Australia is one of the large issuers of bullion coins. Uniquely, there are two independent mints in the country 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. Their issues are normally in standard sizes (mostly based on the troy ounce), but sometimes they also issue coins in non-standard formats, such as this one
This coin is part of the Australian Wedge-tailed Eagle series by the Perth Mint, and the fourth design by John M. Mercanti (the series features a new design every year).
The Mint says about it:
"Crafted from two of the most ‘noble’ precious metals, gold and platinum, this innovative coin is a numismatic masterpiece portraying John M. Mercanti’s soaring Wedge-tailed Eagle design in an intriguing 1.5oz format.
The second of its kind from The Perth Mint, the coin combines a centrepiece containing 3/4oz of fine gold and an outer ring made from 3/4oz of pure platinum. Bonded together during the striking process, their fusion results in a brilliant bi-metal release of spell-binding beauty - the perfect canvas on which to showcase American coin designer extraordinaire John M. Mercanti’s fourth design for The Perth Mint.
The coin’s pure gold centrepiece depicts a magnificent wedge-tailed eagle in flight with wings fully extended and stylised rays of sunlight in the background."