The Australian one-ounce gold piece (abbreviated as 1 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 a series by the Perth Mint featuring Mythical Creatures and portrays a Chimera.
The mint says about it:
In Greek mythology, the chimera is a fantastical creature that embodies the fearsome qualities of various animals. The chimera's hybrid nature makes it a symbol of the unnatural, the discordant blending of different species into one entity, defying the natural order. In literature and art, it is often used to represent wild imagination and chaos, serving as a metaphor for the unpredictable and uncontrollable forces in the world. | 
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