Image Orthopyroxenite ALH84001 .gif right thumb A sample of the orthopyroxenite meteorite ALH84001 Pyroxenite is an ultramafic igneous Rock geology rock consisting essentially of mineral s of the pyroxene group, such as augite and diopside , hypersthene , bronzite or enstatite . They are classified see diagram below into clinopyroxenites, orthopyroxenites, and the websterites which contain both pyroxenes. Closely allied to this group are the hornblendite s, consisting essentially of hornblende and other amphibole s. They are essentially of Igneous rock igneous origin, though some pyroxenites are included in the Metamorphism metamorphic Lewisian complex of Scotland . The pyroxene rich rocks which result from the contact metamorphism of impure limestone s are described as pyroxene hornfels es calc silicate hornfelses . Intrusive and mantle pyroxenites The igneous pyroxenites are closely allied to the gabbro s and norite s, from which they differ by the absence of feldspar , and to the peridotite s, which are distinguished from them by containing more than 40 olivine . This connection is indicated also by their mode of occurrence, for they usually accompany masses of gabbro and peridotite and seldom are found by themselves. They are often very coarse grained, containing individual crystal s which may be several inches in length. The principal accessory minerals, in addition to olivine ..., they are not eclogite s, as clinopyroxene in them is less sodic than omphacite and the pyroxenite compositions typically are unlike that of basalt . It has been proposed that large volumes of pyroxenite ... melting of eclogite, and that such pyroxenite volumes are important sources of basalt magma e.g., Sobolev and others, 2007 . Pyroxenite lavas Purely pyroxene bearing volcanic rocks are rare, restricted ... belt s. Here, the pyroxenite lavas are created by in situ crystallisation and accumulation of pyroxene ... . Image PeridOlPx.jpg thumb right Classification diagram for peridotite and pyroxenite, based ... more details
Orphan date December 2010 Pyroxenite Promontory is a promontory rising to about 1,150 m near the west end of Dufek Massif in the Pensacola Mountains . The feature is located west of Neuburg Peak and projects northwest toward Rautio Nunatak . The name was proposed by Arthur B. Ford , leader of the United States Geological Survey USGS geological party in the Pensacola Mountains, 1978 79, from the pyroxenite rock which forms a conspicuous dark layer along the cliffs of the promontory. usgs gazetteer coord 82 37 S 53 0 W display title Category Promontories of Antarctica Category Landforms of Edith Ronne Land FilchnerRonne geo stub ... more details
Image Etang de lers lherzolite.jpg thumb right 250px Lherzolite at Etang de Lers, Ari ge, France Image Lherzolite eifel.jpg thumb right 250px Lherzolite xenolith from Eifel , Germany Lherzolite is a type of ultramafic igneous rock . It is a coarse grained rock consisting of 40 to 90 olivine along with significant orthopyroxene and lesser calcic chromium rich clinopyroxene . Minor minerals include chromium and aluminium spinel s and garnet s. Plagioclase can occur in lherzolites and other peridotite s that crystallize at relatively shallow depths 20 30 km . At greater depth plagioclase is unstable and is replaced by spinel. At approximately 90 km depth, pyrope garnet becomes the stable aluminous phase. Garnet lherzolite is a major constituent of the Earth s upper mantle extending to 300 km depth . Lherzolite is known from the lower ultramafic part of ophiolite complexes although harzburgite is more common in this setting , from alpine type peridotite massifs, from fracture zones adjacent to mid oceanic ridges, and as xenolith s in kimberlite pipes and alkali basalts. Partial melting of spinel lherzolite is one of the primary sources of basalt ic magma . The name is derived from the Lherz Massif , an alpine peridotite complex also known as orogenic lherzolite complex , the type locality at Etang de Lers, near Massat in the France French Pyrenees Lherz is the archaic spelling of this location. The Lherz massif also contains harzburgite and dunite , as well as layers of spinel pyroxenite , garnet pyroxenite, and hornblendite . The layers represent partial melts extracted from the host peridotite during decompression in the Mantle geology mantle long before emplacement into the crust. The Lherz massif is unique because it has been emplaced into Paleozoic carbonates limestone s and dolostone s , which form mixed breccia s of limestone lherzolite around the margins of the massif. References Blatt, Harvey and Robert J. Tracy, 1996, Petrology Igneous, Sediment ... more details
