Articoli di riviste: "LCT pegmatites"

1

Breiter, K., L. Ackerman, J. Ďurišova, M. Svojtka e M. Novák. "Trace element composition of quartz from different types of pegmatites: A case study from the Moldanubian Zone of the Bohemian Massif (Czech Republic)". Mineralogical Magazine 78, n. 3 (giugno 2014): 703–22. http://dx.doi.org/10.1180/minmag.2014.078.3.17.

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AbstractThe evolution of the trace-element patterns of quartz during crystallization of pegmatite melt was investigated using laser ablation inductively coupled plasma mass spectrometry. The contents of Al, B, Ba, Be, Cr, Fe, Ge, Li, Mn, P, Rb, Sn, Sr and Ti were analysed in quartz from the border, intermediate and core zones of four granitic pegmatites differing in degree of fractionation and origin. The material investigated originates from the pegmatite district of the Strážek Unit, Moldanubian Zone, Bohemian Massif, Czech Republic and includes: lepidolite LCT (Li-Cs-Ta) pegmatite from Rožná; berylcolumbite LCT pegmatite from Věžná; anatectic pegmatite from Znětínek; and intragranitic NYF (Nb-Y-F) pegmatite Vladislav from the Třebíč Pluton. The abundances of the elements analysed varied over wide intervals: <1 to 32 ppm Li, 0.5 to 6 ppm B, <1 to 10 ppm Ge, 1 to 10 ppm P, 10 to 450 ppm Al, 1 to 45 ppm Ti and <1 to 40 ppm Fe (average sample contents). Concentrations of Be, Rb, Sr, Sn, Ba, Cr and Mn are usually <1 ppm. Quartz from LCT pegmatites exhibits a distinct evolutionary trend with a decrease in Ti and an increase in Al, Li and Ge from the pegmatite border to the core. In comparison with the most fractionated rare-metal granites, pegmatitic quartz is relatively depleted in Al and Li, but strongly enriched in Ge. Quartz from simple anatectic and NYF pegmatites is poor in all trace elements with their evolution marked by a decrease in Ti and a small increase in Ge. There is little Al or Li and neither shows any systematic change with pegmatite evolution. Using the Ti-in-quartz thermobarometer, the outer zones of the Znětínek and Vladislav pegmatites crystallized at ∼670°C, whereas the border zone in the Rožná pegmatite yields a temperature near 610°C.

2

Szentpéteri, Krisztián, Kathryn Cutts, Stijn Glorie, Hugh O'Brien, Sari Lukkari, Michallik M. Radoslaw e Alan Butcher. "First in situ Lu–Hf garnet date for a lithium–caesium–tantalum (LCT) pegmatite from the Kietyönmäki Li deposit, Somero–Tammela pegmatite region, SW Finland". European Journal of Mineralogy 36, n. 3 (3 giugno 2024): 433–48. http://dx.doi.org/10.5194/ejm-36-433-2024.

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Abstract. The in situ Lu–Hf geochronology of garnet, apatite, fluorite, and carbonate minerals is a fast-developing novel analytical method. It provides an alternative technique for age dating of accessory minerals in lithium–caesium–tantalum (LCT) rare-element (RE) pegmatites where zircon is often metamict due to alteration or radiation damage. Currently most dates from Finnish LCT pegmatites are based on columbite-group minerals (CGMs), but their occurrence is restricted to mineralised zones within the pegmatites. Accessory minerals such as garnet and apatite are widespread in both mineralised and unmineralised LCT pegmatites. Lu–Hf dating of garnet and apatite provides an exceptional opportunity to better understand the geological history of these highly sought-after sources for battery and rare elements (Li, Nb, Ta, Be) that are critical for the green transition and its technology. In this paper we present the first successful in situ Lu–Hf garnet date of 1801 ± 53 Ma for an LCT pegmatite from the Kietyönmäki deposit in the Somero–Tammela pegmatite region, SW Finland. This age is consistent with previous zircon dates obtained for the region, ranging from 1815 to 1740 Ma with a weighted mean 207Pb / 206Pb age of 1786 ± 7 Ma.

