The Australian five ounces gold piece (abbreviated as 5 oz and designated with Au for "gold") is a bullion coin format. Uniquely, in Australia there are two mints authorised to strike legal tender: the Royal Australian Mint (which also makes the country's circulating coinage) and the Perth Mint which only makes collector and bullion coins, as well as other bullion products.
Both mints endeavour to create coins with attractive designs, and to introduce new designs and themes often, in order to raise the numismatic value of the coins over the value of previous metal used.
This coin is part of the Australian Wedge-tailed Eagle series by the Perth Mint, and the second design by John M. Mercanti (issued in 2016 and 2017 only).
The Mint says about it:
"One of Australia’s most incredible birds is captured on this spectacular 5oz gold high relief coin featuring an original design by American sculptor and engraver, John M. Mercanti. The coin’s high relief reverse and obverse are minted on concave surfaces to ensure the optimum flow of metal is achieved by the strike of the die." | 
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