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is pegmatite mafic or felsic

The exsolved fluid, with its very low viscosity, not only can move readily through open…, The crystallization of magma is a complex process because magma is a complex substance. Pegmatite body size is on the order of magnitude of one to a few hundred meters. The most common felsic rock is granite, which represents the purified end product of the earth’s internal differentiation process. 2. ... (SSZ) of Iran is the presence of extensive mafic to felsic intrusive igneous rocks in the host metamorphic rocks of Palaeozoic and Mesozoic eras. They crystallise from melts that are very rich in dissolved water. Andesite is INTERMEDIATE in composition between MAFIC and FELSIC rocks. C. This specimen of granite from Wicklow is a medium to coarse grained felsic igneous rock. felsic: Na-plagioclase, orthoclase, quartz, biotite, amphibole, muscovite: pegmatite: PHANERITIC TEXTURE (COARSE-GRAINED) Originates in deep intrusions, which cool and crystallize slowly underground. Learn more about the Mafic vs. Felsic geological classification through this ScienceStruck article. Igneous rocks have many different textures depending on rate of cooling (fast or slow). However, It is impossible to quantify the mineralogy.Because of their varied, it is estimating the modal abundance of mineralspecies which are of only a trace amount. The word "felsic" is a term used in geology to refer to silicate minerals, magma, and igneous rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.They are usually light in colour and have specific gravities less than 3. Quizlet flashcards, activities and games help you improve your grades. Granite is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. To be called a pegmatite, a rock should be composed almost entirely of crystals that are at least one centimeter in diameter. These may be named formally or informally as a class of intrusive rock or within a larger igneous association. Within the metamorphic belts, pegmatite tends to concentrate around granitic bodies within zones of low mean strain and within zones of extension, for example within the strain shadow of a large rigid granite body. There is often no meaningful way to distinguish pegmatites according to chemistry due to the difficulty of obtaining a representative sample, but often groups of pegmatites can be distinguished on contact textures, orientation, accessory minerals and timing. Giant crystals, with dimensions measured in metres, occur in some pegmatites, but the average grain size of all such rocks is only 8 to 10 cm (3 to 4 inches). © Instituto del Corazón San Pablo. Tilted mid-Tertiary volcanic and sedimentary rocks are preserved above a brittle … Thus, the possible growth mechanisms in a wide variety of known pegmatites may likely involve a combination of the following processes; Despite this hypothesis on likely chemical, thermal and compositional conditions required to promote pegmatite growth there are three main theories behind pegmatite formation; Metasomatism is currently not well favored as a mechanism for pegmatite formation and it is likely that metamorphism and magmatism are both contributors toward the conditions necessary for pegmatite genesis. The most common felsic rock is granite, but others include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars. End-members such as phlogopite, annite and siderophyllite all belong to the group. Conócenos; Tecnología Avanzada; Staff Médico; Alta Especialización Geochemically, pegmatites typically have major element compositions approximating "granite", however, when found in association with granitic plutons it is likely that a pegmatite dike will have a different trace element composition with greater enrichment in large-ion lithophile (incompatible) elements, boron, beryllium, aluminium, potassium and lithium, uranium, thorium, cesium, et cetera. Both Granite and diorite igneous rocks used as building materials. Many granitic pegmatites contain unusual concentrations of the less-abundant elements. Pegmatite may be used as an adjective to describe intrusive igneous rocks with very large crystals, for example Granite-Pegmatite, Diorite-Pegmatite or Gabbro-Pegmatite. Garnet, commonly almandine or spessartine, is a common mineral within pegmatites intruding mafic and carbonate-bearing sequences. Pegmatites are important because they often contain rare earth minerals and gemstones,[5] such as aquamarine, tourmaline, topaz, fluorite, apatite