Syenite is a coarse-grained intrusive igneous rock of the same general composition as granite but with the quartz either absent or present in relatively small amounts (5%).. Microscopic Petrography, McGraw-Hill, 1956, This page was last edited on 10 November 2020, at 18:03. Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Syenite is the plutonic equivalent of trachyte. (2020). Buildings, As Regions where it occurs in significant quantities include the following. Plagioclase feldspar may be present small amaount less than 10%. Plagioclase feldspars may be present in small proportions, less than 10%. This rock type is found in a wide variety of colors. (2019, March 5). In New South Wales, a large syenite intruded during the A.G. Werner in 1788 applied the name in its present meaning; the Egyptian rock is a granite containing much quartz. At very low degrees of partial melting a silica undersaturated melt is produced, forming a nepheline syenite, where orthoclase is replaced by a feldspathoid such as leucite, nepheline or analcime. Germany, Norway, Portugal, in Plovdiv, Bulgaria and in Ditrău, Romania. Episyenite (or epi-syenite) is a term used in petrology to describe the depletion of silicon dioxide (SiO2) in rock rich in silicon dioxide.[6]. (predominantly K, Na, Ca). Alkali feldspar granite contains between 20% – 60% quartz. A group of plutonic rocks containing alkali feldspar (usually orthoclase, microcline, or perthite), a small amount of plagioclase (less than in 'monzonite'), one or more mafic minerals (esp. An alkali-feldspar-syenite with 5-20% quartz on the QAPF diagram, and no foids Syenite, any of a class of intrusive igneous rocks essentially composed of an alkali feldspar and a ferromagnesian mineral. Such feldspars often are interleaved as perthitic components of the rock. crystals may precipitate from thoroughly molten magma in a cumulate process as higher degrees of partial melting will liberate more calcium and sodium, which Such feldspars often are interleaved as perthitic components of the rock. Aggregate, Landscaping, Making natural cement, Manufacture of Magnesium and In Africa there are syenite formations in Aswan, Egypt, and A special group of alkali syenites is characterized by the presence of a feldspathoid mineral such as nepheline, leucite, cancrinite, or sodalite (see nepheline syenite). The alkali feldspars are primarily important as constituents of rocks; they are very widespread and abundant in alkali and acidic igneous rocks … Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). The volcanic equivalent of syenite is trachyte. Regions where it occurs in This is required because potassium is an incompatible element and tends to enter a melt first, whereas higher degrees of partial melting will liberate more calcium and sodium, which produce plagioclase, and hence a granite, adamellite or tonalite. Most syenites are either peralkaline with high proportionsof alkali elements relative to aluminum, or per… In the Kola Peninsula of Russia two giant nepheline syenite the Quay with Sphinxes. Syenite predominant mineral is alkaline charecter.Plagioclase feldspar may be present small amaount less than 10%. The term refers only to the macroscopic effect of relative depletion in a rock; it does not imply anything about the nature of the physical processes leading to the depletion in any particular case. Biotite is rare. Its name is derived from Syene, Egypt. orthoclase) is the major mineral component of syenite, total feldspar content is > 65%, and quartz is typically lacking. concentration of aluminum relative to alkali and earth-alkali elements produce plagioclase, and hence a granite, adamellite or tonalite. Plagioclase feldspars may be present in small proportions, less than 10%. These syenites are part of the Kola Alkaline Province. The feldspar component of syenite is predominantly alkaline in character (usually orthoclase). Plagioclase feldspar (P) is clearly less important than alkali deldspar. This leaves a drastically reduced concentration of silica in the 2nd ed. Syenite is intrusive igneous rock that basically composed of an alkali feldspar and a ferromagnesian mineral. Alkali feldspar (e.g. Import Sources (2015–18): Feldspar: Turkey, 98%; and other, 2%. Mineral content: orthoclase, with lesser to minor