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
Catoca diamond mine Catoca diamond mine The Catoca diamond mine is the fourth largest diamond mine in the world, and is located in Angola. The mine is owned by a consortium of international mining interests, including Endiama (the state mining company of Angola) (32.8% ownership), Alrosa of Russia (32.8%), Odebrecht of Brazil (16.4%), and the Diamond Finance CY BV Group (16.8%). The mine is located on a kimberlite pipe. The mine had production of 1.8 million carats (360 kg) in 2000 and 2.6 million carats (520 kg) in 2001. Catoca management has been actively expanding capacity at the mine, such that the owners