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January 13, 2010
Error Coins on Display at The Royal Australian Mint
The Royal Australian Mint in Canberra displays a wide range of coins in their museum on the first floor of the newly refurbished building. Amongst the coins on display is a variety of error coins or mistakes that have happened to coins during production. We're lucky to have some of these coins on display because it's quite rare that coins of this nature would pass by the strict quality control to exit the mint and enter circulation.
The 20 cent proof shown below is one of those coins that jammed the machine and was never capable of exiting the press. One of the feeder fingers which feeds the blanks into the press has malfunctioned and the pressures of the strike have welded the feeder finger to the coin. The press would have needed to be dismantled to fix this coin jam.
Major whoops 20c ProofThe Australian commemorative dollar shown below is termed a "die cap". It failed to be released from the press, adhering to the upper hammer die. It was this "capped" coin that struck the subsequent coins. The blanks fed through while the cap was in place struck on this die cap and would exit the press as brockage errors showing the mirror image of the design on the reverse. The more brockage errors the die cap strikes the higher and deeper the cap becomes before breaking from the hammer die.
2009 Citizenship $1 Die Cap ErrorWe've spoken before about double struck coins and this example is a beautifully toned magnificent example of a double struck 10c. A struck coin failed to eject from the press completely and was struck for a second time. This produced an elongated planchet with half of the coin design depicted twice.
10c Double StrikePosted by harrisk at January 13, 2010 4:41 PM
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