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Ijolite
Ijolite is an igneous rock consisting essentially of nepheline and augite. Ijolite is a rare rock type of considerable importance from a mineralogical and petrological standpoint. The word is derived from the first syllable of the Finnish words such as ''Iivaara'', ''Iijoki'' and '' Ii'', all geographical names in Finland, and the Ancient Greek ''Xiflos'', a stone. Ijolite occurs in various parts of the Kainuu region of eastern Finland and in the Kola Peninsula of northwest Russia on the shores of the White Sea. Ijolite was first defined and named by Finnish geologist Wilhelm Ramsay. The pyroxene is , yellow or green, and is surrounded by formless areas of nepheline. The accessory minerals are apatite, cancrinite, calcite, titanite and schorlomite, a dark-brown titaniferous variety of melanite-garnet. This rock is the plutonic and holo-crystalline analogue of the nephelinites -volcanic equivalent and nepheline-dolerites; it bears the same relation to them as the nepheline syenit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garnet
Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. Garnet minerals, while sharing similar physical and crystallographic properties, exhibit a wide range of chemical compositions, defining distinct species. These species fall into two primary solid solution series: the pyralspite series (pyrope, almandine, spessartine), with the general formula [Mg,Fe,Mn]3Al2(SiO4)3; and the ugrandite series (uvarovite, grossular, andradite), with the general formula Ca3[Cr,Al,Fe]2(SiO4)3. Notable varieties of grossular include Grossular#Hessonite, hessonite and tsavorite. Etymology The word ''garnet'' comes from the 14th-century Middle English word ''gernet'', meaning 'dark red'. It is borrowed from Old French ''grenate'' from Latin language, Latin ''granatus,'' from ''granum'' ('grain, seed'). This is possibly a reference to ''mela granatum'' or even ''pomum granatum'' ('pomegranate', ''Punica granatum''), a plant whose fruits conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilhelm Ramsay
Wilhelm Ramsay (20 January 1865 – 6 January 1928) was a Finnish geologist. He became a member of the Royal Swedish Academy of Sciences in 1914 and in 1915 was accepted into the Royal Physiographic Society in Lund. He coined the terms Fennoscandia (1900) and Postjotnian (1909). Ramsay also coined the term ijolite. Together with Jakob Sederholm, Ramsay was a student of Fredrik Johan Wiik. Pentti Eskola was a student of Ramsay. Personal life Ramsay was a Swedish-speaking Finn and belonged to the Ramsay noble family of Scottish origin. His mother Emmy Tham was from Falun Falun () is a city and the seat of Falun Municipality in Dalarna County, Sweden, with 37,291 inhabitants in 2010. It is also the capital of Dalarna County. Falun forms, together with Borlänge, a metropolitan area with just over 100,000 inhabit ..., Sweden. Mathematician August Ramsay was his brother. References 1865 births 1928 deaths Finnish geologists Tectonicists Members of the Royal Swe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apatite
Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of Hydroxide, OH−, Fluoride, F− and Chloride, Cl− ion, respectively, in the crystal. The formula of the admixture of the three most common Endmember (mineralogy), endmembers is written as Calcium, Ca10(Phosphate, PO4)6(OH,F,Cl)2, and the crystal unit cell formulae of the individual minerals are written as Ca10(PO4)6(OH)2, Ca10(PO4)6F2 and Ca10(PO4)6Cl2. The mineral was named apatite by the German geologist Abraham Gottlob Werner in 1786, although the specific mineral he had described was reclassified as fluorapatite in 1860 by the German mineralogist Karl Friedrich August Rammelsberg. Apatite is often mistaken for other minerals. This tendency is reflected in the mineral's name, which is derived from the Greek word ἀπατάω (apatáō), which means ''to deceive''. Geology Apatite is very common as an accessory mineral in igneous and metamorphic roc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fort Benton, Montana
Fort Benton is a city in and the county seat of Chouteau County, Montana, United States. Established in 1846, Fort Benton is the oldest continuously occupied settlement in Montana. Fort Benton was the most upstream navigable port on the Mississippi River System, and is considered "the world’s innermost port". The city's waterfront area, the most important aspect of its 19th century growth, was designated the Fort Benton Historic District, a National Historic Landmark, in 1961. The population was 1,449 at the 2020 census. History Established in 1846 as Fort Lewis and relocated 15 miles downstream in 1847 by Alexander Culbertson, who worked for Auguste Chouteau and Pierre Chouteau, Jr. of St. Louis, the original fort was the last fur trading post on the Upper Missouri River, Chouteau County Courthouse, 2009 which soon made it an important economic center. For 30 years, the port attracted steamboats carrying goods, merchants, gold miners and settlers, coming from New O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leucite
