<P> Rio Tinto Diamonds operates three diamond mines: the Argyle Diamond Mine in Western Australia (100% ownership), the Diavik Diamond Mine in the Northwest Territories of Canada (60% ownership), and the Murowa Diamond Mine located in Zimbabwe (78% ownership). Together, these three mines produce 20% of the world's annual production of rough diamonds, making Rio Tinto the world's third - largest producer of mined diamonds . </P> <P> The diamond business unit's most advanced exploration project is the Bunder Project in District Chhatarpur, Madhya Pradesh, India, where Rio Tinto became the first foreign group to be granted a prospecting license there . Rio Tinto Diamonds generated 1% of revenues and earnings for Rio Tinto Group in 2008 . </P> <P> Rio Tinto Minerals is a diverse business group with mining and processing interest in borates, salt, and gypsum . Rio Tinto Borax, with main operations in California and another mine in Argentina, supplies nearly half of the world's annual demand for refined borates . The Minerals group is also majority owner of Dampier Salt, which produces over 9 million tonnes of salt and 1.5 million tonnes of gypsum annually from its three facilities in northwest Australia . Rio Tinto Minerals accounted for 6% of company revenues, and contributed 3% to earnings in 2008 . </P> <P> On 31 January 2010, the management of U.S. Borax locked out its hourly workforce, replacing the workers with nonunion workers and managers from other Rio Tinto operations . The 560 International Longshore and Warehouse Union Local 30 members immediately began a fireside vigil that garnered national and international labour attention . ILWU filed several unfair labour practices against the company, including an illegal lock - out claim . </P>

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