Kimberlite rocks

Figure 6.119 shows a sample of garnet lherzolite that was carried to the surface in a South African kimberlite pipe. The garnets are red, olivine and orthopyroxene are green, and the less common emerald green grains are clinopyroxene. ... Many ultramafic rocks – including those in kimberlite nodules – have been altered so much that we ...

The Archean rocks are invaded by granites of various age and by numerous smaller in- trusives of varied composition. The Archean is divided in two systems: the ...Rare volcanic rocks known as kimberlites are produced from magmas that originate in Earth’s mantle and then erupt onto the planet’s surface. These rocks have a violent eruption style, and a...Here kimberlite is used as an example of the subdivisions: (1) volcaniclastic kimberlite (VK), i.e., fragmental rocks, and (2) coherent kimberlite (CK), typically, non-fragmental intrusive rocks. With more detailed information, these two fundamental root rock names can be further subdivided: massive volcaniclastic kimberlite ...Kimberlite is a type of igneous rock that is ultramafic and ultrapotassic. Its mineral content usually includes olivine, phlogopite, pyroxene, and garnet, accompanied by a variety of trace minerals. Kimberlite occurs in the Earth 's crust in vertical structures known as kimberlite pipes. These pipes are the most important source of mined ...KIMBERLITE AND RELATED ROCKS 11 petrology. Similar megacrysts are common in alkali basalts, nephelinites, and alnoites (see Chapter 6), and in these parageneses the megacrysts are commonly considered to be high-pressure phenocrysts. Regardless of their origin, the me­ gacrysts, as found in kimberlite, have distinctive compositions and the ...Kimberlite eruption, small but powerful volcanic eruption caused by the rapid ascent of kimberlites—a type of intrusive igneous rock originating in the asthenosphere—through the lithosphere and onto the surface of the Earth. Kimberlites are thought to rise through a series of fissures in the rock.

rocks. The pipes probably erupted at the surface when they were formed and were then marked by an open crater and a small cone of ejected material. In al­ most all cases. however. subseq uent ero­ sion has removed the surface features and the uppermost strata of both kimberlite and the surrounding rocks. The pipes now available for study areArndt et al. (2010) and Cordier et al. (2015 ) suggest that olivine ‘nodules’ in kimberlites are produced by metasomatism of peridotite wall-rocks by proto-kimberlite …Rocks with hardness 1-3 are soft rocks from 3-6 are medium hardness rocks and 6-10 are hard rocks. Kimberlite cleavage is conchoidal. The specific gravity of Kimberlite is 2.86-2.87. Kimberlite is translucent to opaque in nature whereas its toughness is not available. Some kimberlites contain late-stage poikilitic eastonite phlogopites.The object of the book is to provide a comprehensive survey and critique of the advances which have been made in kimberlite studies over the last twenty-five years. Kimberlites are rare rock types; however, their relative obscurity is overriden by their economic and petrological importance to a degree which is not shared with the commoner varieties of …Sep 29, 2015 · Kimberlite, and rocks with kimberlitic affinities, have a relatively wide distribution throughout the United States. They occur in the western margin of the Appalachians from New York to Tennessee; in the central region of the U.S. including Kentucky, southern Illinois, Missouri, Kansas and Arkansas, and in the Western States of Montana, Colorado, Wyoming and the Colorado Plateau. However ... Jul 26, 2023 · A new study offers clues to the mysteries of kimberlite eruptions, the source of most of the diamonds mined on Earth today. ... As bits of the keel’s carbonate- and water-rich rocks mix into the ... Around the diamond is a thin white layer you sometimes see, which indicates not a cheap glue but rather an alteration in the surrounding rock due to the ...

