The Perth Mint is Australia's oldest currently operating mint (with the earlier mints, the Sydney Mint and Melbourne Mint having since shut down). After the foundation stone was laid in 1896 by Sir John Forrest, the Mint opened on June 20, 1899 as a branch of the Royal Mint in London to refine gold and manufacture gold sovereigns and half sovereigns to be used as currency in the colony. At that time, Western Australia's population was growing rapidly (23,000 in 1869 and 180,000 in 1900) due largely to the discovery of gold in the Kalgoorlie, Coolgardie and Murchison areas of the colony. There was very little money available in Perth for which miners could exchange gold to pay for goods. Although Federation occurred in 1901, the Mint remained under the jurisdiction of Britain until July 1, 1970, when it became a statutory authority of the Government of Western Australia. It is now owned by Gold Corporation which is wholly owned by the Government of Western Australia. Up to 2000, the Mint's refined gold output totalled 4,500 tonnes, representing 3.25% of the total weight of gold produced by humankind. This is about the current holdings of gold bullion in the United States Mint's Fort Knox Bullion Depository. Up until the end of 1983, the Perth Mint also manufactured much of Australia's lower-denomination coin currency. Today, the Mint continues to provide refining and other services to the gold industry and manufactures many coin related numismatic items for investors and coin collectors. It is responsible for manufacturing and marketing most of Australia's legal tender precious metal coins, including proof quality Australian Nugget gold coins, Australian Platinum Koala coins, Australian Silver Kookaburra coins and bullion.