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Adingra, Martial Pohn Koffi, Zié Ouattara, Tokpa Kakeu Lionel Dimitri Boya, Augustin Junior Yapo, Koffi Joseph Brou e Brice Roland Kouassi. "Petrography and Geochemical Signatures of Pegmatites from the Southeastern Part Comoé Basin (South-East Côte d'Ivoire, North Alépé)". Journal of Geography, Environment and Earth Science International 27, n. 4 (17 maggio 2023): 51–68. http://dx.doi.org/10.9734/jgeesi/2023/v27i4680.

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The pegmatitic rocks located in the south-east of Côte d'Ivoire between the Comoé basin and the Sefwi belt are the subject of this study. The geology of this region consists of gneisses, granites, microgranites, amphibolites, mylonites and metasediments. All these rocks are generally crosscut by quartz and pegmatite lodes. The petrographic studies allow us to discriminate four groups of pegmatites on the basis of mineralogy: (i) beryl-muscovite bearing pegmatite (Aboisso-Comoé), (ii) albite-tourmaline bearing pegmatite (Aboisso-Comoé), (iii) micas-tourmaline bearing pegmatite (Alosso) and (iv) muscovite-garnet bearing pegmatite (Songan forest). XRD analyzes on 4 samples revealed the presence of lepidolite (lithium ore) in the muscovite-garnet bearing pegmatite (Songan forest) and phengite in beryl-muscovite bearing pegmatite (Aboisso-Comoé). The pegmatite diffractograms of Aboisso-Comoé (beryl-muscovite bearing pegmatite) and Songan forest (muscovite-garnet bearing pegmatite) show almost same signatures and would suggest that those pegmatites come from the same source. Geochemical analyzes by portable XRF carried out on muscovite and feldspar minerals indicate that the samples from Aboisso-Comoé and Songan forest have the characteristics of Lithium-Cesium-Tantale type (LCT) pegmatites. The geochemical diagrams indicated the probable presence of beryl and spodumene type mineralization in the muscovite-garnet bearing pegmatite.

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Gonçalves, Melgarejo, Alfonso, Amores, Paniagua, Neto, Morais e Camprubí. "The Distribution of Rare Metals in the LCT Pegmatites from the Giraúl Field, Angola". Minerals 9, n. 10 (24 settembre 2019): 580. http://dx.doi.org/10.3390/min9100580.

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The Giraúl granitic pegmatite field in Angola is composed of five pegmatite types, the most evolved belong to the beryl-columbite, beryl-columbite-phosphate and spodumene types. Pegmatites are concentrically zoned with increased grain size toward a quartz core; the most evolved pegmatites have well-developed replacement units. These pegmatites are rich in Nb-Ta oxide minerals and the field has a moderate interest for critical elements such as Ta and Hf. Tourmaline, garnet and micas occur as accessory minerals. The abundance of Zr and Nb-Ta minerals increases with the evolution of the pegmatites, as well as the proportions of beryl and Li-rich minerals. The Ta/(Ta + Nb) ratio in Nb-Ta oxide minerals and the Hf/(Hf + Zr) ratio in zircon also increase with the evolution of the pegmatites and within each pegmatite body from border to inner zones, and especially in the late veins and subsolidus replacements. Textural patterns and occurrence of late veins with Ta-rich minerals suggest that Nb and especially Ta can be enriched in late hydrothermal fluids exsolved from the magma, along with Hf and other incompatible elements as Sn, U, Pb, Sb and Bi.

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Steiner, Benedikt. "Tools and Workflows for Grassroots Li–Cs–Ta (LCT) Pegmatite Exploration". Minerals 9, n. 8 (20 agosto 2019): 499. http://dx.doi.org/10.3390/min9080499.

