, that should be about 1000 coins an hour. I have no idea how much "rest time" would have been afforded the team; we're probably talking slaves here, so I'm guessing not too much, and there might have been a second team to take over during rest breaks, on an hour-on hour-off kind of thing. We don't know. If we can assume that at peak production an ancient mint could manage to get a strike rate up to 10,000 per day, that means that a typical coin die would last only two or three days - analysis of coin dies of surviving coins imply that a typical obverse die only lasted for about 20,000 coins, with reverse dies lasting even less.

For estimates of how many three-man teams might have worked in the mint simultaneously, we'd have to try and work out actual total mintages for the mint as a whole and make assumptions about how "busy" the mint was in terms of processing available raw metal into coinage - which for most years during the Roman period is little more than educated guesswork. Surviving financial records of the early Empire's budget do seem to indicate that for some years during the early Empire the total annual mintage was around 2 million denarii; a single three-man team making 10000 coins a day, working 200 days a year (the Romans didn't have "weekends" but did have lots of public holidays), could produce those 2 million coins a year, but then you'd also need more teams to make the gold and bronze coins. Precise mintage figures for Roman coins are unknown. The Romans no doubt kept meticulous mint records, but these have not survived. For the Late Empire period, it's probably reasonable that each "officina" or mint-house within a city might have held one three-man team each.

1000 coins/hr * 1 hr/3600 sec = 1 coin / 3.6 sec.

I agree, however, that's probably not sustainable pace for a whole day.

For what it's worth, if you fast forward to the late 15th century, we know from mintage records in the Low Countries that at the Antwerp and Bruges mints, quantities of around 500,000 per year each of two types were being produced. Taking into account the many Christian feast days in medieval times, I suspect we are talking about the same kind of math.

I wonder if anyone in modern times have used the three man team to test how many coins they could strike per hour.

Were silver blanks hot at the time of striking?

We don't have any unequivocal coin-minting hammers that have survived, so all we have to go on are (a) surviving hammers of various kinds, which may or may not be relevant, and (b) illustrations of the hammers in pictures of coin manufacturing.

For surviving hammers, the weight ranges from under 100g to over a kilogram; half a kilogram (two Roman pounds) seems like a typical blacksmith's hammer weight.

For images, this old thread has a collection of pictures of coins which are believed to depict coin-minting tools. The hammers all seem to be quite small:


The figures depicted holding the hammers in the above examples are all holding them one-handed, though the long handle implies they were actually held two-handed during the striking.