The Australian ten ounces silver piece (abbreviated as 10 oz and designated with Ag for "silver") 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 third design by John M. Mercanti (the series features a new design every year).
The Mint says about it:
"A Perth Mint first with master of avian design, John M. Mercanti takes a touching look at the life-cycle of Australia’s largest bird of prey for his third design in this majestic series in a spectacular 10oz size. The exceptional coin portrays a mother Wedge-tailed Eagle tenderly looking down on her chick. A protective male bird is portrayed hovering above them with its magnificent wings fully extended.
An extra thick blank and deeply engraved dies are required to press this special kind of release. The finished coin features a slightly concave table with an appreciably raised relief showcasing the design in spectacular style." | 
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