Kimberlite (rare Colorado loc.) James Howard Coll.

Item Description

Kimberlite specimens from the diamond-bearing kimberlite diatremes of Colorado's State Line District are rare. Diamonds and diamond kimberlite indicator minerals are occasionally on the market from here and are highly desired by Colorado collectors. Kimberlite is an igneous rock best known for sometimes containing diamonds. Kimberlite occurs in the Earth's crust in vertical structures known as kimberlite pipes as well as igneous dykes and sills. Kimberlite pipes are the most important source of mined diamonds today. The consensus on kimberlites is that they are 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 they are erupted rapidly and violently, often with considerable carbon dioxide and other volatile components (Wikipedia). Numerous xenoliths or fragments of other rock/mineral types are visible in the kimberlite matrix. Ex James Howard Collection.