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
Hugo Dummett on a "shoestring," staked some promising ground near Lac de Gras in 1989. Dummett took a new job with BHP Minerals in 1989, and convinced his new employer to lease their property. In 1991, BHP drilling on their leased claims found micro-diamonds, sparking one of largest claimstaking rushes in mining history. Under Dummet's direction, BHP eventually developed commercial diamond reserves in five pipes; the discovery pipe turned out to be non-commercial. BHP began the permitting process for the Ekati Diamond Mine in 1995, received final approval in 1997, and opened the mine late in 1998. By 2009, annual sales from