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The increasing demand for green technology and battery metals necessitates a review of geological exploration techniques for Li–Cs–Ta (LCT) pegmatites, which is applicable to the work of mining companies. This paper reviews the main controls of LCT pegmatite genesis relevant to mineral exploration programs and presents a workflow of grassroots exploration techniques, supported by examples from central Europe and Africa. Geological exploration commonly begins with information gathering, desktop studies and Geographic Information System (GIS) data reviews. Following the identification of prospective regional areas, initial targets are verified in the field by geological mapping and geochemical sampling. Detailed mineralogical analysis and geochemical sampling of rock, soil and stream sediments represent the most important tools for providing vectors to LCT pegmatites, since the interpretation of mineralogical phases, deportment and liberation characteristics along with geochemical K/Rb, Nb/Ta and Zr/Hf metallogenic markers can detect highly evolved rocks enriched in incompatible elements of economic interest. The importance of JORC (Joint Ore Reserves Committee) 2012 guidelines with regards to obtaining geological, mineralogical and drilling data is discussed and contextualised, with the requirement of treating LCT pegmatites as industrial mineral deposits.

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Feng, Yonggang, Ting Liang, Xiuqing Yang, Ze Zhang e Yiqian Wang. "Chemical Evolution of Nb-Ta Oxides and Cassiterite in Phosphorus-Rich Albite-Spodumene Pegmatites in the Kangxiwa–Dahongliutan Pegmatite Field, Western Kunlun Orogen, China". Minerals 9, n. 3 (8 marzo 2019): 166. http://dx.doi.org/10.3390/min9030166.

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The Kangxiwa–Dahongliutan pegmatite field in the Western Kunlun Orogen, China contains numerous granitic pegmatites around a large granitic pluton (the Dahongliutan Granite with an age of ca. 220 to 217 Ma), mainly including barren garnet-, tourmaline-bearing pegmatites, Be-rich beryl-muscovite pegmatites, and Li-, P-rich albite-spodumene pegmatites. The textures, major element contents, and trace element concentrations of columbite-group minerals (CGM) and cassiterite from three albite-spodumene pegmatites in the region were investigated using a combination of optical microscopy, SEM, EPMA and LA-ICP-MS. The CGM can be broadly classified into four types: (1) inclusions in cassiterite; (2) euhedral to subhedral crystals (commonly exhibiting oscillatory and/or sector zoning and coexisting with magmatic cassiterite); (3) anhedral aggregates; (4) tantalite-(Fe)-ferrowodginite (FeSnTa2O8) intergrowths. The compositional variations of CGM and cassiterite are investigated on the mineral scale, in individual pegmatites and within the pegmatite group. The evolution of the pegmatites is also discussed. The variation of Nb/Ta and Zr/Hf ratios of the cassiterite mimics the Nb-Ta and Zr-Hf fractionation trends in many LCT pegmatites, indicating that these two ratios of cassiterite may bear meanings regarding the pegmatite evolution.

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Grew, Edward S. "The Minerals of Lithium". Elements 16, n. 4 (1 agosto 2020): 235–40. http://dx.doi.org/10.2138/gselements.16.4.235.

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Lithium is rare in the cosmos, but the formation of continental crust has concentrated lithium into economic deposits. The 124 recognized Li mineral species occur largely in four geologic environments: (1) lithium–cesium–tantalum (LCT) granitic pegmatites and associated metasomatic rocks; (2) highly peralkaline pegmatites; (3) metasomatic rocks not directly associated with pegmatites; (4) manganese deposits. The geologically oldest Li minerals are reported from LCT pegmatites and date to 3,000–3,100 Ma, a critical period in the evolution of the continental crust and the rate of its generation. This suggests a link between the earliest appearance of LCT-family pegmatites and the onset of plate tectonics, consistent with the correlation between the observed abundance of LCT-family pegmatites and supercontinent assembly.

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Wise, Michael A., Russell S. Harmon, Adam Curry, Morgan Jennings, Zach Grimac e Daria Khashchevskaya. "Handheld LIBS for Li Exploration: An Example from the Carolina Tin-Spodumene Belt, USA". Minerals 12, n. 1 (9 gennaio 2022): 77. http://dx.doi.org/10.3390/min12010077.