The Lac des les igneous complex of northwestern Ontario , Canada is a layered intrusion layered gabbroic intrusion which is the host for the largest palladium orebody in Canada. ref name Infomine http www.infomine.com minesite minesite.asp?site lacdesiles Infomine report on Lac des les ref The orebody is currently being mined as a combined open pit and underground operation by North American Palladium . ref name Infomine The complex is located in the Canadian Shield some 85 kilometers northwest of Thunder Bay , Ontario and Lake Superior at 49.10.00 N 089.36.00 W. ref name GSC http www4.geology.utoronto.ca faculty mungall Website igcp479namerica dp512.html Geological Survey of Canada, World Minerals Geoscience Database Project, Entry 512 ref The complex includes gabbro , pyroxenite , Norite gabbronorite and websterite intrusive into granitic gneiss country rock. The ore minerals occur within gabbroic pegmatite s and gabbro breccia zones. The Archean complex has been dated at 2738 27 Ma by Samarium neodymium dating Sm Nd dating on pyroxenite. ref name GSC The Roby Zone orebody of the complex is a platinum group elements PGE deposit with associated gold, copper and nickel mineralization. Ore mineralogy includes pyrrhotite , pentlandite , chalcopyrite , pyrite and the rare PGE minerals vysotskite Pd,Ni S, braggite Pt,Pd,Ni S, kotulskite Pd Te,Bi sub 1 2 sub , isomertieite Pd sub 11 sub Sb sub 2 sub As sub 2 sub , merenskyite Pd,Pt Te,Bi sub 2 sub , sperrylite PtAs sub 2 sub and moncheite Pt,Pd Te,Bi sub 2 sub . ref name GSC ref http www.mindat.org loc 43996.html Mindat ref See also Portal Volcanism of Canada Volcanism of Canada Volcanism of Eastern Canada References Reflist coord missing Ontario DEFAULTSORT Lac Des Iles Igneous Complex Category Volcanism of Ontario Category Economic geology Category Palladium Category Archean volcanism Category Layered intrusions Canada geology stub NorthernOntario geo stub ... more details
, norite and feldspar pyroxenite s. Thickness up to 700 feet 210 m . The ultramafic zone is composed ... pyroxenite . The upper third is massive bronzite pyroxenite. The ultramafic zone averages around ... more details
For the igneous rock type websterite , see pyroxenite . Aluminite is a hydrous aluminium sulfate mineral with formula Al sub 2 sub SO sub 4 sub OH sub 4 sub 7 H sub 2 sub O . It is an earthy white to gray white monoclinic mineral which almost never exhibits crystal form. It forms botryoidal to mammillary clay like masses. It is very soft Mohs hardness of 1 with a specific gravity of 1.66 1.7. It forms as an oxidation product of pyrite and marcasite along with aluminous silicates and clays. It was first described in 1807 from Halle, Saxony Anhalt, Germany . It is also known as alley stone and websterite named after English geologist Thomas Webster geologist Thomas Webster . Aluminite is used by tile & masonry workers to reduce the setting time of cementitious mortars. References http www.mindat.org min 154.html Mindat w locations http webmineral.com data Aluminite.shtml Webmineral Category Aluminium minerals Category Sulfate minerals Category Monoclinic minerals sulfate mineral stub ca Aluminita de Aluminit es Aluminita fa hr Aluminit it Alluminite nl Aluminiet pt Aluminita sr sh Aluminit uk ... more details
