1992 Australian 20 Cents Struck With Bolt

This is so cool! Pretty amazing error.

Sigh--that won't fit into any Dansco I have.

You'll just have to get that entire display then.

This one is actually on permanent display in the public gallery at the Royal Australian Mint, which shows off a quite impressive selection of spectacular mint errors - the kind that aren't likely to sneak out of the mint in a bag with the rest of the coinage, such as this example. It makes a nice change from back in the day when Mints hid their mistakes away from the public eye.

They also have a couple of blank-feeder arms that got smashed by a coin die, leaving a coin-shaped dent in the steel disc:



For the bolt-coin, the display's blurb implies that the presses were moving at high speed. But this coin is clearly a proof coin - so the presses would have been moving much slower (but at much higher pressure) than the circulation presses.

I don't think it's "mint sport" - that would have been a highly expensive sport, given that the proof dies would have been totally destroyed by this incident and would have needed replacing. Not to mention dangerous; a random piece of steel shoved into high-pressure coin dies could explosively shatter, and shards fly about the place at high speed. I think it was a genuine industrial accident, as the Mint claims, a bolt falling off the upper machinery and happening to land in the presses as a coin was being struck. It's just that the timing wasn't quite as coincidental, or the process as automated, as the blurb implies it to be. The RAM's proof coin presses are manually operated; the blanks are placed and the finished coins removed by hand, by the technician operating the press (a process clearly visible if one is visiting the Mint during proof coin production hours).

My picture is from the old display they had up when I first visited, in 2009. The OP pics are from the current display, where you can see both sides of each piece. The same "bolt coin" is in both displays.

Ok yep sorry about misunderstanding your point @sap. Considering the care with which proof coins are struck, I'm personally struggling to see how this was an accident, but it's impossible to know for sure.