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Laser-induced breakdown spectroscopy (LIBS), which has recently emerged as tool for geochemical analysis outside the traditional laboratory setting, is an ideal tool for Li exploration because it is the only technique that can measure Li in minerals, rocks, soils, and brines in-situ in the field. In addition to being used in many products essential to modern life, Li is a necessary element for a reduced carbon future and Li–Cs–Ta (LCT) granitic pegmatites are an important source of Li. Such pegmatites can have varying degrees of enrichment in Li, Rb, Cs, Be, Sn, Ga, Ta>Nb, B, P, and F. We focus here on the LCT pegmatites of the Carolina Tin-Spodumene Belt (CTSB) situated in the Kings Mountain Shear Zone, which extends from South Carolina into North Carolina. The CTSB hosts both barren and fertile pegmatites, with Li-enriched pegmatites containing spodumene, K-feldspar, albite, quartz, muscovite, and beryl. We illustrate how handheld LIBS analysis can be used for real-time Li analysis in the field at a historically important CTSB pegmatite locality in Gaston County, N.C. in four contexts: (i) elemental detection and identification; (ii) microchemical mapping; (iii) depth profiling; and (iv) elemental quantitative analysis. Finally, as an example of a practical exploration application, we describe how handheld LIBS can be used to measure K/Rb ratios and Li contents of muscovite and rapidly determine the degree of pegmatite fractionation. This study demonstrates the potential of handheld LIBS to drastically reduce the time necessary to acquire geochemical data relevant to acquiring compositional information for pegmatites during a Li pegmatite exploration program.

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Sardi, Fernando Guillermo, Márcia Elisa Boscato Gomes e Silvana Elizabeth Marangone. "Garnet composition from the Reflejos de Mar LCT-pegmatite, Ancasti district, Argentina and its implication for exploration of primary deposits of lithium". Andean Geology 50, n. 1 (31 gennaio 2023): 150. http://dx.doi.org/10.5027/andgeov50n1-3468.

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The Reflejos de Mar Li-pegmatite, located in northwestern Argentina, is part of the Villismán pegmatite group, Ancasti District, Pampean Pegmatite Province. Four garnet crystals from the outermost part of the pegmatite were analyzed by major and minor elements (SiO2, TiO2, Al2O3, Cr2O3, MgO, CaO, MnO, FeO) using electron microprobe. The pegmatite belongs to the rare-element class, spodumene type, LCT (Li-Cs-Ta) petrogenetic family. Based on their Mn and Fe contents, the analyzed garnet can be assigned to the spessartine-almandine serie. The cores and rims of the analyzed garnets show significant differences for the divalent components in VIII-coordination, especially, Mn and Fe. The average MnO and FeO contents in the cores of the grains is 34.6 and 8.29 wt%, respectively, while in the rims is 29.31 and 12.95 wt%, respectively. The Fe/Mn ratio at the core of the grains is 0.24 while at the rims it is 0.44. Cr2O3 and TiO2 contents are very low (˂0.17 wt%) and the values of SiO2 and Al2O3 are ~36 and ~21 wt%, respectively. The mean chemical and molecular formulas of the core can be expressed: [(Mn2.40 Fe0.57 Ca0.02 Mg0.02)3.01 (Al1.99 Cr0.002)2.00 (Si2.99 Ti0.01)3.00 O12]; {Sps79.8 Alm18.9 Grs0.7 Prp0.5}; and the rim as: [(Mn2.04 Fe0.89 Ca0.05 Mg0.04)3.02 (Al2.00 Cr0.002)2.00 (Si2.98 Ti0.005)3.00 O12]; {Sps67.6 Alm29.5 Grs1.6 Prp1.3}. The chemical composition of garnet from the Reflejos de Mar pegmatite is similar to other worldwide examples in similar rocks, especially LCT pegmatites, which are highly evolved and associated with Li mineralization. Therefore, its composition could be used as an additional tool in the exploration of Li-bearing pegmatites in the Pampean Pegmatite Province. The differences in Fe-Mn contents between core and rim of the crystals would be controlled by variations in composition of the pegmatitic melt and, in addition, by the simultaneous precipitation of other mineral phases, for example, schorl and Mn-Fe-bearing phosphates.

