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Kimberlite |
  
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Kimberlite |
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This rock is fine-crystalline, non-equigranular to porphyritic and consists of olivine, serpentine, garnet, ilmenite, pyroxene, calcite and magnetite.
Kimberlite is a type of potassic volcanic rock best known for sometimes containing diamonds. It is named after the town of Kimberley in South Africa, where the discovery of an 83.5 carat diamond in 1871 spawned a diamond rush, eventually creating the Big Hole. Kimberlite occurs in the Earth's crust in vertical structures known as kimberlite pipes. Kimberlite pipes are the most important source of mined diamonds today. The general consensus reached on kimberlites is that they are formed deep within the mantle, at between 150 and 450 kilometres depth, from anomalously enriched exotic mantle compositions, and are 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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