Unreferenced date December 2009 Dablink This article is about the geology of the European Alps . For the main article see geology of the Alps Geology of the Alps The Ivrea zone is a tectonics tectonic terrane in the Italy Italian Alps , that consists of a steeply Strike and dip dipping piece of the Earth s lower crust geology crust of the Apulian plate . The zone is named after the Italian city of Ivrea . Geologically the Ivrea zone is considered a part of the Southern Alps geology Southern Alps . Most rocks in the zone are sedimentary rock sedimentary , for example limestone s that have been turned into marble by metamorphism . Most of the zone has been through granulite facies metamorphism and was intruded by mafic Intrusion pluton s. This is the type of rock common in the lower regions of the crust. When the terrane was Tectonic uplift uplifted during the formation of the Alps, the upper crust was eroded off so that these rocks are now at the surface. Geophysics Geophysical research shows the Mantle geology mantle is relatively close under the surface at the Ivrea zone. Some geologists think the boundary between pyroxenite s and lherzolite s, that is also found in outcrop s in the Ivrea zone, represents the Mohorovi i discontinuity the Moho . The Moho is Seismology seismologically defined as the boundary between the crust and mantle. See also Mohorovi i discontinuity DEFAULTSORT Ivrea Zone Category Structural geology Category Geology of the Alps Category Terranes it Zona Ivrea Verbano nl Ivrea zone ... more details
Cafetite is a rare titanium oxide mineral with formula calcium Ca , magnesium Mg iron Fe , aluminium Al sub 2 sub titanium Ti sub 4 sub oxygen O sub 12 sub 4 hydrogen H sub 2 sub O . It was first described in 1959 for an occurrence in the Afrikanda Massif , Afrikanda rural locality Afrikanda , Kola Peninsula , Murmanskaja Oblast , Northern Region, Russia . ref name Mindat http www.mindat.org min 850.html Mindat.org ref ref name HDM http rruff.geo.arizona.edu doclib hom cafetite.pdf Handbook of Mineralogy ref It is also reported from the Khibiny Massif Khibiny and Kovdor Massif Kovdor massif s of the Kola Peninsula and from Meagher County, Montana , USA. ref name Mindat It occurs in pegmatite s in a pyroxenite intrusion as crystals in Miarolitic cavity miarolitic cavities . It occurs associated with ilmenite , titaniferous magnetite , titanite , anatase , perovskite , baddeleyite , phlogopite , Chlorite group clinochlore and kassite . ref name HDM References Reflist http www.webmineral.com data Cafetite.shtml Webmineral data oxide mineral stub Category Oxide minerals Category Titanium minerals it Cafetite ... more details
about the mineral the ancient people Kassites Infobox mineral name Kassite category Hydroxide mineral boxwidth boxbgcolor image caption formula CaTi sub 2 sub O sub 4 sub OH sub 2 sub molweight 235.09 strunz 04.DH.10 dana color Brown red, colorless, light yellow habit Pseudo hexagonal system Monoclinic Prismatic 2 m , space group P2 sub 1 sub a lattice twinning cleavage 010 Perfect fracture Brittle tenacity mohs 5 luster Adamantine refractive n sub sub 1.95, n sub sub 2.13, n sub sub 2.21 opticalprop Biaxial , 2V 58 , Dispersion very strong, r v birefringence 0.26 pleochroism none streak White gravity 3.42 density melt fusibility diagnostic solubility diaphaneity other Not radioactive references ref name Webmin http webmineral.com data Kassite.shtml Kassite at Webmineral ref ref name Mindat http www.mindat.org min 2166.html Kassite at Mindat ref Kassite is a rare mineral with formula CaTi sub 2 sub O sub 4 sub OH sub 2 sub . It crystallizes in the orthorhombic crystal system and forms radiating rosettes and pseudo hexagonal tabular crystals which are commonly Crystal twinning twinned . Crystals are brownish pink to pale yellow and are translucent with an adamantine luster. Cleavage is distinct and the crystals are very brittle. It was first described in 1965 from the Afrikanda pyroxenite massif , Kola Peninsula , Russia and was named for Nikolai Grigorievich Kassin 1885 1949 , Russian geologist. It occurs as miarolitic miarolytic cavity fillings of alkalic pegmatite s in the Kola occurrence and in nepheline syenite in the Magnet Cove igneous complex of Arkansas , USA. Its mineral association includes cafetite , perovskite , titanite , rutile and ilmenite . It is polymorphous with cafetite. References reflist Category Oxide minerals oxide mineral stub it Kassite ... more details