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Wise, Michael A., Adam C. Curry e Russell S. Harmon. "Reevaluation of the K/Rb-Li Systematics in Muscovite as a Potential Exploration Tool for Identifying Li Mineralization in Granitic Pegmatites". Minerals 14, n. 1 (22 gennaio 2024): 117. http://dx.doi.org/10.3390/min14010117.

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A dataset of >1190 published compositional analyses of muscovite from granitic pegmatites of varying mineralogical types was compiled to reevaluate the usefulness of K-Rb-Li systematics of muscovite as a tool for distinguishing mineralogically simple pegmatites from pegmatites with potential Li mineralization. Muscovite from (i) common, (ii) (Be-Nb-Ta-P)-enriched, (iii) Li-enriched, and (iv) REE- to F-enriched pegmatites contain Li contents that vary between 10 and 20,000 ppm depending on the degree of pegmatite fractionation. Common pegmatites are characterized by low degrees of fractionation as exhibited by K/Rb ratios ranging from 618 and 25 and Li contents generally being <200 ppm but infrequently as high as 743 ppm in muscovite. Moderately fractionated pegmatites with Be, Nb, Ta, and P enrichment contain muscovite having K/Rb ratios mostly between 45 and 7 plus Li contents between 5 to >1700 ppm. Muscovite from moderately to highly fractionated Li-rich pegmatites exhibit a wide range of K/Rb ratios and Li values: (i) K/Rb = 84 to 1.4 and Li = 35 to >18,100 ppm for spodumene pegmatites, (ii) K/Rb = 139 to 2 and Li = 139 to >18,500 ppm for petalite pegmatites, and (iii) K/Rb = 55 to 1.5 and Li = 743 to >17,800 ppm for lepidolite pegmatites. Pegmatites that host substantial REE- and F-rich minerals may carry muscovite with K/Rb ratios between 691 to 4 that has Li contents between 19 to 15,690 ppm. The K/Rb-Li behavior of muscovite can be useful in assessing the potential for Li mineralization in certain granitic pegmatite types. The proposed limits of K/Rb values and Li concentrations for identifying spodumene- or petalite-bearing pegmatites as part of an exploration program is reliable for Group 1 (LCT) pegmatite populations derived from S-type parental granites or anatectic melting of peraluminous metasedimentary rocks. However, it is not recommended for application to Group 2 (NYF) pegmatites affiliated with anorogenic to post-orogenic granitoids with A-type geochemical signatures or that derived by the anatexis of mafic rocks that generated REE- and F-rich melts.

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Galliski, Miguel Ángel, María Florencia Márquez-Zavalía, Encarnación Roda-Robles e Albrecht von Quadt. "The Li-Bearing Pegmatites from the Pampean Pegmatite Province, Argentina: Metallogenesis and Resources". Minerals 12, n. 7 (30 giugno 2022): 841. http://dx.doi.org/10.3390/min12070841.

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The Li-bearing pegmatites of the Pampean Pegmatite Province (PPP) occur in a rare-element pegmatite belt developed mainly in the Lower Paleozoic age on the southwestern margin of Gondwana. The pegmatites show Li, Rb, Nb ≤ Ta, Be, P, B, Bi enrichment, and belong to the Li-Cs-Ta (LCT) petrogenetic family, Rare-Element-Li (REL-Li) subclass; most of them are of complex type and spodumene subtype, some are of albite-spodumene type, and a few of petalite subtype. The origin of the pegmatites is attributed predominantly to fractionation of fertile S-type granitic melts produced by either fluid-absent or fluid-assisted anatexis of a thick pile of Gondwana-derived turbiditic sediments. Most of the pegmatites are orogenic (530–440 Ma) and developed during two overlapped collisional orogenies (Pampean and Famatinian); a few are postorogenic (~370 Ma), related to crustal contaminated A-type granites. The pegmatites were likely intruded in the hinterland, preferably in medium-grade metamorphic rocks with PT conditions ~200–500 MPa and 400–650 °C, where they are concentrated in districts and groups. Known combined resources add up 200,000 t of spodumene, with variable grades between 5 and 8 wt.% Li2O. The potential for future findings and enlargement of the resources is high, since no systematic exploration program has yet been developed.

