Argyle diamond mine of tunnelling, the Argyle underground block cave development was officially completed. In 2013, Argyle is estimated to produce 10.2 million carats with an average per carat price of $25/carat. The Argyle diamond mine is also notable for being the first successful commercial diamond mine exploiting a volcanic pipe of lamproite, rather than the more usual kimberlite pipe; much earlier attempts to mine diamonds from a lamproite pipe in Arkansas, USA were commercially unsuccessful. The Argyle mine is owned by the Rio Tinto Group, a diversified mining company which also owns the Diavik Diamond Mine in Canada and the Murowa Diamond
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