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
Williamson diamond mine the future. The mine was equipped with a range of sporting facilities. These included public swimming pool, tennis and squash courts, soccer field, athletics track, golf course and yacht club. There was also a surgical hospital staffed by two English and an Indian doctor and nursing staff. The hospital used to treat the mine employees for free, and poor people from neighbouring areas could take treatment there at nominal charges. These facilities fell into disrepair after the colonial era, but remain partly maintained by the mine. Williamson diamond mine The Williamson Diamond Mine (also known as the Mwadui mine) is