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
Letlhakane diamond mine Letlhakane diamond mine The Letlhakane diamond mine is a diamond mine located in Botswana about west of the city of Francistown. Letlhakane, meaning "little reeds", is owned by Debswana, a partnership between the De Beers company and the government of Botswana. It is the second oldest of four mines operated by the company, having begun operations in 1975. Letlhakane is of open pit construction. In 2003, the mine produced 1.06 million carats (212 kg) of diamond. The recoverable ore grade at the mine was about 0.26 carats (52 mg) per ton. The ore produced at Letlhakane used to be processed