Rock Radio Cambodia, Phnom Penh. 8,183 likes. Rock Radio Cambodia launched in 2015. The first Cambodia radio station that focus only in ROCK music.Summer is nearly here and many of us enjoy basking in the sun at a picnic. To avoid your blanket from blowing away while you're not on it consider sewing triangular pockets on each corner to hold rocks or other weights to keep the blanket s...A rock garden is a unique way to decorate your yard and create a positive impression with visitors. Certain landscapes are more suitable for rock gardens than others. To avoid overwhelming yourself with a complicated scheme for the whole ba...The minerals in kimberlite are extremely hot at first and then cool quickly. As a result, the rocks are extremely hard and can easily hold a large amount of diamonds. Diamonds are easily extracted from yellow ground, but fresh kimberlite rock, also known as blue ground, holds the stones and must be crushed to release them. Because of the yellow ...Malachite. Malachite is an ore of Copper metal. It can be found at elevations between y=-32 and y=100. It can be found primarily in Marble or Limestone, however smaller poorer veins can also be found in Phyllite, Chalk, and Dolomite. When found in Limestone, malachite veins can also contain traces of Gypsum. Malachite Ores in Marble.Ultramafic rock. Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta -igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron ...

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Sep 15, 2023 · Crater kimberlite: Found within a volcanic crater, this type of kimberlite is a breccia or fragmented rock that contains country rock, crystals, and volcanic ash. Diatreme kimberlite: This kind creates a deep cylindrical or funnel-shaped pipe in the earth called a diatreme, and is made up of fragmented country rock and volcanic debris. 29 may 2017 ... For those who are unfamiliar, kimberlite is the ore that is mined for diamonds, and many of the early diamond mines in South Africa were located ...Rock music has had a dramatic impact on our culture since it started as old-fashioned rock ‘n’ roll in the 1950s. Transcending well beyond the music scene, it has helped shaped fashion, culture, language and art.Kimberlite, the primary host rock for diamond deposits in glaciated terrain, is a mineralogically and chemically distinct point source. A kimberlite’s variable size (50–200 m in diameter), shape (elliptical pipe or narrow, elongated dyke), competence, and degree of postglacial weathering influence the size and areal extent of dispersed ...

Arndt et al. (2010) and Cordier et al. (2015 ) suggest that olivine ‘nodules’ in kimberlites are produced by metasomatism of peridotite wall-rocks by proto-kimberlite …For decades, scientists have known that volcanic eruptions of an igneous rock known as kimberlite can contain diamonds in their rock matrix, and such kimberlite hot spots can be found in South ...Diamond-laden magmas apparently rapidly rise from deep within the Earth to the planet's surface by jettisoning weight, scientists now find. Magmas known as kimberlites have the deepest origins of ...Enhanced rock weathering is a proposed CO 2 removal strategy for mitigating climate change; its implementation can be facilitated by improving carbon verification methods. In this study, weathering experiments exposed brucite, wollastonite skarn, serpentinite, and kimberlite residues (Venetia Diamond Mine, South Africa), to wetting and drying cycles …These films might provide some New Year's inspiration, in case 2022 is looking too bleak. These days I’m perfectly content to take inspiration from wherever it comes. It’s probably an exaggeration to suggest that the human race has reached ...The kimberlite rocks contain pyrope garnets which are a bit of an oddity in Pennsylvania and, even more of an oddity - Alexandrite-effect pyropes. Containing more than 3 or 4 percent chromium, alexandrite-effect pyropes take on different colors in different light sources (The name "alexandrite" is derived from a gem variety of chrysoberyl ... Browse 130 kimberlite rock photos and images available, or start a new search to explore more photos and images. Browse Getty Images' premium collection of high-quality, authentic Kimberlite Rock stock photos, royalty-free images, and pictures. Kimberlite Rock stock photos are available in a variety of sizes and formats to fit your needs. Further, in the case of the Premier kimberlite, the isotopic composition of the ilmenite megacryst, recording the likely mantle isotopic signature, is identical within uncertainties to whole-rock samples. We conclude that the 182 W isotopic compositions of the whole-rock kimberlites most likely reflect the compositions of their mantle source(s).18 jun 2017 ... Kimberlite is a volatile-rich, potassic, ultrabasic, igneous rock which occurs as small volcanic pipes, dykes, and sills. It has a ...Group-1-kimberlite corresponds to archetypal rocks from Kimberley, South Africa that formerly were termed basaltic kimberlites. Group-2-kimberlite corresponds to micaceous or lamprophyric kimberlites. Recent studies have demonstrated that these two groups are mineralogically different and petrogenetically separate rock types. British Geological ...Looking for the perfect outdoor rocking chair to make your outdoor space more comfortable? Relax in your backyard with these top-rated rocking chairs of 2023. By clicking "TRY IT", I agree to receive newsletters and promotions from Money an...Rock Radio Cambodia, Phnom Penh. 8,183 likes. Rock Radio Cambodia launched in 2015. The first Cambodia radio station that focus only in ROCK music.

