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 at the average rate of US$62.23, a volume that represented about 78 percent of the amount sold by the diamond companies around the country. The note states that as a result of the processing of the ore, the company obtained a total of 7.5 million carat that permitted to establish the operational costs. In 2012 the mine produced 6.5 million carats out of 10 million metric tons of ore production. The Catoca diamond deposit occurs in a kimberlite pipe. Catoca diamond mine The Catoca diamond mine is the fourth largest diamond mine in the world, and is located in Angola.