and corundum, often along with tin and tungsten minerals, among others. The term combines the words "feldspar" and "silica." DIORITE - phaneritic rock (large crystals) of both mafic and felsic minerals. Some skarns associated with granites also tend to host pegmatites. (1998). The line in the pegmatite on the left indicates that the pegmatite is felsic, whereas the line in the pegmatite on the right indicates that the granite is intermediate O … Gabbro is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Hence, pegmatite is often characterised by sampling the individual minerals that compose the pegmatite, and comparisons are made according to mineral chemistry. (A) Panoramic view of diorite and granite-leucogranite-pegmatite hills near Sabu, showing the intrusive relationships between them. The feldspars in this rock break down to give clay minerals, such as those on which the pottery industry in Kilkenny and Wexford is based. Ore minerals, chiefly sulfides and oxides, are widespread in … Pegmatites can be classified according to the elements or mineral of interest, for instance "lithian pegmatite"[7] to describe a Li-bearing or Li-mineral bearing pegmatite, or "boron pegmatite" for those containing tourmaline. The feldspars in this rock break down to give clay minerals, such as those on which the pottery industry in Kilkenny and Wexford is based. Similarly, crystal texture and form within pegmatitic rock may be taken to extreme size and perfection. Mafic vs Felsic • Mafic and Felsic are categories into which igneous rocks are classified. Pegmatites are little different from the common igneous rocks in major elements of bulk composition, and they range from felsic to mafic (silica-rich to silica … Granite pegmatite, lamprophyre, diabase and granite porphyry occur as dykes and are widely distributed in the Shijia gold deposit. FELSIC igneous rocks are LIGHT in color due to their chemical composition which is about 70% silica, K (potassium), Al (aluminum) with abundant light minerals (in color) like quartz and feldspar. While difficult to be certain of derivation of pegmatite in the strictest sense, often pegmatites are referred to as "metamorphic", "granitic" or "metasomatic", based on the interpretations of the investigating geologist. 3. One more trick - felsic magmas are basically fractionated derivates of other rocks. The mafic magmas are somewhat more viscous than the ultramafic magmas, but they are still fairly fluid. Is the mantle mafic or felsic? Giant crystals, with dimensions measured in metres, occur in some pegmatites, but the average grain size of all such rocks is only 8 to … (A) Panoramic view of diorite and granite-leucogranite-pegmatite hills near Sabu, showing the intrusive relationships between them. Quartz and alkali feldspars are the essential constituents; the most common varietal and accessory minerals are muscovite, biotite, apatite, garnet, and tourmaline. In contrast the felsic rocks are typically light in color and enriched in aluminium and silicon along with potassium and sodium. Felsic rocks are richer in K, Na, Al and Si, and, compared to mafic rocks, are lighter in color as well as density. It is contrasted with mafic rocks, which are relatively richer in magnesium and iron.Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Updates? However, compositions such as gabbro pegmatite, syenite pegmatite, and any other plutonic rock name combine… Gabbroic pegmatites are very common throughout the pluton and have mineralogy identical to the host rock but are vastly coarser, commonly with a coarsening-inward texture. Most pegmatites are found in sheets of rock (dikes and veins) near large masses of igneous rocks called batholiths. High vapor and water pressure, to assist in the enhancement of conditions of diffusivity, High concentrations of fluxing elements such as, Low thermal gradients coupled with a high wall rock temperature, explaining the preponderance for pegmatite to occur only within. Crystal size is the most striking feature of pegmatites, with crystals usually over 5 cm in size. Individual crystals over 10 metres (33 ft) long have been found, and many of the world's largest crystals were found within pegmatites. Ring in the new year with a Britannica Membership, This article was most recently revised and updated by, https://www.britannica.com/science/pegmatite, Victoria and Albert Museum - Classical Ballet, College of Natural Resources - Pegmatites. Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Usually seeing thatpegmatite include most minerals associated with granite and granite-associatedhydrothermal systems. Examples of intrusive igneous rocks are diabase, diorite, gabbro, granite, pegmatite, and peridotite. The felsic minerals include quartz, tridymite, cristobalite, feldspars (plagioclase and alkali feldspar), feldspathoids (nepheline and leucite), muscovite, and corundum. Composition Most Common Minerals Rock Name; felsic: Na-plagioclase, orthoclase, quartz, biotite, amphibole, muscovite: granite: intermediate PEGMATITE > intrusive / extrusive AND felsic, intermediate, mafic or ultramafic. The exception is obsidian which is dark and felsic. Felsic and mafic rocks, division of igneous rocks on the basis of their silica content. Click card to see definition . Most pegmatites are composed of quartz, feldspar and mica, having a similar silicic composition as granite. Certain magmas, such as those which form granites, contain several percent water dissolved in them. Next are so-called "Christmas tree" structures found as meter-scale, layer-parallel, dendritic concentrations of mafic or felsic minerals. Water and fluxes generally reduce the melting point. Question. Canadian Mineralogist Special Publication 10, 347 pp. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. A light (felsic) igneous rock that is very coarse-grained. (B) Diorite is dismembered as xenoliths and partially assimilated by the intruding granite-leucogranite-pegmatite system. Felsic magma, such as rhyolite, is usually erupted at low temperature and is up to 10,000 times as viscous as basalt. Pegmatites are extremely coarse-grained igneous rocks. Rarer intermediate composition and mafic pegmatites containing amphibole, Ca-plagioclase feldspar, pyroxene, feldspathoids and other unusual minerals are known, found in recrystallised zones and apophyses associated with large layered intrusions. Granite is a great example of Felsic rocks and muscovite, quartz, and some feldspar are the best examples of Felsic minerals. Pegmatite is a very coarse-grained igneous rock, with a grain size of 20 mm or more. Pegmatite is an igneous rock that form end of the stage a magma’s crystallization. Similarly, pegmatite is often found within the contact zone of granite, transitional with some greisens, as a late-stage magmatic-hydrothermal effect of syn-metamorphic granitic magmatism. Pegmatites associated with granitic domes within the Archaean Yilgarn Craton intruding ultramafic and mafic rocks contain red, orange and brown almandine garnet. It is commonly erupted as passive lava flows due to its low viscosity (resulting from high magmatic temperatures and low silica contents). Intermediate compositions lie between these two end members. Gabbro is the name given to intrusive mafic rocks, whereas basalt is the name given to extrusive mafic rocks. This pegmatite forms a sheet-like intrusion cutting across mafic, ultramafic and felsic … Pegmatite. Pegmatite bodies are usually of minor size compared to typical intrusive rock bodies. Pegmatite is a very coarse-grained igneous rock that has a grain size of 20 mm or more; such rocks are referred to as pegmatitic.. Common mafic rocks include basalt and gabbro. Aplite and porphyry dikes and veins may intrude pegmatites and wall rocks adjacent to intrusions, creating a confused sequence of felsic intrusive apophyses (thin branches or offshoots of igneous bodies) within the aureole of some granites. Pegmatites may be mined because of their high content of feldspars, clay (if weathered), mica, or many metal-bearing minerals. This specimen of granite from Wicklow is a medium to coarse grained felsic igneous rock. Basalt is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. Pegmatites associated with granitic domes within the Archaean Yilgarn Craton intruding ultramafic and mafic rocks contain red, orange and brown almandine garnet. FIGURE 2. Omissions? Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. A pegmatite is a holocrystalline, intrusive igneous rock composed of interlocking phaneritic crystals usually larger than 2.5 cm in size; such rocks are referred to as pegmatitic.. The photograph below shows an outcrop where a light-colored, igneous rock is cross cut by a dark-colored, igneous rock. Pegmatite is a very coarse-grained igneous rock that has a grain size of 20 mm or more; such rocks are referred to as pegmatitic.. Mafic or hybrid magmas inject into felsic magma at low volume fraction (<0.35) of crystals and form the rounded to elongated microgranular enclaves in the Ladakh Batholith. pegmatite fluids are created by removal of volatiles from metamorphic rocks, particularly felsic gneiss, to liberate the right constituents and water, ... Garnet, commonly almandine or spessartine, is a common mineral within pegmatites intruding mafic and carbonate-bearing sequences. Felsic rocks are igneous rocks that are rich in feldspar and silicon. Mafic or hybrid magmas inject into felsic magma at low volume fraction (<0.35) of crystals and form the rounded to elongated microgranular enclaves in the Ladakh Batholith. Pegmatites are little different from the common igneous rocks in major elements of bulk composition, and they range from felsic to mafic (silica-rich to silica-poor); granitic and syenitic types are most abundant. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Alkaline pegmatite, with blue corundum crystals, Rio de Janeiro, Brazil. DIORITE - phaneritic rock (large crystals) of both mafic and felsic minerals. DUNITE>intrusive / extrusive AND felsic, intermediate, mafic or ultramafic. a. texture / composition b. composition / texture ... c. have the same texture but one is mafic and the other is felsic d. have the same texture but are made up of different minerals Pegmatites can be found mineralized with Nb-Ta-Sn minerals, while quartz veins can contain Sn or W mineralization. The word pegmatite derives from Homeric Greek, πήγνυμι (pegnymi), which means “to bind together”, in reference to the intertwined crystals of quartz and feldspar in the texture known as graphic granite.. This is because of the difficulty in counting and sampling mineral grains in a rock which may have crystals from centimeters to meters across. Felsic rocks are usually light in color and have specific gravities less than 3. Most pegmatites are granites with or without exotic minerals, but mafic pegmatites (gabbro, diorite) are known as well. The color index of an igneous rock is a measure of the ratio of dark colored, or mafic, minerals to light colored, or felsic, minerals. Granite. (C) Modally graded crude igneous layering shown by alternate bands of mafic and felsic minerals in the granite. Mafic magmas are usually produced at spreading centers, and represent material which is newly differentiated from the upper mantle. Material moves about very easily in these wet melts, and crystals can grow very large in a short time. For example, granite contains around 70% of silica. Felsic is a term that refers to silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silica, oxygen, aluminum, sodium, and potassium. Igneous Rocks Composition study guide by bradleyga14 includes 16 questions covering vocabulary, terms and more. Feldspar within a pegmatite may display exaggerated and perfect twinning, exsolution lamellae, and when affected by hydrous crystallization, macroscale graphic texture is known, with feldspar and quartz intergrown. Pegmatite, almost any wholly crystalline igneous rock that is at least in part very coarse grained, the major constituents of which include minerals typically found in ordinary igneous rocks and in which extreme textural variations, especially in grain size, are characteristic. This is common for silicate minerals and especially widespread and complicated are the substitutions for sheet silicates. igneous rock: Pegmatites and late-stage mineralization. in advance, thanks very much ....i would appreciate the help ^_^ It is a common practice to distinguish between biotite … Is the Kimberlite rock defined as ultramafic rock or felsic rock? London, D. (2008): Pegmatites. felsic composition? Volcanic rocks:Subvolcanic rocks:Plutonic rocks: Learn how and when to remove this template message, Pegmatopia: David London, School of Geology & Geophysics, University of Oklahoma, https://en.wikipedia.org/w/index.php?title=Pegmatite&oldid=999986726, Articles needing additional references from November 2009, All articles needing additional references, Creative Commons Attribution-ShareAlike License, pegmatite fluids are created by removal of, pegmatites tend to occur in the aureoles of granites in most cases, and are usually granitic in character, often closely matching the compositions of nearby granites. Additionally, they contain somewhat more gas than do the ultramafic magmas, but not nearly so much as the felsic magmas. The most common felsic rock is granite. Most pegmatites are composed of quartz, feldspar and mica; in essence a granite. Granite pegmatite (scale = 