Argyle diamond mine at the Ekati mine, both in Canada. However, Argyle has two to four times the concentration of diamonds (ore grade) of these mines. This makes extraction economically feasible, as mine costs are mostly related to the amount of ore processed, not the amount of diamond extracted. In 2005, Rio Tinto was given the go-ahead to a future expansion project, moving it from an open pit to an underground mine. This plan was postponed; in September 2010 Rio Tinto announced fresh plans to develop an underground mine beneath the existing pit, increasing annual production to 9 million tonnes of ore. The
Merlin diamond mine Merlin diamond mine The Merlin diamond mine is one of only three diamond mines in Australia. The mine is located in the Northern Territory of Australia, about 80 kilometres south of Borroloola. The mine operated for a period of about four years from 2000 to mid-2003, during which time it produced about 500,000 carats (100 kg) of high quality diamonds. The Merlin mine has an unusually high proportion of gem-quality diamonds: 65% of production is gem-quality, and only 35% is classified as near-gem or industrial quality. This compares to a worldwide average of just 20% gem-quality diamond production at diamond