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Cardoso-Fernandes, Joana, Douglas Santos, Cátia Rodrigues de Almeida, Julia Tucker Vasques, Ariane Mendes, Ricardo Ribeiro, Antonio Azzalini et al. "The INOVMineral Project’s Contribution to Mineral Exploration—A WebGIS Integration and Visualization of Spectral and Geophysical Properties of the Aldeia LCT Pegmatite Spodumene Deposit". Minerals 13, n. 7 (19 luglio 2023): 961. http://dx.doi.org/10.3390/min13070961.

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Due to the current energetic transition, new geological exploration technologies are needed to discover mineral deposits containing critical materials such as lithium (Li). The vast majority of European Li deposits are related to Li–Cs–Ta (LCT) pegmatites. A review of the literature indicates that conventional exploration campaigns are dominated by geochemical surveys and related exploration tools. However, other exploration techniques must be evaluated, namely, remote sensing (RS) and geophysics. This work presents the results of the INOVMINERAL4.0 project obtained through alternative approaches to traditional geochemistry that were gathered and integrated into a webGIS application. The specific objectives were to: (i) assess the potential of high-resolution elevation data; (ii) evaluate geophysical methods, particularly radiometry; (iii) establish a methodology for spectral data acquisition and build a spectral library; (iv) compare obtained spectra with Landsat 9 data for pegmatite identification; and (v) implement a user-friendly webGIS platform for data integration and visualization. Radiometric data acquisition using geophysical techniques effectively discriminated pegmatites from host rocks. The developed spectral library provides valuable insights for space-based exploration. Landsat 9 data accurately identified known LCT pegmatite targets compared with Landsat 8. The user-friendly webGIS platform facilitates data integration, visualization, and sharing, supporting potential users in similar exploration approaches.

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Santos, Douglas, Joana Cardoso-Fernandes, Alexandre Lima, Axel Müller, Marco Brönner e Ana Cláudia Teodoro. "Spectral Analysis to Improve Inputs to Random Forest and other Boosted Ensemble Tree-Based Algorithms for Detecting NYF Pegmatites in Tysfjord, Norway". Remote Sensing 14, n. 15 (23 luglio 2022): 3532. http://dx.doi.org/10.3390/rs14153532.

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As an important source of lithium and rare earth elements (REE) and other critical elements, pegmatites are of great strategic economic interest for present and future technological development. Identifying new pegmatite deposits is a strategy adopted by the European Union (EU) to decrease its import dependence on non-European countries for these raw materials. It is in this context that the GREENPEG project was established, an EU project whose main objective is to identify new deposits of pegmatites in Europe in an environmentally friendly way. Remote sensing is a non-contact exploration tool that allows for identifying areas of interest for exploration at the early stage of exploration campaigns. Several RS methods have been developed to identify Li-Cs-Ta (LCT) pegmatites, but in this study, a new methodology was developed to detect Nb-Y-F (NYF) pegmatites in the Tysfjord area in Norway. This methodology is based on spectral analysis to select bands of the Sentinel 2 satellite and adapt RS methods, such as Band Ratios and Principal Component Analysis (PCA), to be used as input in the Random Forest (RF) and other tree-based ensemble algorithms to improve the classification accuracy. The results obtained are encouraging, and the algorithm was able to successfully identify the pegmatite areas already known and new locations of interest for exploration were also defined.