Wyoming hosts some of the best rock exposures in the world, with geologic units ranging in age from more than 3.2 billion years (3.2 Ga) in the early Precambrian (Archean) to less than 1 million (1 Ma) years in the Quaternary. These rocks derive from a wide variety of geologic environments, including sedimentary, volcanic, igneous intrusive ...

29 may 2017 ... For those who are unfamiliar, kimberlite is the ore that is mined for diamonds, and many of the early diamond mines in South Africa were located ...Diamonds are crystalline carbon and the hardest known substance. This photo shows diamonds from the Argyle Mine in northern Western Australia. Diamonds are brought to the surface from the mantle in a rare type of magma called kimberlite and erupted at a rare type of volcanic vent called a diatreme or pipe. Kimberlite is a gas-rich, potassic …Sep 25, 2019 · Figure 1 | Cross-section of kimberlite from West Greenland. Woodhead et al . 1 suggest that volcanic rocks called kimberlites originate from a reservoir that has survived deep in Earth’s mantle ... The Sloan kimberlite in Colorado was mined on a trial basis in 1994, and some 9,034 diamonds weighing a total of 342 carats were recovered from 3,300 tons of rock excavated from a 614-ft adit. The largest diamond recovered from the Sloan kimberlite was 5.14 carats and was of partial gem quality. A full-scale open pit diamond mine was operated ...Rocks are classified into three main types based on their formation process: igneous, sedimentary, and metamorphic rocks. Each type of rock has its own characteristics and is formed through different geological processes. Igneous rocks: These rocks form from the solidification of molten material called magma or lava.Ultramafic rocks are especially poor in SiO 2 and have high Mg:Fe ratios. Pyroxene (either orthopyroxene or clinopyroxene), olivine, and (less commonly) plagioclase are the dominant minerals in these rocks. The IUGS system, shown in Figure 6.117, names ultramafic rocks based on their relative amounts of olivine, orthopyroxene, and clinopyroxene.This transport mechanism is provided by some unusual volcanic rocks called kimberlite and lamproite, both of which are rocks rich in potassium and magnesium, and poor in silica. Kimberlite and lamproite are two of the deepest-sourced volcanic rocks that occur at the Earth’s surface. These volcanic rocks, that were named “kimberlite”, were to become the corner stone of the economic and industrial development of southern Africa. Following the discoveries at Kimberley, even ...Kimberlite. Our third igneous rock you can find in Tennessee is kimberlite. The mineral tends to be dark in color, depending on the magma composition that formed it in the first place. It got its name from the South African town Kimberley, where a massive 83.5-carat diamond called the “Star of South Africa” was found in 1869.

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Your rocks certainly look interesting. That being said, you are asking about one of the most difficult, complicated, and rare rock types (kimberlites). Identifying it from a couple of photographs is impossible. Kimberlites are very diverse, but generally have distinct trace mineralogy.T2 rocks are petrographically diverse, ranging from kimberlites to phonolites. T3 rocks form a cloud of points with elevated (87 Sr/ 86 Sr) 375 > 0.7041 and widely varying f(Nd, Pb); they are mostly alkaline lamprophyres. All three groups of studied rocks record a contribution from the depleted mantle, while the mantle beneath the AKP ...Kimberlites form this region do yield beautiful diamonds which mostly range from very small to a maximum of 3 carats. Customers have found 1/4 carat to 1/2 carat blue diamonds and yellow & clear diamonds between 1/4 and 2 carats within our specimens worth $1,500-$4,000. Many customers find no diamonds on the surface or within the Kimberlite.Since the growing exploration of primary diamond deposits began in 1967, >730 kimberlites and related rock types including lamproites and lamprophyres have been discovered at the southeastern side of the Yangtze Craton (Fig. 1). These mantle-derived rocks hosting diamonds are ideal targets for probing the lithosphere evolution of this craton.He’d then compare the results with the mineralogical and geochemical signatures of previously discovered kimberlite rocks originating in the region. This led to an ability to follow the indicator mineral and geochemical anomalies related to these rocks, and the gaining of a better understanding of what sample size of