1981 Australian 20c piece
In 1981 the production of Australian 20c piece was performed by three mints - the Royal Australian Mint, the Royal Mint and the Royal Canadian Mint. The Royal Australian Mint had exclusively produced 20c pieces since 1967 but industrial action at the time resulted in the outsourcing of some coin production. Unfortunately, the outsourced coins did not get struck with mint-marks making it difficult to distinguish where exactly a coin was produced.
The Royal Australian Mint coins are no different to coins produced in other years like 1980 or 1982, and are also the most numerous, with 65,500,000 coins produced.
The Royal Mint coins are difficult to distinguish but on the reverse the platypus' nostrils are shallower and the first and second claws (closest to the platypus) beneath the 2 are somewhat shortened (p28-29, Bedogni and Roberts, The Reverse Dies of the 1981 20c piece in Australasian Coin and Banknote Magazine, August 2006). On the obverse the the Queen's eyebrows are less defined too (p61, Bedogni and Roberts, Differentiating the Dies of the Australian 20c Piece in Australasian Coin and Banknote Magazine, May 2006).
The Royal Canadian Mints are somewhat easier to distinguish - on the reverse the first claw (closest to the platypus) under the 2 is half missing (the so-called 3.5 claws) (p28, Bedogni and Roberts, The Reverse Dies of the 1981 20c piece in Australasian Coin and Banknote Magazine, August 2006) and on the obverse the legend is closer to the rim than the RAM coins (p61, Bedogni and Roberts, Differentiating the Dies of the Australian 20c Piece in Australasian Coin and Banknote Magazine, May 2006) and the legend also exhibits fish-tailing whereas RAM coins have flat-based letters. The Royal Canadian Mint coins also have more brilliant surfaces.
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