The Argyle diamond mine is located in the Kimberley region in the Australian state of Western Australia. The Argyle mine is the first commercial diamond mine dug along a olivine lamproite volcanic pipe rather than a kimberlite pipe. The Argyle volcanic pipe is a diatreme formed by gas or volatile explosive magma which has breached the surface to form a "tuff" (consolidated volcanic ash) cone. The Argyle mine also has alluvial mining operations.
The Argyle mine is the largest raw diamond producer in the world, but a low percentage of its yield (around 5%) is gem-quality. The worldwide average yield of gem-quality diamonds is around 20%. The remaining 95% of Argyle's production is classified as "near gem quality" and "industrial grade".
Arglye is owned by Anglo-Australian mining titan, the Rio Tinto Group (60% ownership), which also owns stakes in the Diavik Diamond Mine in Canada and the Murowa diamond mine in Zimbabwe. Ashton Mining has the remaining 40% ownership. In 1996 Argyle turned the De Beers distribution monopoly on its head by going-it-alone, bypassing De Beers' Diamond Trading Company DTC/Sightholder wholesale network, selling directly to the Antwerp diamond trade.
Australia's Argyle pipe diamonds are approximately 1.5 billion years old, while the volcano which created the pipe is around 1.1 billion years old. This 400 million year gap represents a relatively short period for diamond formation. The short gestation period could explain the small size and unusual physical characteristics of these diamonds.
The mine produces 80% brown diamonds, 16% yellow diamonds, 2% white diamonds, and the remaining 1% are pink or green. Argyle diamonds fluoresce blue or green under ultraviolet light and the most common inclusions are graphite, crystalline orange garnet, pyroxene, and/or olivine. Most notably, the carbon found in Argyle diamonds mostly organic in origin.
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