Infobox mountain name Mont Yamaska photo MT YAMASKA.jpg photo caption Aerial Shot of Mount Yamaska elevation m 411 elevation ref prominence location Saint Paul d Abbotsford, Quebec Saint Paul d Abbotsford , 12 kilometers northwest of Granby, Quebec , Canada range Monteregian Hills coordinates coord 45 27 25 N 72 52 19 W type mountain region CA display inline,title topo National Topographic System NTS 031H 07 type Intrusive stock geology stock age Early Cretaceous volcanic arc belt last eruption first ascent easiest route Mont Yamaska is part of the Monteregian Hills in southern Quebec. Its summit stands Convert 411 m ft 0 abbr on above sea level. This mountain is largely covered with deciduous forest dominated by sugar maple . Some apple orchards are raised on lower slopes. Geology Mont Yamaska is composed of igneous rock and hornfels . The igneous rock is mostly mafic with much gabbro , essexite , and a titanium rich pyroxenite . Mont Yamaska might be the deep extension of a vastly eroded ancient volcanic complex, which was probably active about 125 million years ago. ref name SI http www.oceanexplorer.noaa.gov explorations 05stepstones background geologic history geologic history.html A Hundred Million Year History of the Corner Rise and New England Seamounts Retrieved on 2007 08 01 ref The mountain was created when the North American Plate moved westward over the New England hotspot , ref name SI along with the other mountains of the Monteregian Hills that form part of the Great Meteor hotspot track . See also Yamaska National Park References reflist External links Sister project links http montyamaska.nature action.qc.ca Le mont Yamaska sous mon aile http www.montyamaska.org Fondation pour la conservation du mont Yamaska DEFAULTSORT Yamaska Category Geography of Mont r gie Category Mountains of Quebec Category Volcanism of Quebec Category Stocks geology Category Mountains under 1000 metres Quebec geo stub fr Mont Yamaska nl Mont Yamaska ... more details
Unreferenced date July 2007 Image Flow banded rhyolite.JPG thumb 300px Flow banded w Rhyolite rhyolite in the Dunn Point Formation w Ordovician Ordovician exposed near Arisaig, Nova Scotia. Image Peroxenite banding.JPG thumb 260px Flow banding at the rim of a peridotite intrusion . Dark and green pyroxenite bands at the bottom represent the melt, brownish lherzolite bands at the top the solid phase. Near Midsund , Norway , 1 euro coins 1 euro coin for scale. Flow banding is a geological term to describe bands or layers that can sometimes be seen in rock that formed from the substance magma molten rock or magma. Flow banding is caused by friction of the viscous magma which is in contact with a solid rock interface, usually the wall rock to an intrusive chamber or if the magma is erupted, the surface of the earth across which a lava is flowing. The friction and viscosity of the magma causes phenocrysts and xenolith s within the magma or lava to slow down near the interface and become trapped in a viscous layer. This forms laminar flow, which manifests as a banded, streaky appearance. Flow banding is the result of a process of Fractional crystallization geology fractional crystallization which occurs by convection , if the crystals which are caught in the flow banded margins are removed from the melt. This can change the composition of the melt in large intrusions, leading to differentiation. In layered intrusion s flow banding can occur with crystal cumulate rock accumulation , forming pseudo sedimentary structures. Flow banding can also occur due to disturbances in the field of flow thus forming a haemotomtic flow band, these are common in the region of upper Iceland, there are many good Icelandic videos in which this rare phenomenon can be observed. See also Cumulate rock Igneous differentiation Fractional crystallization Category Igneous rocks Category Structural geology Category Volcanology Category Igneous petrology Volcanology stub he ... more details
