Kimberlite (Bellsbank Kimberlite, Early Cretaceous, 118 Ma; Bellsbank Mines, near Mount Rupert, north of Kimberley, South Africa) 4 : 無料・フリー素材/写真
Kimberlite (Bellsbank Kimberlite, Early Cretaceous, 118 Ma; Bellsbank Mines, near Mount Rupert, north of Kimberley, South Africa) 4 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Kimberlite from the Cretaceous of South Africa. (6.6 centimeters across at its widest)Kimberlites and lamproites have tremendous economic importance because they are host rocks for gem-grade and industrial-grade diamonds. Kimberlites & lamproites are unusual igneous bodies having overall pipe-shaped geometries. Their mode of formation is only moderately understood because they have not been observed forming. Kimberlites & lamproites are known from scattered localities throughout the world - only some are significantly diamondiferous. Classic localities for diamonds are India and Brazil. Africa was also discovered to have many kimberlites and is world-famous for producing large numbers of diamonds. Other notable diamondiferous kimberlite-lamproite occurrences include Russia, China, northwestern Australia, and northwestern Canada. Kimberlites are named for the town of Kimberley, South Africa. Several kimberlite pipes occur in the Kimberley area. Kimberlites have a gently tapering-downward, pipe-shaped cross-section. Lamproites have a cross-section more closely resembling that of a martini glass.This is a sample from South Africa’s diamondiferous Bellsbank Kimberlite. It has a typical kimberlite appearance: a jumbled mix of crystals and clasts. Serpentinized and partially serpentinized olivines with dark greenish-gray reactions rims are common and conspicuous. Scattered phlogopite mica and garnet are also present. The Bellsbank Kimberlite intruded through Proterozoic-aged dolostones of the Ghaap Group during the late Early Cretaceous (Aptian Stage, 118 Ma).Locality: Bellsbank Mines, near Mount Rupert, north of Kimberley, north-central South Africa |
| 撮影日 | 2020-12-18 01:29:33 |
| 撮影者 | James St. John |
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