Kimberlite – an igneous rock best known for sometimes containing diamonds. It named after the town of Kimberley in South Africa, where the discovery of an 83.5-carat diamond in 1871 spawned a diamond rush. About 6,400 kimberlite pipes discovered in the world. Of those about 900 classified as diamondiferous, and of those just over 30 economic enough to diamond mine.

Kimberlite occurs in the Earth’s crust in vertical structures known as kimberlite pipes as well as igneous dykes and sills. Today it is the most important source of mined diamonds.

The consensus on kimberlites is that they formed deep within the mantle. Formation occurs at depths between 150 and 450 kilometres (93 and 280 mi), potentially from anomalously enriched exotic mantle compositions, and erupted rapidly and violently, often with considerable carbon dioxide and other volatile components. It is this depth of melting and generation which makes kimberlites prone to hosting diamond xenocrysts.

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