Leucite (from the Greek word ''leukos'' meaning white) is a rock-forming mineral of the feldspathoid group, silica-undersaturated and composed of potassium and aluminium tectosilicate KAlSi2O6. Crystals have the form of cubic icositetrahedra but, as first observed by Sir David Brewster in 1821, they are not optically isotropic, and are therefore pseudo-cubic. Goniometric measurements made by Gerhard vom Rath in 1873 led him to refer the crystals to the tetragonal system. Optical investigations have since proved the crystals to be still more complex in character, and to consist of several orthorhombic or monoclinic individuals, which are optically biaxial and repeatedly twinned, giving rise to twin-lamellae and to striations on the faces. When the crystals are raised to a temperature of about 500 °C they become optically isotropic and the twin-lamellae and striations disappear, although they reappear when the crystals are cooled again. This pseudo-cubic character of le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phonolite
Phonolite is an uncommon shallow intrusive or extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneous rock trachyte that contains nepheline or leucite rather than quartz. It has an unusually high (12% or more) Na2O + K2O content, defining its position in the TAS classification of igneous rocks. Its coarse grained (phaneritic) intrusive equivalent is nepheline syenite. Phonolite is typically fine grained and compact. The name ''phonolite'' comes from the Ancient Greek meaning "sounding stone" due to the metallic sound it produces if an unfractured plate is hit; hence, the English name ''clinkstone'' is given as a synonym. Formation Unusually, phonolite forms from magma with a relatively low silica content, generated by low degrees of partial melting (less than 10%) of highly aluminous rocks of the lower crust su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nepheline Syenite
Nepheline syenite is a holocrystalline Intrusion, plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are also known. Phonolite is the fine-grained Extrusive rock, extrusive equivalent. Petrology Nepheline syenites are silica-undersaturated and some are peralkaline (terms discussed in igneous rock). Nepheline is a feldspathoid, a solid-solution mineral, that does not coexist with quartz; rather, nepheline would react with quartz to produce alkali feldspar. They are distinguished from syenites not only by the presence of nepheline but also by the occurrence of many other minerals rich in alkalis and in rare earths and other incompatible elements. In nepheline syenites, alkali feldspar dominates, commonly represented by orthoclase and the exsolved lamellar albite, form perthite. In some rocks the potash feldspar, in others the soda f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nephelinite
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite). If olivine is present, the rock may be classified as an olivine nephelinite. Nephelinite is dark in color and may resemble basalt in hand specimen. However, basalt consists mostly of clinopyroxene (augite) and calcic plagioclase. Basalt, alkali basalt, basanite, tephritic nephelinite, and nephelinite differ partly in the relative proportions of plagioclase and nepheline. Alkali basalt may contain minor nepheline and does contain nepheline in its CIPW normative mineralogy. A critical ratio in the classification of these rocks is the ratio nepheline/(nepheline plus plagioclase). Basanite has a value of this ratio between 0.1 and 0.6 and also contains more than 10% olivine. Tephritic nephelinite has a value between 0.6 and 0.9. Nephelinite has a value greater than 0.9. Le Maitre (2002) defines and discusses these and other criteria in the classification of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonic
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form ''intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March 27, 2017.Igneous intrusive rocks, accessdate: March 27, 2017.Britannica.comintrusive rock , geology , Britannica.com accessdate: March 27, 2017. Intrusion is one of the two ways igneous rock can form. The other is extrusion, such as a volcanic eruption or similar event. An intrusion is any body of intrusive igneous rock, formed from magma that cools and solidifies within the crust of the planet. In contrast, an ''extrusion'' consists of extrusive rock, formed above the surface of the crust. Some geologists use the term plutonic rock synonymously with intrusive rock, but other geologists subdivide intrusive rock, by crystal size, into coarse-grained plutonic rock (typically formed deeper in the Earth's crust in batholiths or stocks) an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