Infobox mountain name Kosvinsky Kamen other name photo photo caption elevation m 1519 elevation ref prominence listing location Russia range Ural Mountains coordinates coord 59 31 N 59 03 E type mountain display inline,title topo first ascent easiest route Mount Kosvinsky Kamen , Kosvinsky Mountain , Kosvinsky Rock or Rostesnoy Rock lang ru , , is a mountain in the northern Urals , Sverdlovsk Oblast , Russia . ref Brockhaus and Efron describe its location within the Russian Empire as Verkhoturye uyezd , Perm Governorate , in the okrug of the Bogoslovsky copper plant ref ref name efron http www.vehi.net brokgauz all 055 55031.shtml , Brockhaus and Efron Encyclopedic Dictionary ru icon ref Its head is bare of vegetation with uneven rocky surface with small lakes fed by snow melting. The Kosva River flows from the mountain, hence the name. ref name efron The Great Soviet Encyclopedia describes Kosvinsky Rock as mountain massif of height 1,519 m. ref Brockhaus and Efron say that its elevation is 2,375 ft., mountain foot circumference is about 40 km. ref Its constitution is pyroxenite s and dunite s of lower and middle Paleozoic era . The slopes are covered with conifer s with some birch up to 900 1000 m, with alpine tundra above. ref , Great Soviet Encyclopedia ru icon ref Military According to a 1997 article in the Washington Times , a CIA report stated that there were construction works for a nuclear survivable, strategic command post at Kosvinsky Mountain . ref http www.globalsecurity.org wmd library news russia 1997 bmd970404a.htm Moscow builds bunkers against nuclear attack , by Bill Gertz , Washington Times , April 1, 1997 ref References and notes reflist Category Mountains of Russia Category Sverdlovsk Oblast SverdlovskOblast geo stub ru ... more details
dablink This article is about an island part of Egypt . For other islands called Saint John s Island, see St. John s Island . File Forsterite 223825.jpg thumb Historic specimen of Forsterite var. peridot , 1.3 x 0.7 x 0.4 cm. This ancient locality was mined for peridot as early as 1300 BC. St. John s Island also known as Zabargad, Zebirget, Topazios is the largest of a group of islands in Foul Bay , Red Sea in Southern Egypt . It covers an area of 4.50 square kilometres approx. . It is not a quaternary volcano volcanic island, but rather is believed to be an upthrusted part of upper mantle material. The nearest island is Rocky Island Egypt Rocky Island . The island is slightly north of the Tropic of Cancer , and its highest point is 235 metres. Geology The island is considered geology geologically unique as it is uplifted Mantle geology mantle , a fragment of the sub Red Sea lithosphere . Rocks on the island are mainly lower Crust geology crust al metamorphic rock s. The island became present above sea level after Africa n and Asia tic continental plates converged to cause rocks in the lower crust to be uplifted. The island comprises three massives of peridotite , which are rich in the gemstone peridote olivine . This gem makes the island notable as it is believed to be the first discovered source of peridot , which was called topazios in ancient times, hence the Greece Greek name for the island, Topazios . Layers of spinel lherzolites with anhydrous Al diopside pyroxenite s and hydrous Cr diopside pyroxenite s can be found too on the island. The presence of all of these minerals has led to mining on the island which dates back as early as ancient times. Nature The island is part of the Elba National Park meaning the island is conserved. However, the island was closed to the public for one year due to damage to corals and the disturbance of birds who breed on the island. Birds The island serves as a breeding ground for at least 9 known species of birds. The most rec ... more details