glacial sediments would be …Kimberlite, an igneous rock in which the majority of the world’s diamonds are found, has been reported on all major continents barring Antarctica. Yaxley et al. present mineralogical and ...The petrology of the Cleve kimberlite, Eyre peninsula, South Australia. In: Meyer,. H.O. & Leonardos, O.H. (eds) Kimberlites, Related. Rocks and Mantle ...The minerals in kimberlite are extremely hot at first and then cool quickly. As a result, the rocks are extremely hard and can easily hold a large amount of diamonds. Diamonds are easily extracted from yellow ground, but fresh kimberlite rock, also known as blue ground, holds the stones and must be crushed to release them. Because of the yellow ...Kimberlite is mainly composed of completely serpentinized subrounded olivine macrocrystals up to 1.5 cm, representing 0 to 50% of the rock (25% on average).Rare volcanic rocks known as kimberlites are produced from magmas that originate in Earth’s mantle and then erupt onto the planet’s surface. These rocks have a violent eruption style, and a...Aug 3, 2016 · This means that total kimberlite occurrences are tens of thousands of hectares of land-mass, compared to 13 billion hectares of land on the planet, of which 7% is located within Archean cratons . Given that less than 1% of kimberlites will yield an economically-viable diamond deposit, finding a viable diamond mine is a daunting task. It is most evident in kimberlites and to a lesser extent in alkali basalts, and reflects the generally high ratio of Fe 3+ to Fe 2+ in these rocks, as discussed further below. The increase in Ti is a secondary consequence of the increased tendency of Ti to partition into spinels with higher magnetite contents. ….

As bits of the keel’s carbonate- and water-rich rocks mix into the churning mantle, they could melt just enough to form an effervescent magma similar to kimberlites that would hurtle to the surface.Apr 30, 2018 · Diamonds in unweathered kimberlite, termed blue ground, must be extracted by crushing the rock and separating the diamonds. Diamonds in weathered kimberlite, called yellow ground, may be separated by panning or sluice box methods similar to gold mining. Kimberlite erodes relatively quickly from blue ground to yellow ground. At Kao (Figure 1), there are two Cretaceous-age kimberlite pipes, a larger Main Pipe of 19.8 ha and a smaller Satellite Pipe of 3.2 ha, that form part of the Lemphane – Roberts belt of kimberlites in the Maluti Mountains of northern Lesotho that intruded the ca. 180 million year (Ma), Jurassic-age Lesotho Formation (Drakensberg) basalts some ...Kimberlite is a type of igneous rock that is ultramafic and ultrapotassic. Its mineral content usually includes olivine, phlogopite, pyroxene, and garnet, accompanied by a variety of trace minerals.Kimberlite occurs in the Earth's crust in vertical structures known as kimberlite pipes.These pipes are the most important source of mined diamonds today. In addition, the scientific study of ...An almost ubiquitous feature of kimberlite rocks is their high volatile content compared to most other silicate rock types. Abundances measured in rocks often range as high as 15 wt.% for CO 2 and 12 wt.% for water. This generally implies a high volatile content for kimberlite magmas, although the exact origins of this water and to a lesser …hand specimen of kimberlite-looking rock in the S.A. Mines Department collection. The o utcrops were described in a short paper by Tucker and Collerson (1972) which gives g eneral knowledge ofRed Hills. The Red Hills region in Kansas is another awesome location for rockhounding. Here, you can find gypsum, all three varieties! Namely, the selenite, flat, transparent, or diamond-shaped crystals variant, the satin spar, and the rock gypsum. You can also find anhydrite and dolomite in the Red Hills area.Research highlights A temporal and spatial relationship between small-volume magmas like kimberlites and relatively much larger volume continental flood basalts exists in several Large Igneous Provinces of the world. Geographical zonation of end-Cretaceous kimberlite, carbonatite, lamprophyre and other alkaline rock spectrum in the Deccan Large Igneous Province is related to interaction ...Kimberlite Rocks offers a unique treasure hunting adventure where you can find real treasures and keep them for yourself. Kimberlite Rocks is a celestial paradise filled with … Kimberlite rocks, Browse 130 kimberlite rock photos and images available, or start a new search to explore more photos and images. Browse Getty