As I mentioned in my first post, I am a Newbie! So my question probably made many of you role your eyes. But I genuinely do not understand why so many ancient coins (focusing mostly on tetradrachms) are struck off-center.
From the little research I've done, it seems the blank was placed in some type of slot/opening, which held it in place. And when the coin was struck, both sides of the coin receive the design.
At first I thought the obverse die was placed over the blank, then struck. Then the blank was flipped over and the reverse die was placed over the blank and struck. While this is likely a rather pedestrian and elementary-school way of understanding the process, to my simple mind this would explain why coins were struck off-center, because they weren't held in place.
Someone please explain it to me like I'm a six-year-old!!
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Some ancient coins were cast in a mold. I have a few small ancient Jewish coins called lepton that were cast. I think most anceint coins were individually struck with a hammer, the lump of metal (called blank or planchet) was heated, placed between an obverse die and a reverse die then the top die was hit with a hammer to create the coin. It's not a precise methed, the metal or die could shift causing off center strikes, doubled strikes. Off center, doubled strikes and other errors can happen with modern coins too in the striking chamber of presses. See below my 1994 off center cent.
Anceint artisans carved the coin dies. There's been a few ancient dies found but they are rare. When the dies became worn they were destroyed so forgers could not use them. Below is a pic of an ancient die of Tiberius Caesar sold at a CNG auction some years ago for $50,000. Sometimes modern coin dies can be purchased. A few times the US Mint has sold coin dies to the public but their surfaces were mostly defaced so they can't be used.
I found several YouTube videos about how anceint coins were made, here is a pretty good one.
Thanks! The Tiberius die is crazy cool! What a find!
So if the youtube video above is accurate, it would appear the people doing the striking of the coin just got lazy when placing the blank or were in a hurry, leading to miss-struck coins.
Maybe there were daily production numbers to make, quantity over quality. I don't know if anyone has ever tried to calculate the percentage of ancient coins struck off center. In my opinion many ancient coins are pretty well center struck considering the manual methods used.
Sometimes a coin wasn't struck off center, the blanks were a little too small for the dies. Dealers will sometimes describe such coins as struck on a small flan. This happened with the massive production of Athens silver tetradrachms made for roughly four hundred years. The style of the design changed over time. Many of them have the crest of Athena's helmet missing or Athena's tip of nose missing. On the reverse the owl's feet may be missing or some of the letters missing. Below is one of my Athens owls showing this. I have no clue why they were made this way, guessing quantity over quality.
In short, ancient (and mediaeval) coins are frequently struck off-centre because, unlike modern mint machinery, there was no device or collar aligning the coin blank with the dies. Everything was done by hand. And coins are only ever struck just the once - If you tried to strike a coin one side at a time, the second strike would flatten and obliterate whatever design had just been placed in the first strike.
Consider the day to day operation of a hammered coin mint. Striking coins by hand is typically a three-person operation: one guy to put the blanks down on top of the obverse die (which would have been set into an anvil), one person to manually place the reverse die on top of the blank and hold it steady with his hands, and a big guy with a hammer to smash the entire assembly together with a single blow. The second guy would then pull away his die, and the first guy would swoop in, grab the minted coin to toss into a basket of finished coins, and replace it with a fresh blank for the next strike. This is of course complicated in the case of bronze coins, as cold bronze is too hard to take a design with a single hammer-blow so the blanks had to be heated before striking and the first guy needs to use tongs to get the coin in and out.
You would want the team to quickly get into a rhythm, with the big guy with the hammer calling the shots in terms of timing - you don't want someone's hand in the wrong place when the hammer comes down next, or they're gonna lose it. There simply isn't time to stop and make sure everything's all nicely lined up; the first guy only has a second or two to put the blank down straight, and the second guy also only a couple of seconds to get the hand-held die lined up on top of the blank.
And "near enough is good enough", in most cases - they're certainly not going to go to the trouble of melting down and re-striking a coin just because it's off-centre a bit. If most of the emperor's name and portrait was there, and most of the message on the reverse, then it's mission accomplished for the mint workers for that coin. If a coin were so severely off-centre, that the emperor's portrait was defaced or missing, that might be cause for rejecting the coin - assuming anyone stopped to actually notice. There would have been some kind of supervisor, the "moneyer", overseeing the operation, making sure coins weren't being pocketed and doing rudimentary quality control checking. During certain time periods such as the Roman Republic or 12th century England, we even know that supervisor's name, as he put his name on the coins.
The hand-held nature of the reverse die also explains why ancient coins are very often struck with random die alignments. The chisel-like reverse die didn't normally have a "this way up" marker. Consistent die alignment is really only possible with machine-struck coinage.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
A measured volume of silver or gold was poured out on a surface to form a strip of 8 cobs. Without using a scale, the cooled strip was divided by sequentially balancing it and chopping it to make the planchets (which are usually within 1-2% of correct weight). The planchets were struck with a hammer, sometimes more than once. No time was wasted because there was a huge amount of metal to process. Spanish cobs are as crude as the most primitive 500 BC coinage from Mysia and Lydia. Judging from the high quality of most of the images, the dies were well engraved, but the fast-working coin and planchet makers weren't finicky about the quality of their product.
The "planchets" for the early Lydian and Mysian coins I have are irregular lumps of metal squashed by the coin striker's hammer. They aren't flat and the edges are often cracked. In reference to Sap's comment, the earliest coin reverses were made on a chisel-like support instead of a die, sometimes leaving a swastika-like pattern.
"Two minutes ago I would have sold my chances for a tired dime." Fred Astaire
Quote: In short, ancient (and mediaeval) coins are frequently struck off-centre because, unlike modern mint machinery, there was no device or collar aligning the coin blank with the dies.
That makes a lot of sense. In principle, if everything "fits," that is, the blank is nearly exactly the inside diameter of the lower die, likewise the upper die, then coins should be well centered. But as soon as the blank does not fit snugly, and/or the upper die does not, there is the opportunity for off-center outcome.
Quote: 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.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
1000 coins/hour would be a coin struck every 0.27s. That doesn't sound right for three humans. I would guess that a rate of maybe one coin every 5-10 seconds could be sustained for periods of time, but that's tremendous effort for the hammer swinger.
Quote: 1000 coins/hour would be a coin struck every 0.27s.
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.
1000 coins an hour would be about 16 coins a minute, or one coin every 3.6 seconds - so not too far off your estimate. And yes, that's an absolute peak maximum production rate which could not actually be sustained by three people for an hour, let alone for a whole day.
Further reading on the operational structure within a Roman mint, I found a website which not only shows a couple of ancient Roman medals depicting the three-man scene within a mint, but also lists a ruined plinth excavated from the Roman forum, dating from AD 115, which appears to list all of the workers in the Roman mint at the time: 25 officinatores (officials and administrators), 39 malliatores (hammer-men), 11 suppostores (the guys who placed the coin blank under the die), and 17 signatores (reverse-die-holders). A total of 93 workers, of which 48 were freedmen and 45 were slaves. Note: the actual die-engravers (called "scalptores" in other sources) aren't listed, so the die workshop must have been considered a separate institution from the Mint.
That hammer-men outnumber the other two guys by over 3:1 indicates the hammer-men must have been frequently rested while the other guys continued their shift.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
Doh. My mathematical mistake. It's 0.27 coins/second, which is a nonsensical stat because it's inverted. Since they are minting complete coins, you want s/c not fractional c/s. 1/27 is indeed about 3.6s per coin.
Still pretty fast on the hammer to sustain that for any length of time. How big was the hammer to strike those coins? It must have had heft to drive the design that deeply.
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Posted 02/11/2025 1:55 pm