Infobox mountain name Mont Rougemont photo Le Mont Rougemont.jpg photo caption elevation m 390 elevation ref prominence location Rougemont, Quebec Rougemont , 18 kilometres southwest of Saint Hyacinthe , Quebec , Canada range Monteregian Hills coordinates coord 45 28 36 N 73 03 17 W type mountain region CA topo National Topographic System NTS 031H 06 type Intrusive stock geology stock age Early Cretaceous volcanic arc belt last eruption first ascent easiest route Mont Rougemont is part of the Monteregian Hills in southern Quebec . It is composed of igneous rock and hornfels . The summit stands convert 366 m ft 0 abbr on above sea level. The mountain is mostly covered with sugar maple dominated forest . Apple orchards and vineyards are cultivated on many of the lower slopes, and much of the fruit is used to make cider . Geology The igneous material is composed almost entirely of mafic and ultramafic rock such as gabbro and olivine bearing pyroxenite . Mont Rougemont might be the deep extension of a vastly eroded ancient volcanic complex, which was probably active about 125 million years ago. ref name SI http www.oceanexplorer.noaa.gov explorations 05stepstones background geologic history geologic history.html A Hundred Million Year History of the Corner Rise and New England Seamounts Retrieved on 2007 08 01 ref The mountain was created when the North American Plate moved westward over the New England hotspot , ref name SI along with the other mountains of the Monteregian Hills . It forms part of the vast Great Meteor hotspot track . External links fr icon http www.apddmr.ca Ass. pour la protection et le d veloppement durable du mont Rougemont APDDMR fr icon http www.nature action.qc.ca rouge plan.html Nature Action Quebec fr icon http www.ouellette001.com Quebec en photos 16 Monteregie Rouville Rougemont 001.htm Quebec in photographs Mont r gie References reflist DEFAULTSORT Rougemont Category Geography of Mont r gie Category Mountains of Quebec Category Volcanism of ... more details
A QAPF diagram is a double triangle diagram which is used to classify igneous rock s based on mineralogy mineralogic composition. The acronym , QAPF, stands for Quartz , feldspar Alkali feldspar , Plagioclase , Feldspathoid Foid . These are the mineral groups used for classification in QAPF diagram. Q, A, P and F percentages are normalized recalculated so that their sum is 100 . Origin QAPF diagrams were created by the International Union of Geological Sciences IUGS Subcommission on the Systematics of Igneous Rocks . The diagrams are accepted by geologists worldwide as a classification of igneous, especially plutonic rocks. Usage QAPF diagrams are mostly used to classify Intrusion plutonic rocks phaneritic rocks Figure 1 , but are also used to classify volcanic rock s Figure 2 if modal mineralogical compositions have been determined. QAPF diagrams are not used to classify pyroclastic rock s or volcanic rocks if modal mineralogical composition is not determined, instead the TAS classification Total Alkali Silica is used. TAS is also used if volcanic rock contains volcanic glass such as obsidian . QAPF diagrams are also not used if mafic mineral s make up more than 90 of the rock composition for example peridotite s and pyroxenite s . An exact name can be given only if the mineralogical composition is known, which cannot be determined in the field. Therefore, provisional or field classifications Figures 3 and 4 are used, which are simplified versions of Figures 1 and 2. gallery caption QAPF diagram gallery widths 220px heights 250px perrow 2 Image QAPF diagram plutonic.gif Figure 1. This classification is used if rock sample has phaneritic texture plutonic rocks . Image QAPF diagram volcanic.gif Figure 2. This classification is used if rock sample has fine grained texture volcanic rocks but modal mineralogical composition can be determined. Image QAPF diagram plutonic field.gif Figure 3. This is provisional classification for phaneritic igneous rocks field classificat ... more details
