Pegmatites are extreme igneous rocks that form during the final stage of a magmas crystallization. No one universally accepted model of pegmatite genesis has yet emerged that satisfactorily explains all the diverse features of granitic pegmatites. The shape of pegmatite bodies range from from tabular to inverted teardropshaped and range in size from several tens of meters up to a kilometer or more in extent. Jul 17, 2008 by rakovan, john the very first word to the wise column dealt with the term pegmatite rakovan 2003. The silver peak occurrence has been described by spurr,rl5 who originated the word alaskite a number of years earlier. Pegmatites sometimes occur as pocketlike inclusions in the intrusive parent rock into which they grade marginally. A pegmatite may be a segregation within an associated plutonic rock or a dike or vein that intrudes the surrounding country rock the composition range of pegmatites is similar to that of other intrusive igneous rocks and is indicated by using modifier, e. In other words, at this early stage, the provenance of the pegmatitic. Apr 15, 2015 pegmatites are generally associated with a parent granite in some way and can form at relatively deep to very shallow crustal levels. Pegmatite meaning pegmatite pronunciation pegmatite definition pegmatite explanation how to pronounce pegmatite. The english literature on these pegmatites is minor for various reasons.
Graphic granite, the defining texture of pegmatites, was singled out and illustrated by patrin 1801. Pegmatites crossword answers, clues, definition, synonyms. A preliminary deposit model for lithiumcesiumtantalum lct pegmatites. One problem is the classification of some pegmatites as nyf that contain little or no yttrium or others that contain. Mineraldeposit model for lithiumcesiumtantalum pegmatites. Goldauriferous deposits can be classified into types for which here is a list of 10 types of gold deposits. Pegmatites article about pegmatites by the free dictionary. This was especially fitting because pegmatites are one of the most important rock types or geologic environments for the production of beautiful and interesting mineral specimens. Not all pegmatite gems occur in all pegmatites most are restricted to specific varieties of pegmatites and some even. Pegmatite is a common plutonic rock, of variable texture and coarseness, that is composed of interlocking crystals of widely different sizes. It was mined for emeralds by a series of owners, which included tiffany and company, between 1894 and the 1990s.
Pegmatites do form where magmas cool relatively slowly within the earth compared to the fast cooling they would experience if they had erupted on to the earths surface. The term pegmatite was first introduced in 1801 by the french scientist r. This article surveys all the granitic pegmatites worldwide that have produced fluorite in cavities and are thus of collector interest and available for sale by mineral dealers discover the world. A petrologic assessment of internal zonation in granitic.
Less common minerals found in pegmatite include magnetite or hematite, beryl, tourmaline and garnet. Rare minerals from pegmatites attracted some of the earliest practitioners of mineralogy e. A coarsegrained granite, sometimes rich in rare elements such as uranium, tungsten, and tantalum. In recent years, the practice of beryl production through pegmatitic environments had considerably sloweddown, diminishing the economic capacity or impact of beryllium and pegmatites. One of the most interesting pegmatites is the crabtree pegmatite of western north carolina. Class ii, the rare element class, is the most mineralized and most mineralogically diverse.
Neither lithiumcesiumtantalum pegmatites nor their. Pegmatite definition is a coarse variety of granite occurring in dikes or veins. Original paper the missing link between granites and. Crystals up to many meters long have been reported. The most spectacular pegmatites contain abnormally large crystals mixed with medium sized and smaller crystals. Pegmatites definition of pegmatites by the free dictionary. In igneous rocks, the presence of large minerals tells us that the rocks cooled very slowly from their molten state to what we see today. Coarse granite known as pegmatite often breaks up in weathering, leaving large pieces of quartz and feldspar lying on the ground 6. Pegmatite definition, a coarsely crystalline granite or other highsilica rock occurring in veins or dikes.
Pegmatites synonyms, pegmatites pronunciation, pegmatites translation, english dictionary definition of pegmatites. Pegmatite article about pegmatite by the free dictionary. Pegmatites are formed as part of the cooling and crystallization process of intrusive rocks. Effects of boron, phosphorus, and fluorine david london school of geology and geophysics, university of oklahoma, norman, ok 73019, u.
This was espe cially fitting because pegmatites are one of the most important rock types or geologic environments for the pro duction of beautiful and interesting mineral specimens. Normally, within an extensive pegmatite field only a few distinct lipegmatites may be found but in some pegmatitic ter. Gembearing pegmatites are crystalline igneous rocks that are distin guished by their largesize crystals, concen trations of certain chemical elements otherwise rare in the earths crust, and var ious urjusal minerals. Internal differentiation of rareelement pegmatites. A preliminary deposit model for lithiumcesiumtantalum lct. Okunlola and oyedokun 2009 observed that the pegmatites of igbeti area in southwestern nigeria display tanb mineralization potential that is comparable to world class tanco deposits of canada and. Granitic pegmatites as sources of colored gemstones. A preliminary deposit model for lithiumcesiumtantalum. But pegmatites are associated both in time and space with other igneous rocks that formed at the same depth and show much smaller grains. Pegmatite definition of pegmatite by merriamwebster. Hauy to designate graphic, or hebraic, granite, a frequently encountered structural variety of pegmatite.
