A Question About Struck Through Errors.

My 900th post goes to wrekkdd!

I would think any foreign object on the die to produce a struck-thru error would leave some kind of impression especially a harder chunk like metal, but I think I see what you are getting at. If a large enough foreign object gets into the minting area, conceivably the die itself could break off and become its own strike thru...

I imagine in any case it would be labeled as die damage or Die Deterioration as it would probably be impossible to tell the difference. I'm not sure what burnishing beads are made from but there is examples of coins struck through them(I think that's what they are called) but I wonder if a die that struck something like that would leave a raised impression on a coin that could be seen on many coins.

I would think that chips on the surface of a die could often be the result of a strike thru scenario involving something hard being caught between the die and planchet during a coin's striking.

The hard item could chip the die before falling away and cause the struck coins that follow to exhibit a die chip error (raised area on coin). Die chip errors are relatively common errors.

Yes, in other words, a type of die chip.

In order to impress the coin design onto a blank piece of metal, not just once but tens of thousands of times, coin dies have to be both hard and tough. The dies are the hardest and toughest objects likely to be flying around in the mint presses. Unlike a coin, they're deliberately designed not to deform under pressure. To deform a working die, you'd need (a) an object much harder than a coin die, (b) pressures much higher than regular operating pressures, and (c) a compression time much longer than normal. Which wouldn't be a "mint error", it'd be someone illegally and dangerously fooling around with hazardous machinery.

Suppose you can find a foreign object that's large enough to leave a visible impression yet tough enough to cause damage to the die, and you insert it into an operating coin press, without a coin blank in place (as the presence of a coin blank will simply create a regular "struck through" error coin). It will likely shatter either the object or the die. If it's the object itself that shatters, you might get die chips, and you'll highly likely have other damage to the press from bits of hardened metal flying about the place, but you won't get a nice clear object-shaped indentation in the die. The laws of physics simply don't allow it. And if it's the die itself that shatters, well, I suspect the "shattered die" mint error phenomenon is usually caused by just such an event occurring.

The thing with die clashes in particular is that both sides are dies, and thus roughly equally hard, so "will shatter either the object or the die" does not apply: the force is spread evenly(ish) on both sides and deforms both.
Sometimes one (or both?) of the dies is indeed broken during the clash; the cases where one of the dies breaks and has to be replaced are probably how you get one-sided die clashes.

I think I've also seen (especially on older coins) some die chips that were just there in the middle of the field; those could have been caused by just this type of deformation.

When you first mentioned a die strike through I thought you meant a strikethrough that occured during the hubbing of the die. those exist as well. The 1952 "superbird" proof quarter and the 1965 "5 on cheek" are examples of dies hubbed through a piece of lint that was then impressed into the die.

The other thing with die clashes is that, unless there's been a major malfunction with the press, the dies are not hitting each other at full pressure. Modern coin presses have stops and restraints in place to try to prevent full-impact die collisions, in the event of a missing blank. A foreign object placed between the dies would be struck at full speed, making "shattering" rather than "deforming" much more likely.

I also suspect that modern die clashes are generated from multiple impacts between the dies, rather than just one. A whole bunch of smaller, low pressure impacts is more likely to create deformity than a single powerful blow.

It is interesting to see the example from 1804. I would expect such an event to be more likely on older minting machinery, when dies were less hard and presses operated at slower speeds.


Technically, all coins that result from damaged/altered/changed dies are "varieties", rather than "errors", which are caused by a fault or failure in the minting process. The terminology is getting mixed up these days, especially on ebay etc where there's the perception that "errors" must be worth more money.

And, as you can see, this type of event is so rare (I would still maintain that, for modern coin machinery, that "rarity" would become "practically impossible"), that when it happens, there isn't a "generic" name for it, other than "damaged die". Perhaps "die damaged by foreign object", if you want a generic category. Collectors would then give the resultant coins a name derived from the appearance of the flaw - such as "spiked chin" or "superbird".