File Muskox intrusion and groups.png thumb right 250px Geologic map of the Muskox intrusion and adjacent geologic groups The Muskox intrusion is a layered intrusion in Nunavut , Canada . It is located Convert 144 km mi abbr on northeast of Great Bear Lake and Convert 90 km mi abbr on south of Kugluktuk, Nunavut Kugluktuk on Coronation Gulf . It was formed during a large magmatic event during the Proterozoic by hotspot geology hotspot or mantle plume volcanism that emplaced the widespread Coppermine River Group flood basalt s. The intrusion is a tilted trough shaped body with an exposed length of Convert 120 km mi abbr on and a thickness or origiinal vertical dimension of over Convert 6 km mi abbr on . Rock types include picrite , peridotite , dunite , pyroxenite , gabbro and granophyre . A feeder Dike geology dike of olivine gabbro is exposed below the now tilted sequence. ref Alexander R. McBirney, Igneous Petrology , Jones & Bartlett, 2006, 3rd ed., pp. 224 226 ISBN 0763734489 ref Potassium argon dating in the region provides an age of 1095 1155 Ma for the Muskox intrusion, 1100 1200 Ma for the Mackenzie dike swarm and 740 1200 Ma for the Coppermine basalt flows younger dates are interpreted as having been reset by later intrusion of gabbro sills at 604 718 Ma . Further stratigraphic and structural evidence provides further support that the Muskox, the MacKenzie dikes and the Coppermine flows are of the same magmatic event that formed the Mackenzie Large Igneous Province and the Muskox is interpreted as occupying the magma chamber which fed the volcanism. ref Gunter Faure, Origin of Igneous Rocks , Springer, 1st ed., 2000, pp. 357 358, ISBN 3540677720 ref See also Portal Volcanism of Canada Volcanism of Canada Volcanism of Northern Canada Mackenzie hotspot References Reflist http www.cosis.net abstracts EAE03 06848 EAE03 J 06848.pdf Re Os isotopic study of the Muskox intrusion, NWT, Canada coord 67 12 30 N 114 53 00 W display title Category Volcanism of Nunavut Ca ... more details
Ultramafic Sequence of dunite s, harzburgite s, olivine bronzitite s and pyroxenite s together ... pyroxenite bronzitite and websterite units are economic concentrations of nickel , copper , cobalt ... more details
File Diamant Excelsior Croquis Streeter s Precious Stones 1899.jpg thumb The convert 972 carat g Excelsior diamond , the largest found at the Jagersfontein Mine. Jagersfontein Mine IPAc en icon j e r z f n t e n is an abandoned open pit mine in South Africa located close to the town of Jagersfontein and approximately Convert 68 mi south west of Bloemfontein . ref name distance http www.mindat.org loc 3076.html Jagersfontein Mine, Jagersfontein, Free State Province, South Africa , Mindat.org ref ref name places http www.places.co.za html jagersfontein.html Jagersfontein , Places.co.za ref Since it was first established in 1888, ref name britannica http www.britannica.com ebc article 9043237 Jagersfontein entry , Encyclop dia Britannica ref ref name showcaves http www.showcaves.com english za mines Jagersfontein.html Jagersfontein Mine , Showcaves.com ref two of the ten biggest diamonds ever discovered, the Excelsior Diamond Excelsior and the Reitz now called the Jubilee Diamond Jubilee , were mined from Jagersfontein. ref name places The term Jagers has since been coined to denote the distinctive faint bluish tint of the gems from this mine. ref name excelsior http famousdiamonds.tripod.com excelsiordiamond.html The Excelsior Diamond , Famous, Historic and Notable Diamonds, Tripod.com ref Among geologists, Jagersfontein is known as a kimberlite pipe , ref name kimberlite http www.dtm.ciw.edu kaapvaal images field jagersfontein.html Photograph showing the circular geometry of the Jagersfontein kimberlite , Department of Terrestrial Magnetism, Carnegie Institution of Washington br http www.minersoc.org pages Archive MM Volume 40 40 309 6.htm Stressed Pyroxenite Nodules from the Jagersfontein Kimberlite , G. D. Borley and P. Suddaby, Mineralogical Magazine March 1975 v. 40 no. 309 p. 6 12 doi 10.1180 minmag.1975.040.309.02 br http www.cosis.net abstracts 9IKC 00360 9IKC A 00360 1.pdf Iron carbide and metallic inclusions in diamonds from Jagersfontein , A. P. ... more details
