Above you can see one of the most spectacular errors to come out of the Royal Australian Mint since the Australian 20c and dollar coins struck on bi-metal planchets. Or perhaps an error by the Royal Mint accidentally striking Australian 20c on Hong Kong scalloped planchets back in 1981. This coin above is truly a one in a million, or perhaps one in 50 million or even a billion. Falling from a mint roll this coin is absurdly wrong for an Aussie 20 cent piece. Firstly it’s the wrong shape, our coins are round right? Yes, this coin is triangular! Next it’s the wrong colour, appearing aluminium bronze like our one and 2 dollar coins and not as a cupro-nickel 20 cent should. Not like any of the other coins in the roll.
That’s because the Royal Australian Mint in Canberra has made a terrible mistake…….
A planchet intended to become a Cook Islands 2 dollar coin has accidently got mixed up in the barrel of blanks intended to strike Australian 20c cents. This error is not improbable as the Mint struck $2 coins for the Cook Islands dated 2015 over the past few years. What an incredible error coin though to find for just 20 cents! Technically though it is an Australian 20c, but worth a lot more to coin collectors. This coin error is known as a wrong planchet error, foreign planchet error and off-metal planchet error, what a stunning coin.
Update 14 December 2017
This coin appeared in the Universal Coin Company December live auction where it sold for AUD$9600 plus AUD$1440 buyers premium.