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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 and led to the excavation of the open-pit mine called the Big Hole. Previously, the term kimberlite has been applied to olivine lamproites as Kimberlite II, however this ...
In diamond, all the carbon-to-carbon bonds, both within a layer of rings and between them, are in the staggered conformation, thus causing all four cubic-diagonal directions to be equivalent; whereas in lonsdaleite the bonds between layers are in the eclipsed conformation, which defines the axis of hexagonal symmetry.
There are a limited number of commercially available diamond mines currently operating in the world, with the 50 largest mines accounting for approximately 90% of global supply. [1] Diamonds are also mined alluvially over disperse areas, where diamonds have been eroded out of the ground, deposited, and concentrated by water or weather action.
The grade of a typical heavy mineral sand ore deposit is usually low. Within the 21st century, the lowest cut-off grades of heavy minerals, as a total heavy mineral (THM) concentrate from the bulk sand, in most ore deposits of this type is around 1% heavy minerals, although several are higher grade.
[20] [21] Perthite is a typical texture in alkali feldspar, due to exsolution of contrasting alkali feldspar compositions during cooling of an intermediate composition. The perthitic textures in the alkali feldspars of many granites can be seen with the naked eye. [ 24 ]
The Jwaneng Diamond Mine is situated within the Orapa Kimberlite Field. [14] In the mine lies the "Jwaneng pipe," [15] a volcanic crater formed during the Permian period. [16] The mine consists of three kimberlite pipes. [17] Diamond-bearing ores are extracted from the vast pit and transported to processing facilities and manufacturing ...
Phaneritic rock: Anorthosite from the Stillwater Igneous Complex (Neoarchean; Montana) Igneous textures include the rock textures occurring in igneous rocks.Igneous textures are used by geologists in determining the mode of origin of igneous rocks and are used in rock classification.
On 21 September 2008 Gem Diamonds, Ltd. announced that it found a 95.6 grams (478 carats) diamond of high quality, making it the 20th largest diamond ever found. It is a type II D colour, with potential to yield a 30 grams (150 carats) cut stone.