KIMBERLITE " Blue Ground " - KIMBERLEY Mine (South - Africa) - Type Locality
Item History & Price
| Reference Number: Avaluer:5016334 |
KIMBERLITE KimberliteKimberley, South AfricaBig Hole mineIgneous rockBreccia*Blue GroundSpecimen is a 1.78g sliceCOMBINED SHIPPING : 5$ per package *Blue Ground : In reconnaissance for diamond mining, blue ground refers to a layer of non-oxidized kimberlite. Before the advent of modern geophysical probes, the ideal way to find a kimberlite pipe was to search for "yellow ground", a layer of oxidized kimberlite which is a deep tawny yellow. "Blue ground" was reg...arded with scorn during the South African diamond rushes. The geochemistry of Kimberlites is defined by the following parameters :Ultramafic; MgO >12%25 and generally >15%25Ultrapotassic; Molar K2O/Al2O3 >3Near-primitive Ni (>400 ppm), Cr (>1000 ppm), Co (>150 ppm)REE-enrichmentModerate to high large ion lithophile element (LILE) enrichment; SLILE = >1, 000 ppmHigh H2O and CO2 Kimberlite is an igneous 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 (16.70 g) diamond called the Star of South Africa in 1869 spawned a diamond rush, eventually creating the Big Hole.Kimberlite occurs in the Earth's crust in vertical structures known as kimberlite pipes as well as igneous dykes and sills. The consensus on kimberlites is that they are formed deep within the mantle. Formation occurs at depths between 150 and 450 kilometres, potentially from anomalously enriched in exotic mantle compositions (diamonds and garnet peridotite mantle xenoliths), and they 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.Its probable derivation from depths greater than any other igneous rock type, and the extreme magma composition that it reflects in terms of low silica content and high levels of incompatible trace element enrichment, make an understanding of kimberlite petrogenesis important. In this regard, the study of kimberlite has the potential to provide information about the composition of the deep mantle and about melting processes occurring at or near the interface between the cratonic continental lithosphere and the underlying convecting asthenospheric mantle. Check out my other items!WE COMBINE SHIPPINGPayment and ShippingI combine shipping, means you will pay only one time the S&H fees regardless the quantity in the package. Usualy you will pay a total of 2$ for all your items put together in one, or two packages.I accept Paypal or bank to bank transfer.If you have any question, please contact me.
