Kimberlites and lamproites Until 1870, diamonds were found only in placer deposits, but then an area rich in diamonds was found at Kimberley in South Africa. The diamonds were embedded in a volcanic rock formation that came to be called kimberlite Although rare, diamond- bearing kimberlites have now been found on all continents, and diamonds have also been found in similar rocks called lamproites. Kimberlites are narrow, carrot-shaped volcanic vents or pipes that carry up volcanic material at amazing speeds from depths of 150km/92 miles or more. The basic magma is olivine-rich peridotite, but it is full of a host of other fragments that it sweeps up from great depths - including ready- made diamonds that are not only incredibly old but often contain minerals that have come from the core-mantle boundary 2,750km!1 ,709 miles down. Samples from kimberlite mines are beginning to give geologists a fascinating insight into the Earth's interior.
Kimberlites and lamproites Until 1870, diamonds were found only in placer deposits, but then an area rich in diamonds was found at Kimberley in South Africa. The diamonds were embedded in a volcanic rock formation that came to be called kimberlite Although rare, diamond- bearing kimberlites have now been found on all continents, and diamonds have also been found in similar rocks called lamproites. Kimberlites are narrow, carrot-shaped volcanic vents or pipes that carry up volcanic material at amazing speeds from depths of 150km/92 miles or more. The basic magma is olivine-rich peridotite, but it is full of a host of other fragments that it sweeps up from great depths - including ready- made diamonds that are not only incredibly old but often contain minerals that have come from the core-mantle boundary 2,750km!1 ,709 miles down. Samples from kimberlite mines are beginning to give geologists a fascinating insight into the Earth's interior.
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