taxobox image Ceanothus ophiochilus 2.jpg status LT status system ESA regnum Plant ae unranked divisio Angiosperms unranked classis Eudicots unranked ordo Rosids ordo Rosales familia Rhamnaceae genus Ceanothus species C. ophiochilus binomial Ceanothus ophiochilus binomial authority Boyd, Ross & Arnseth Ceanothus ophiochilus is a rare species of flowering shrub known by the common name Vail Lake ceanothus , native to Southern California . It was not described until 1991. Distribution The Ceanothus ophiochilus plant is Endemism endemic to California , where it is only known from a few sites in the vicinity of Vail Lake west of the Santa Rosa Mountains California Santa Rosa Mountains in southwestern Riverside County, California Riverside County . ref name cnps http www.rareplants.cnps.org detail 1615.html Ceanothus ophiochilus . California Native Plant Society CNPS . 2010. Inventory of Rare and Endangered Plants online edition, v7 10d . Accessed January 29, 2011. ref This is a plant of the chaparral plant community , and in its small native range which currently is only a few acres, it grows in pyroxenite soil atop an ancient volcano . Its elevation range is convert 580 1065 m ft . ref name cnps One of the three remaining populations of this plant is on private property that may face development in the future. It was listed as a threatened species on the federal level in 1998, and an endangered species by the state of California in 1994. ref name cnps There are up to 9000 individuals remaining, but some of these are Hybrid biology hybrids with Ceanothus crassifolius . ref name tnc http www.natureserve.org explorer servlet NatureServe?searchName Ceanothus ophiochilus The Nature Conservancy ref Description Ceanothus ophiochilus is an erect shrub reaching a maximum of convert 2 m ft but generally shorter. The young twigs are reddish and grow gray with age. The tiny evergreen leaves grow opposite on the branches and sometimes grow in clusters, and rarely reach a centimeter ... more details
File West African Craton.svg thumb right 300px West Africa Tuareg Shield to the east of the West African craton File Manzaz.jpg thumb 300px This NASA Landsat image shows small scoria cones and lava flows of the Manzaz volcanic field in the Hoggar volcanic district of Algeria . The volcanic field covers an area of 1500 sq km, overlying Precambrian metamorphic and plutonic rocks of the Tuareg shield. Many cones are breached, and the dominantly basaltic and basanitic volcanic products are rich in peridotite and pyroxenite xenoliths and megacrysts. The youngest volcanoes rest on Neolithic terraces and are of Holocene age. The Tuareg Shield is an area lying between the West African craton and the Saharan Metacraton in West Africa . It has complex geology, reflecting the collision between these cratons and later events. It covers parts of Algeria , Niger and Mali . Origins The shield is mainly composed of Archean or Paleoproterozoic terrane s and Neoproterozoic terranes that amalgamated during the Pan African orogeny when the West African craton and the Saharan metacraton converged. The shield originated in oceanic island arc s that formed on the cratons during 900 Ma to 680 Ma, of which relics remain as thrust sheets on top of more rigid bodies. ref name Foulger2005 In Mali, the Tilemsi belt is a complex of intraoceanic arcs that formed above a subduction zone sloping down to the east and were accreted to the shield during the Pan African orogeny . ref name Tollo2004 The western part of the Hoggar massif is made of material from the Pharusian Ocean including oceanic basalts, arc volcanic and sedimentary rocks and sediments that were shed into the Pharusian Ocean by the West African craton and the eastern Hoggar. ref cite book page 237 url http books.google.ca books?id CI9Ig7DGvTMC&pg PA237 title Continents and supercontinents first1 John James William last1 Rogers first2 M. last2 Santosh publisher Oxford University Press US year 2004 ISBN 0195165896 ref Fracturing During ... more details
Pumice a fine grained, extremely vesicular volcanic rock Pyroxenite a coarse grained plutonic rock composed ... from volcanic ash Pyroxenite Websterite a type of pyroxenite , composed of clinoproxene and orthopyroxene ... more details
diagram for peridotite and pyroxenite, based on proportions of olivine and pyroxene. The pale ... at higher pressures to depths of 60 km or so , and garnet at yet higher pressures. Pyroxenite ... more details
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