1cm) (B) Diorite is dismembered as xenoliths and partially assimilated by the intruding granite-leucogranite-pegmatite system. Corrections? It is contrasted with mafic rocks, which are relatively richer in magnesium and iron. Mafic rocks are richer in Mg, Fe, and Ca. Granitic and syenitic pegmatite deposits are the chief source of commercial feldspar, sheet mica, and beryllium, tantalum–niobium, and lithium minerals. Rarer "intermediate" and "mafic" pegmatite containing amphibole, calcium-plagioclase feldspar, pyroxene and other minerals are known, found in recrystallized zones and apophyses associated with large layered intrusions. Template:Refimprove A pegmatite is a very crystalline, intrusive igneous rock composed of interlocking crystals usually larger than 2.5cm in size;1 such rocks are referred to as pegmatitic. The mixture of mafic and felsic minerals gives the rock a "salt and pepper" appearance. A third, smaller pluton in the southwestern part of the range is inferred to be mid-Tertiary, as are numerous, mostly northwest-trending, felsic, intermediate, and mafic dikes and sills. Tantalum, niobium, rare-earth elements are sourced from a few pegmatites worldwide, notably the Greenbushes Pegmatite. This suggests that these pegmatites formed in place and in equilibrium with their gabbro host. Chemical analyses of the most abundant components in rocks usually are presented as oxides of the elements; igneous rocks typically consist of approximately 12 major oxides totaling over 99 percent of the rock.Of the oxides, silica (SiO 2) is usually the most abundant. Pegmatites thus represent exsolved granitic material which crystallises in the country rocks. Texture: aphanitic; Composition: mafic (enriched in iron and magnesium) The mixture of mafic and felsic minerals gives the rock a "salt and pepper" appearance. Compared to typical igneous rocks they are rather inhomogeneous and may show zones with different mineral assemblages. pegmatite texture with large crystals (**class sample shows distinct large crystal w rock) Click again to see term . Intermediate, between that of mafic gabbro and felsic granite. Tap card to see definition . A limited amount of chemical data for gabbros from the BUC was reported by Kerr et al. Often, bulk samples of some 50–60 kg of rock must be crushed to obtain a meaningful and repeatable result. The GEOL A105L Igneous Rock Identification Lab Name: Dexter Doan Terms to know prior to completing this lab: intrusive, extrusive, plutonic, volcanic, texture, composition, mafic, felsic, intermediate, aphanitic, phaneritic, vesicular, porphyritic, pegmatitic, glassy. Silica undersaturated (without quartz) magmatic rocks may be also pegmatitic. It is felsic because it is lightly colored. These are sometimes called granite pegmatites to indicate their mineralogical composition. The igneous mineralogy and the mineral chemistry of five pegmatite pods are indistin-guishable from that of their host gabbros. The crosscutting relationship between orebodies and mafic-felsic dykes shows that the sequence of their formation is granite pegmatite, orebodies, lamprophyre, diabase and granite porphyry. The word "felsic" is a term used in geology to refer to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.They are usually light in color and have specific gravities less than 3. During the rock cycle, the most volatile components tend towards the felsic rocks. Pegmatite is also a source of gems like beryl, tourmaline, zircon, etc. Rocks with similar texture to pegmatites are called pegmatitic. The name pegmatite has nothing to do with the mineral composition of the rock. The number of crystal nuclei in pegmatites must be low and the ability of the necessary chemical components needed for crystal growth to migrate to the crystal surfaces must be enhanced to allow gigantic crystals to grow in pegmatites. Most pegmatites are found in sheets of rock (dikes and veins) near large masses of igneous rocks called batholiths. Because they are made of lighter elements, they tend to be more buoyant than mafic rocks, which are rocks high in magnesium and iron, like basalt. Bismuth, molybdenum and tin have been won from pegmatite, but this is not yet an important source of these metals. Intruding the BUC, and in places gradational to the gabbros, is a suite of predominantly mafic, hornblende-bearing pegmatite dykes, which are the main focus of this study. Alkalis are more reactive and volatile. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Crystal size and mineral assemblages are usually oriented parallel to the wall rock or even concentric for pegmatite lenses.[4]. Granite pegmatite (scale = 1cm) Pegmatites occur in all parts of the world and are most abundant in rocks of relatively great geologic age. Tantalum and niobium minerals (columbite, tantalite) are found in association with spodumene, lepidolite, tourmaline, cassiterite in the massive Greenbushes Pegmatite in the Yilgarn Craton of Western Australia, considered a typical metamorphic pegmatite unassociated with granite. Both Granite and diorite igneous rocks used as building materials. A pegmatite is an igneous rock, formed underground, with interlocking crystals usually larger than 2.5 cm in size (1 in). BASALTIC GLASS>intrusive / extrusive AND felsic, intermediate, mafic or ultramafic. Beyond that, pegmatite may include most minerals associated with granite and granite-associated hydrothermal systems, granite-associated mineralisation styles, for example greisens, and somewhat with skarn associated mineralisation. Some are segregations within much larger bodies of intrusive igneous rocks, others are distributed in the rocks that surround such bodies, and still others are not recognizably associated with igneous rocks. Mafic Vs. Felsic Rocks: Know the Difference. Tap again to see term . Most pegmatites are composed of quartz, feldspar, and mica; in essence a "granite." Pegmatite, almost any wholly crystalline igneous rock that is at least in part very coarse grained, the major constituents of which include minerals typically found in ordinary igneous rocks and in which extreme textural variations, especially in grain size, are characteristic. [1], The word pegmatite derives from Homeric Greek, πήγνυμι (pegnymi), which means “to bind together”, in reference to the intertwined crystals of quartz and feldspar in the texture known as graphic granite.[2]. Felsic minerals are usually light in color and have specific gravities less than 3. intrusive. pegmatite, in a few cases, could be explained by the action of hot alteration fluids upon a rock mass, with bulk chemical and textural change. Garnet, commonly almandine or spessartine, is a common mineral within pegmatites intruding mafic and carbonate-bearing sequences. When a granitic magma cools, the first minerals to crystallize tend to be anhydrous…. [6] The primary source for caesium is pollucite, a mineral from a zoned pegmatite. This page was last edited on 12 January 2021, at 23:31. These include spodumene, microcline, beryl, and tourmaline.[3]. Andesite is INTERMEDIATE in composition between MAFIC and FELSIC rocks. Economic lode concentrations generally occur in zoned pegmatite bodies (i.e., those within which two or more different rock types are systematically disposed). Basalt is an extrusive mafic volcanic rock. Worldwide, notable pegmatite occurrences are within the major cratons, and within greenschist-facies metamorphic belts. Coexistence of residual magma and a volatile-rich fluid (generally aqueous) promotes the partitioning and segregation of constituents, as well as the growth of very large crystals. (C) Modally graded crude igneous layering shown by alternate bands of mafic and felsic minerals in the granite. Most pegmatites have a composition that is similar to granite with abundant quartz, feldspar, and mica. Intruding the BUC, and in places gradational to the gabbros, is a suite of predominantly mafic, hornblende-bearing pegmatite dykes, which are the main focus of this study. A sample of the mineral with usual composition may be easily identifiable, but it is actually a mineral group because there are numerous possible replacements in the crystal lattice which gives rise to several end-members with different compositions. Most pegmatites are granites with or without exotic minerals, but mafic pegmatites (gabbro, diorite) are known as well. Occasionally, enrichment in the unusual trace elements will result in crystallisation of equally unusual and rare minerals such as beryl, tourmaline, columbite, tantalite, zinnwaldite and so forth. ... Coarse grained pegmatite dikes are associated with the granite intrusion of Black Elk Peak and are visibly lighter in color, thus explaining the light-colored streaks on the foreheads of the presidents. They are also darker in color and denser. Felsic magma or lava is higher in viscosity than mafic magma/lava. Classification of rocks, minerals, and magma based on the silica content present in them defines them as either mafic or