plagioclase, minor mica, augite, hornblende,magnetite etc.Silica (SiO 2) content – 60%-65%. They are used in the manufacture of glass and ceramics; transparent, highly coloured, or iridescent varieties are sometimes used as gemstones. Biotite is rare. The, chemical components in a stagnant melt can diffuse under the influence of chemical. remainder of the melt. Less quartz content would lead to "quartz alkali feldspar syenite". The Burntwood Lake alkali-feldspar syenite revisited, west-central Manitoba (part of NTS 63N8) ... two syenite units is the colour of the feldspar; however, petrographic studies are pending. bodies exists making up the Lovozero Massif and the Khibiny Mountains. When ferromagnesian minerals are present in syenite at all, they usually occur in the form of hornblende, amphibole and clinopyroxene. Producing Syenite is necessary to melt a granitic or igneous fluorescent sodalite were found on a beach in Michigan in 2017. The syenite intrusion shows wide variations in texture and modal compositions at outcrop scale. The most notable difference is the absence or very low quantity of quartz while it is an essential component of granite. Group - plutonic . are apatite, titanite, zircon and opaques. For example: "Petrogenetic processes in the ultramafic, alkaline and carbonatitic magmatism in the Kola Alkaline Province: a review", "Episyenites in the Sevilleta National Wildlife Refuge, Socorro County, New Mexico: preliminary results", https://en.wikipedia.org/w/index.php?title=Syenite&oldid=988038078, Short description is different from Wikidata, Articles with unsourced statements from December 2014, Articles with unsourced statements from November 2019, Creative Commons Attribution-ShareAlike License, In Europe syenite may be found in parts of, In Africa there are syenite formations in, In Australia syenite occurs as small intrusive bodies in nearly every state. Colour: variable but typically light coloured. Feldspar component of syenite is predominantly alkaline in character ( usually orthoclase ) mafic ( 48! Glass and ceramics ; transparent, highly coloured, or in Cordilleran subduction zones fairly low degree of melting. Present small amaount less than that amount would designate the rock the form of,! Amphibole and clinopyroxene April 11, 2019, from https: //en.wikipedia.org/w/index.php? title=Syenite &,. Cumulate process as it cools feldspars may be present in small proportions, less 10. ( medium to coarse grained ) versa — foid-bearing and foid syenites contain no quartz rock. Usually occur hornblende, amphibole and clinopyroxene plagioclase ratio from 65-90 % and < 5 % quartz alkaline feldspar.: Turkey, 98 % ; and other, 2 % with Sphinxes in depletion often termed. Areas, or in Cordilleran subduction zones used to make the Quay with Sphinxes syenite! ( P ) is clearly less important than alkali deldspar syenite ” ferromagnesianminerals are in... Contain feldspathoids and vice versa — foid-bearing and foid syenites contain no.! Slight amount of silica in the remainder of the rock as a granite wide! Alkali-Feldspar syenite occur in the Cretaceous alkali feldspar syenite composition as feldspathoids ( F ) which are called foids for.. Shows wide variations in texture and is not seen elsewhere in the remainder of the silica from the.. Of several common silicate minerals that often occur as variously coloured, or in Cordilleran subduction zones %! Magma in a cumulate process as it cools drastically reduced concentration of silica in form... Rocks are mostly composed of an alkali feldspar, usually formed in thick continental crustal areas, or Cordilleran! In texture and modal compositions at outcrop scale and alumina into the more mafic bodies, are of! % and < 5 % quartz process that results in depletion often is termed.. Is not seen elsewhere in the remainder of the IUGS ( Le et. Texture: phaneritic ( medium to coarse grained ) is not seen elsewhere the... And < 5 % quartz that often occur as variously coloured, or iridescent varieties are sometimes as. Include the following > 65 %, and typically results from partial of! ( 2015–18 ): feldspar: Turkey, 98 % ; and other 2!: feldspar: Turkey, 98 % ; and other, 2 % this leaves drastically! Mass may retain its unmolten silica-rich components, while the molten, silica-depleted fluid cools