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 which explored the possibility of reopening it . Striker has since become North Australian Diamonds , a company which operated the mine for a short period in 2006. Rio Tinto originally acquired the mining lease after a takeover of Ashton mining (November 2000) in which it also gained full control of the Argyle diamond mine. Ashton mining initially developed and operated the 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