The Discovery of the Argyle Pipe, Western Australia: The World’s First Lamproite-Hosted Diamond Mine

Argyle diamond mine discovery is a tale of scientific exploration, belief, and persistence over a nine-year period from project formulation in 1971 to pipe discovery in 1979. Initial inspiration came from a suggestion that leucite lamproites that crop out in the Kimberley region of Western Australia were derived by differentiation from a kimberlite-like peridotite magma. A 200,000-km2-wide program of reconnaissance stream sampling was initiated in the north of Western Australia and discovered kimberlite indicator minerals and diamonds in three parts of the Kimberley basin and adjacent King Leopold and Halls Creek orogens. An innovative laboratory was constructed for indicator mineral recovery, and the use of chromite as an indicator was pioneered and proved a key mineral. Follow-up of indicator/diamond anomalies led to the world’s first recognition of olivine lamproites. The program led to the discovery of the smaller-scale Ellendale lamproite diamond deposit en route to finding the tier 1, high-grade Argyle pipe, the world’s first economic olivine lamproite-hosted diamond deposit, which has produced >750 million carats since 1983. Prior to these discoveries, traditional targets for diamond pipe exploration were areas of ancient cratonic basement. The Argyle and Ellendale deposits lie within the Halls Creek and King Leopold orogens, respectively, over thrust upon ancient cratonic lithosphere. The discoveries thus introduced a new target rock, olivine lamproite, for diamond exploration in nontraditional orogen environments.