Granitic pegmatites as reflections of their sources. Introduction pegmatite the word itself sends shivers of excitement up my spine. According to schallers116 paragenetic interpretation, the pegmatites at pala, california, are alaskite in character. Dictionary grammar blog school scrabble thesaurus translator quiz more resources more from collins. Rocks that display large, granular crystal structure are called pegmatitic. Most definitions of pegmatites contain genetic interpretations. We hope that the following list of synonyms for the word pegmatites will help you to finish your crossword today. Normally, within an extensive pegmatite field only a few distinct li pegmatites may be found but in some pegmatitic terrains, especially in parts of central and southern af. Pegmatite is the premier rock type for finding large high quality gemstones, and with the exception of diamond, can produce basically the whole range of. In particular, the mineralogy and geochemistry of lct pegmatites have been studied in great detail. The major uraniferous pegmatites are identified by a central massive quartz core in deeply lateritized terrain. Lithium pegmatites remain a viable source of the metal because of its high concentration in the ores, and production from these deposits miti gates concerns about supplies from brine producers in chile and argentina. Continued jrom page 56 classification of pegmatites fnrnolucrron the natural tendency in classifying pegmatites is to use the same nomenclature as is used in rock classification, with in the case. Pegmatite definition and meaning collins english dictionary.
Lct pegmatites are also mined for ultrapure quartz, potassium feldspar, albite, and muscovite. 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. Gem bearing pegmatites geology and geography introduction pegmatite the word itself sends shivers of excitement up my spine. Mining a pegmatite is like butchering a hog these is a demand for practically everything you find. The purpose of the pegmatite page is to provide a forum for those of us interested in pegmatites pigs. They are extreme because they contain exceptionally large crystals and they sometimes contain minerals that are rarely found in other types of rocks. Pegmatite black canyon of the gunnison national park u. It is a large area of granite hills in which numerous pegmatites have been found through the years. More complex pegmatites are often zoned and can contain minerals like tourmaline, garnet, beryl, fluorite, lepidolite, spodumene, apatite, and topaz.
Edem et al geochemical signatures and mineralization potentials of precambrian pegmatites of southern obudu, bamenda massif, southeastern nigeria pegmatites exposed at agwan rimi, in north central nigeria, and concluded that the deposit holds high potential. Meaning, pronunciation, translations and examples log in dictionary. Traditionally, most beryllium was sourced from beryl which is commonlyfound in pegmatitic environments. The largest of these are found upstream from east portal, but some outcrops are surprisingly close to the edge, such as the kneeling camel on the north rim of the canyon. Pegmatites pegmatites is a 10 letter word starting with p and ending with s synonyms, crossword answers and other related words for pegmatites. Choose from 12 different sets of pegmatite flashcards on quizlet. Armed with this perspective, the reader should be able to better appreciate detailed reports of pegmatite occurrences such as those in brazil that are discussed elsewhere in this issue.
A look at pegmatite classifications skip simmons department. Lesson 20 gem bearing pegmatites geology and geography. Pegmatite is an intrusive igneous rock made up of large interlocking crystals. Jun 21, 2012 traditionally, most beryllium was sourced from beryl which is commonlyfound in pegmatitic environments. This was especially fitting because pegmatites are one of the most important rock types or. Pegmatite is the premier rock type for finding large high quality gemstones, and with the exception of diamond, can produce basically the whole range of the most sought after coloured gems. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. A qualitative assessment of this can be made through a simple. Pegmatites are generally associated with a parent granite in some way and can form at relatively deep to very shallow crustal levels. Pegmatite definition of pegmatite by the free dictionary. Most notably pegmatites of the nyf affiliation have required a more detailed classification as more studies revealed a greater diversity of nyftype pegmatites.
Geochemical signatures and mineralization potentials of. Chemicalgrade li refers to spodu mene that is converted to lithium carbonate or lithium hydroxide. Pegamites file introduction module b colour from the cosmos. By rakovan, john the very first word to the wise column dealt with the term pegmatite rakovan 2003. Some pegmatites contain spodumene, a mined lithium mineral. Pegmatites and aplites are a treasure box for mineralogists in terms of finding new minerals or refining the structure of rare. The most successful models for the origins and internal evolution of. Sep 19, 2017 pegmatite meaning pegmatite pronunciation pegmatite definition pegmatite explanation how to pronounce pegmatite. It is a granitic pegmatite that intrudes the boundary between two rock units in a dike that is up to two meters wide. Pegamites file introduction module b colour from the. Jun, 2018 pegmatite is an intrusive igneous rock made up of large interlocking crystals. This zonation is expressed both in cross section and map view. 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. Information on recent finds, journal articles relating to pegmatites and information about upcoming shows and conferences.
A geological, geochemical and textural study of a lct pegmatite. The missing link between granites and granitic pegmatites. Most pegmatites are composed of quartz, feldspar and mica, having a similar silicic composition as granite. Words formed from any letters in pegmatite, plus an optional blank or existing letter. In most rocks feldspar is in too small grains and is too intimately associated with other minerals to be of commercial importance. Acicular crystals and crystal aggregates of pyrolusite are found in vugs in the pegmatites of the district. The shape of pegmatite bodies range from from tabular to inverted teardropshaped and range in size from several tens of meters up to a.
Pegmatites david london, mineralogical association of. A bibliography jacobson, mark ivan colorado school of mines, geology museum, 1714 s. Pegmatites are igneous rocks with very large crystals usually, most of the crystals will be greater than 1 cm in length. A simple granite pegmatite may contain only quartz, feldspar, and mica.
756 1520 1371 308 896 70 1093 1540 1609 1435 1395 543 551 1556 129 1473 91 401 291 401 1302 910 1153 998 1164 1276 454 199 620 567 354 1338 479