Most pegmatites are found in sheets of rock (dikes and veins) near large masses of igneous rocks called batholiths. Miarolitic cavities (or miarolitic texture) are typically crystal-lined irregular cavities or vugs most commonly found in granitic pegmatites, and also in a variety of igneous rocks.The central portions of pegmatites are often miarolitic as the pegmatite dike crystallizes from the outside walls toward the center. Granite Pegmatite is a common Igneous rock What is the texture of pegmatite? Cliquez sur une vignette pour l’agrandir. pegmatite: see granite granite, coarse-grained igneous rock of even texture and light color, composed chiefly of quartz and feldspars. (also graphic texture and granophyric texture), a term that describes the physical appearance and character of magmatic rocks that exhibit close intergrowths as a result of the simultaneous crystallization of quartz and feldspar. A pegmatitic texture is one in which the mineral grains are exceptionally large. The most spectacular pegmatites contain abnormally large crystals mixed with medium sized and smaller crystals. Other articles where Pegmatitic texture is discussed: rock: Classification by grain or crystal size: 2 inches) are termed pegmatitic. 5.2 Composition 5.2.1 Mineral Content Apatite, Beryl, Feldspar, Fluorite, Garnet, Lepidolite, Quartz, Silica, Spodumene, Topaz American Mineralogist, 43, 181-207. (1958) Pegmatite phosphates and their problems. Un article de Wikipédia, l'encyclopédie libre. Examples from the Weiss Mine, Germany, show this transition. Ces fluides se concentrent dans les fissures de retrait qui se forment durant le refroissement d'une masse de magma, ce qui donne une allure filonienne aux roches pegmatitique. Vlassov et de A.I. Vous pouvez partager vos connaissances en l’améliorant (comment ?) The word "pegmatite" comes from the Greek word pegnymi, which means "to bind together," referring to the entwined feldspar and quartz crystals commonly found in the rock. Most pegmatites are found in sheets of rock (dikes and veins) near large masses of igneous rocks called batholiths. Les pegmatites sont des roches ignées intrusives formées de cristaux plus grands que 1 cm. Coarse plagioclase laths dominate with interstitial, subhedral clinopyroxene and abundant interstitial to somewhat poikilitic magnetite and ilmenite. La dernière modification de cette page a été faite le 24 octobre 2020 à 19:42. Varlamoff, N. (1958-1959) Zonéographie de quelques champs pegmatitiques de l'Afrique centrale et les classifications de K.A. Pegmatite à clinopyroxène et plagioclase : des lentilles de pyroxène forment un cumulat. 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 pegmatite mineralogy is dominated by some form offeldspar, frequently with mica and generally with quartz. Pegmatites … Crystals up to many meters long have been reported. En gros cristaux automorphes (25 x 15 cm) sans texture graphique, avec microperthites. Pegmatite (Pegmatite à texture graphique) Massif armoricain Roscoff . The water allowed the necessary elements to diffuse extra fast to the sites of crystallization. Instead, the large crystals of a pegmatite formed in a magma that was extra rich in dissolved water. pegmatite in the early 1800s to refer to a roclz with a patterned geometric intergrowth of feldspar and quartz (now commonly termed graphic granite). Faites votre choix parmi Pegmatite de photos, images, illustrations, vecteurs, symboles et vidéos libres de droits sur Adobe Stock et téléchargez-les pour vos projets créatifs. Abstract. These are concentric zones which conform roughly to the shape of the pegmatite body and differ in mineral assemblages and textures. La Société géologique de Belgique, 82, B55-B87 light color, composed chiefly of quartz and.! 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