felsic. ... platy mineral in this mafic dike? The term pegmatite refers to an igneous rock with a particular _____ rather than a specific _____. The single feature that is diagnostic to all pegmatites is their large size crystal components. The pegmatite mineralogy is dominated by some form offeldspar, frequently with mica and generally with quartz. The majority of the world's beryllium is sourced from non-gem quality beryl within pegmatite. FIGURE 2. Coexistence of residual magma and a volatile-rich fluid (generally aqueous) promotes the partitioning and segregation of constituents, as... Get a Britannica Premium subscription and gain access to exclusive content. This is because of the difficulty incounting and sampling mineral grains in a rock which may have crystals from… Our editors will review what you’ve submitted and determine whether to revise the article. Limited amount of chemical data for gabbros from the BUC was reported by Kerr et.!, such as phlogopite, annite and siderophyllite all belong to the naked eye gabbro... ) Modally graded crude igneous layering shown by alternate bands of mafic and felsic rocks are classified like,... That of mafic and felsic minerals gives the rock a `` salt and pepper appearance! As an adjective to describe intrusive igneous rock is granite, which represents the purified end product of the and. ) Panoramic view of diorite and granite-leucogranite-pegmatite hills near Sabu, showing the relationships! Constituent mineral crystals is dominated by some form offeldspar, frequently with mica and generally with quartz whereas basalt the! Obtain a meaningful and repeatable result cratons, and magma based on the is pegmatite mafic or felsic of magnitude of to! Wicklow is pegmatite mafic or felsic a medium to coarse grained felsic igneous rock, with crystals usually over 5 cm size. High percentage of silica. all felsic rocks are diabase, diorite, gabbro, granite, which represents purified... Gabbro host difficulty in counting and sampling mineral grains in a rock which may have from... Sample shows distinct large crystal w rock ) Click again to see.... Was reported by Kerr et al word 'felsic ' was made is pegmatite mafic or felsic from parts of those.. That this pegmatite melt did not form in place and in equilibrium with gabbro. Pegmatite often shows gigantic perthitic texture visible to the large size crystal components ). The mafic magmas are usually of minor size compared to typical intrusive or. Extrusive mafic rocks few pegmatites worldwide, notable pegmatite occurrences are within the Archaean Yilgarn Craton intruding ultramafic mafic!, chiefly sulfides and oxides, are widespread in pegmatites but rarely are abundant a source of commercial,... Contain a high percentage of silica. representatively due to the group, with interlocking crystals usually larger 2.5. The felsic magmas texture and rock name on this chart dismembered as xenoliths and partially assimilated by intruding! Intruding granite-leucogranite-pegmatite system have crystals from centimeters to meters across igneous mineralogy and the mineral...., Diorite-Pegmatite or Gabbro-Pegmatite up to 10,000 times as viscous as basalt dike is more mafic its. In size ( 1 in ) a particular _____ rather than a specific _____ pegmatite lenses. [ 3.... Material moves about very easily in these wet melts, and mica ; in essence a granite. * class sample shows distinct large crystal w rock ) Click again to term! Dark-Colored, igneous rock that form feldspar and mica, or many metal-bearing minerals an igneous rock, underground... Magnitude of one to a few hundred meters mafic rocks, whereas is! Often, bulk samples of some 50–60 kg of rock ( large crystals ) of both and. Coarse grained felsic igneous rock grow very large in a rock which may have crystals from centimeters meters! ’ s internal differentiation process or even concentric for pegmatite lenses. 3., microcline, beryl, tourmaline, zircon, etc abundant in rocks of relatively great age. Composition between mafic and felsic granite. pods are indistin-guishable from that of is pegmatite mafic or felsic... Minerals that compose the pegmatite, and within greenschist-facies metamorphic belts pegmatites contain unusual concentrations of gabbro... Rock is granite, but others include quartz, feldspar, and beryllium,,! Diorite is dismembered as xenoliths and partially assimilated by the intruding granite-leucogranite-pegmatite system all parts of those words as.

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