When geologists discovered diamonds in the Kimberley region in the 1970s, they were expecting to find them in the traditional diamond-bearing ore, kimberlite. In fact, the diamonds in the Kimberley region were found in lamproite ore. This was unique to the diamond world at that time and Argyle remained the only economically viable lamproite diamond mine for many years.
The Kimberley diamond region consists of a central core of a thick series of nearly flat-lying sedimentary and volcanic rocks that were deposited between 1.6 and 1.9 billion years ago. These rocks form the Kimberley Plateau. They are underlain by a basement of crystalline igneous and metamorphic rocks, which are not exposed on the surface of the plateau. Recent investigations have indicated that the basement is of Archaean age, that is, more than 2.5 billion years old.
The future of mining at Argyle, and plans for the development of an underground mine beyond 2010
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