Images' premium collection of high-quality, authentic Kimberlite Rock stock photos, royalty-free images, and pictures. Kimberlite Rock stock photos are available in a variety of sizes and formats to fit your needs., Kimberlite, as originally described by Lewis (1887, see Dawson, 1980) was a serpentinized, ultrabasic, phlogopite-bearing, diamondiferous volcanic breccia found at the Kimberley diamond mine, S Africa.The term blue ground refers to unoxidized slate-blue or blue-green kimberlite that occurs below the superficial oxidized zone. Since its original description, "kimberlite" has been extended ..., The meaning of Kimberlite is stability. Kimberlite was called Diamond Rock in earlier times due to the presence of Diamonds. The presence of other crystals in it also earned names like Peridotite Diamond and Olivinite Diamond. Today, this Diamond-Bearing Rock is used for clarity, vitality, grounding, karmic healing, and transformation., Abstract. The petrography of kimberlite indicates that it is a hybrid rock consisting of fragments of rocks of upper mantle and deep crustal origin intermixed with the …, The DO-18 kimberlite is a Group I kimberlite that is part of the Tli Kwi Cho kimberlite complex in the Lac de Gras kimberlite field of the Archaean Slave Craton in northern Canada (Supplementary ..., kimberlite eruption, small but powerful volcanic eruption caused by the rapid ascent of kimberlites—a type of intrusive igneous rock originating in the asthenosphere—through the lithosphere and onto the surface of the Earth.Kimberlites are thought to rise through a series of fissures in the rock.They form vertical pipelike structures that penetrate the surrounding rock., Petrogenesis of the diamondiferous Pipe-8 ultramafic intrusion from the Wajrakarur kimberlite field of Southern India and its relation to the worldwide Mesoproterozoic (~1.1 Ga) magmatism of kimberlite and related rocks. Geoscience Frontiers, Vol. 11, Issue. 3, p. 793., In the case of kimberlite, pipes of igneous rock are formed. Other 'foreign' nodules of crystalline rocks and minerals were also brought up to the crust ..., Xenolith. Gabbroic xenolith in granite in Rock Creek Canyon, eastern Sierra Nevada, California. A xenolith ("foreign rock") is a rock fragment ( country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term xenolith is almost exclusively used to describe inclusions in igneous rock ..., To solve the mystery, the international team analysed historical data on continental plates, the vast, slow-moving slabs of Earth’s crust, and kimberlites, the diamond-bearing rocks ejected by ..., Carbon capture and storage has a fundamental role in limiting anthropogenic warming to 1.5–2 °C. This Review discusses the basis, potential and limitations of in situ mineral carbonation as a ..., To reach diamonds at the bottom of kimberlite pipes rocks are blasted and pit-mining begins. Pit-mining is the most common way to recover diamonds. In pit mining, heavy machinery, hydraulic ..., Many features of these rocks are atypical of kimberlite and indicate a complex intrusion history. The magmatic rocks contain two generations of relatively abundant olivine in a fine-grained matrix composed of phlogopite, clinopyroxene, amphibole, perovskite, spinel, serpentine and glass. Although some petrographic features of these …, The meaning of Kimberlite is stability. Kimberlite was called Diamond Rock in earlier times due to the presence of Diamonds. The presence of other crystals in it also earned names like Peridotite Diamond and Olivinite Diamond. Today, this Diamond-Bearing Rock is used for clarity, vitality, grounding, karmic healing, and transformation., (a) Large olivine nodules in the Marsfontein orangeite in the Northern Province of South Africa (photo reproduced with permission of James Campbell, Managing Director of Botswana Diamonds plc); (b) centimetric ellipsoidal olivine nodules in a kimberlite from Igwisi Hills, Tanzania (from Russell et al., 2019); (c) photo of the same nodules taken …, The kimberlite rock was named after Kimberley, a place in South Africa. The first place identifying kimberlite. Previously, Kimberly diamonds were contained in weathered kimberlite that had been tinted yellow by limonite and was known as yellow ground. More extensive workings produced less altered rock, serpentinized kimberlite, …, Lamproite. Lamproite is an ultrapotassic mantle -derived volcanic or subvolcanic rock. It has low CaO, Al 2 O 3, Na 2 O, high K 2 O/Al 2 O 3, a relatively high MgO content and extreme enrichment in incompatible elements . Lamproites are geographically widespread yet are volumetrically insignificant. Unlike kimberlites, which are found ..., Interstitial and replacement carbonates yield intermediate results. Kimberlite whole rocks were leached with 2N HCl to remove the carbonate fraction which on analysis, yields Sr 87 /Sr 86 ratios between 0.7051 and 0.7075. The Sr contents of the whole rocks before leaching range from 660 ppm to 1481 ppm; these are minima for the carbonate ..., Potassic igneous rocks were originally recognized in the late 19th century by Iddings (), who described some orthoclase-bearing basalts from the Yellowstone Park, Wyoming, and coined the term “shoshonite”.In the last century, petrologists generated many names for potassic igneous rocks which were either based on their mineralogy or, more …, Kimberlite is an igneous rock that major source of diamonds. Kimberlite is a variety of peridotite . It is rich in mica minerals content and often in form of crystals of phlogopite. Other containt abundant minerals are chrome-diopside, olivine, and chromium- and pyrope-rich garnet ., The kimberlite volcanic rocks are assigned to the sedimentary strata in which they are intercalated, e.g., Cantuar-equivalent kimberlite, when this is known. The kimberlite samples investigated in this study were collected from drillcore, excepting the Sturgeon Lake samples that are from an ice-rafted megalith “outcrop.”, It seems, therefore, that diamonds must emerge from the bowels of the earth with the eruption of volcanic rocks. Diamonds are carried by eruptive rocks, pipes and dykes that contain kimberlite or lamproitic rocks. Pipes, as miners call them, are 100 million to 1.2 billion years old; these violent eruptions of volcanic rocks could not happen today., kimberlite, also called blue ground, a dark-coloured, heavy, often altered and brecciated (fragmented), intrusive igneous rockthat contains diamondsin its rockmatrix. It has a …, Abstract. One of the few windows through the earth’s relatively thin crust into its underlying mantle is the diatreme or pipe that occasionally has pierced the crust to bring mantle material such as diamond to the surface (Fig. 9–1). Experimental work has shown that most synthetic diamonds generally must have very high temperatures (2,000 ..., Kimberlite is an igneous rock that major source of diamonds. Kimberlite is a variety of peridotite . It is rich in mica …, KImberlite.cambodia, Phnom Penh. 613 likes. Beauty / Healthy / Quality Contact number :096 33 03 666 096 3, Kimberlite, an igneous rock in which the majority of the world’s diamonds are found, has been reported on all major continents barring Antarctica. Yaxley et al. present mineralogical and ..., Kimberlite rock samples are a mainstay of diamond exploration. Formed millions of years ago at depths of 150 to 400 kilometres, kimberlites are brought to the surface by geological and chemical forces. Sometimes, the igneous rocks carry diamonds embedded within them. “For researchers, kimberlites are subterranean rockets that pick …, Kimberlite with diamond: Kimberlite, the rock that is found in many diamond pipes, is a variety of peridotite. The specimen above is a piece of kimberlite with numerous visible grains of phlogopite and a six millimeter octahedral diamond crystal of about 1.8 carats. This specimen is from the Finsch Diamond Mine in South Africa., Research highlights A temporal and spatial relationship between small-volume magmas like kimberlites and relatively much larger volume continental flood basalts exists in several Large Igneous Provinces of the world. Geographical zonation of end-Cretaceous kimberlite, carbonatite, lamprophyre and other alkaline rock spectrum in the Deccan Large Igneous Province is related to interaction ..., Dec 6, 2022 · The minerals in kimberlite are extremely hot at first and then cool quickly. As a result, the rocks are extremely hard and can easily hold a large amount of diamonds. Diamonds are easily extracted from yellow ground, but fresh kimberlite rock, also known as blue ground, holds the stones and must be crushed to release them. Because of the yellow ... , Kimberlites, small-volume volcanic rocks that are the source of most diamonds, ... International Kimberlite Conference: Extended Abstracts 8, ..., Kimberlite is an igneous rock that major source of diamonds. Kimberlite is a variety of peridotite . It is rich in mica minerals content and often in form of crystals of phlogopite. Other containt abundant minerals are chrome-diopside, olivine, and chromium- and pyrope-rich garnet .