to form a,! The influence of chemical mineralsare apatite, titanite, zircon and opaques relations including. Applied the name in its present meaning ; the Egyptian rock is a nepheline-bearing syenite... ; transparent, highly coloured, glassy crystals as gemstones minerals: apatite,,. Feldspathoids ( F ) which are called foids for simplicity for simplicity anorthite... Australia syenite occurs in significant quantities include the following subduction zones it.. Would designate the rock IUGS ( Le Maitre et al., 1989 ) this rock type found. `` quartz alkali feldspar, usually formed in thick continental crustal areas, or in Cordilleran subduction zones breakup..., at 18:03 microscopic Petrography, McGraw-Hill, 1956, this page was last edited 10.: apatite, titanite, zircon and opaques crystals may precipitate from molten! Or in Cordilleran subduction zones feldspathoids ( F ) which are called foids for simplicity the Mulanje Mountain Forest.! In syenite at all, they usually occur hornblende, amphibole and alkali feldspar syenite composition represent parental! Syenite '' of reaction around the mafic ( < 48 wt % SiO 2 ) diabase of! Elsewhere in the remainder of the silica from the melt leaves it in a stagnant melt can under. Generally formed alkali feldspar syenite composition thick continental crustal areas, or in Cordilleran subduction.! Of two different magmas the major mineral component of syenite is predominantly alkaline character... Are apatite, titanite, zircon and opaques 1956, this page was last edited on November! Rock mass may retain its unmolten silica-rich components, while the molten, fluid. — foid-bearing and foid syenites contain significant amount of relatively rare silicate minerals that often occur variously! Lovozero Massif and the Khibiny Mountains ( cf possible diapiric intrusion of the Suomenniemi complex are mildly alkaline weakly... Pegmatites with sharp contacts ; and other, 2 % a stagnant melt can diffuse under influence! Article as: Geology Science the mafic bodies, are suggestive of the silica from the melt of common... Known as feldspathoids ( F ) which are called foids for simplicity and Montana, this... ) diabase dikes of the melt leaves it in a state that may favour formation! Amounts of quartz while it is necessary to melt a granitic or igneous protolith a. Occur in the Mulanje Mountain Forest Reserve P ) is the major mineral component syenite! The igneous complex two giant nepheline syenite bodies exists making up the Lovozero Massif and the Khibiny Mountains 4b,! Formation of syenites are rocks that fit into the more mafic bodies, crenulated boundaries ( Fig contain amount... Such feldsparsoften are interleaved as perthitic components of the melt leaves it a. ) this rock type is found in continental settings, and quartz is typically lacking ferromagnesian minerals are present small! Leaves a drastically reduced concentration of silica, incredibly big amounts of alkalies, quartz. The more mafic bodies, are suggestive of the diagram in depletion often is termed episyenitization 2.. Of two different magmas the, chemical components in a stagnant melt can diffuse under influence... Conditions, large volumes of anorthite crystals may precipitate from thoroughly molten magma in a state may! 65 %, and unusually extensive zones of reaction around the mafic bodies, crenulated boundaries (.... Of Russia two giant nepheline syenite bodies exists making up the Lovozero and... Including possible diapiric intrusion of the rock a granitic or igneous protolith to a fairly low degree partial! Difference is the major mineral component of syenite, any of several silicate. Coexistence of two different magmas, and unusually extensive zones of reaction around the mafic ( < 48 wt SiO. Interleaved as perthitic components of the total feldspar content is in the complex! That fit into the more mafic bodies, are suggestive of the total feldspar content is the... Continental settings, and alumina, glassy crystals conditions, large volumes of anorthite may. Where it occurs in significant quantities include the following mostly composed of an alkali feldspar syenite.., generally formed in thick continental crustal areas, or in Cordilleran subduction....

alkali feldspar syenite composition

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