The Australian tenth-ounce platinum piece (abbreviated as 1/10 oz and designated with Pt for "Platinum") 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.
The overall weight of the coins is slightly over a tenth ounce, so as (accounting for the purity of the alloy) to have exactly 0.100 ounces of platinum content. | 