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Cardoso-Fernandes, Joana, Douglas Santos, Cátia Rodrigues de Almeida, Alexandre Lima e Ana C. Teodoro. "Spectral Library of European Pegmatites, Pegmatite Minerals and Pegmatite Host-Rocks – the GREENPEG project database". Earth System Science Data 15, n. 7 (20 luglio 2023): 3111–29. http://dx.doi.org/10.5194/essd-15-3111-2023.

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Abstract. The New Exploration Tools for European Pegmatite Green-Tech Resources (GREENPEG) spectral database contains the spectral signature, obtained through reflectance spectroscopy studies, of European pegmatites and minerals as well as their host rocks. Samples include pegmatites of the Nb–Y–F (NYF) and Li–Cs–Ta (LCT) chemical types and host rocks from pegmatite locations in Austria, Ireland, Norway, Portugal, and Spain. The database contains the reflectance spectra (raw and continuum-removed spectra), sample photographs, and main absorption features automatically extracted by a self-proposed Python routine. Whenever possible, spectral mineralogy was interpreted based on the continuum-removed spectra. A detailed description of the database, its content and structure, the measuring instrument, and interoperability with geographic information system (GIS) tools is available in this database report. Moreover, examples of how the data can be used and interpreted are also provided. The advantages and added value of the presented dataset reside in its European scale, with representative samples from pegmatites with distinct genesis, mineralogy, structure, and host rocks that can be used as a reference for pegmatite exploration at a global scale via, for example, satellite image processing. The reported spectral mineral assemblages can also be of interest when considering resource estimation or ore processing. Thus, it is expected that this open dataset, available on the Zenodo platform https://doi.org/10.5281/zenodo.6518318 (Cardoso-Fernandes et al., 2022b), will be a reference for distinct types of users, ranging from academia to industry.

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BUYSE, Florian, Stijn DEWAELE, Matthieu N. BOONE e Veerle CNUDDE. "Contribution of 3D automated mineralogy in unraveling the formation history of Nb-Ta-Sn mineralized LCT pegmatites in the Karagwe-Ankole belt (Central Africa)". Geologica Belgica 27, n. 1-2 (30 giugno 2024): 1–14. http://dx.doi.org/10.20341/gb.2024.001.

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The Mesoproterozoic Karagwe-Ankole belt (KAB) in Central Africa hosts important mineralized lithium-cesium-tantalum pegmatites enriched in Sn, Nb, Ta and W. Microscopic techniques are required to further refine the paragenetic history of mineralized pegmatites in the KAB and to understand the pegmatite-forming processes leading to an enrichment of economically important minerals. Using a combination of scanning electron microscopy (SEM)-based automated mineralogy systems with X-ray computed tomography (µCT), we investigated the mineral relationships in a three-dimensional (3D) space. This paper presents new insights into the crystallization sequence of mineralized pegmatites in the KAB. A stage of albitization followed the primary crystallization, where muscovite probably plays a role in the fluid migration and the subsequent precipitation of ore minerals. Primary saccharoidal albitization was followed by tourmaline crystallization, but before the secondary cleavelandite-type albitization. The ‘Cornish Type’ cassiterite originating from greisen pockets confirms the suggested hydrothermal formation conditions. A first-time description of oriented zircon and the association with flat tabular columbite-tantalite points to the importance of local magmatic-hydrothermal conditions. This study emphasizes the possibilities of using 3D automated mineralogy for the identification of minerals and their position in the paragenetic history of mineralized pegmatites and by extension of microscopically complex and diverse ore deposits.

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Montenegro, Teresita, Julieta Wul, Mónica López de Luchi, Enrico Ribacki e Robert B. Trumbull. "Chemical and boron isotope composition of tourmaline from pegmatites and their host rocks, Sierra de San Luis, Argentina". Canadian Mineralogist 59, n. 3 (1 maggio 2021): 467–94. http://dx.doi.org/10.3749/canmin.2000072.

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ABSTRACT We report chemical and B-isotope analyses of tourmaline from Ordovician S-type granites, an aplite, LCT-type (lithium-cesium-tantalum) pegmatites, and metamorphic rocks of the Conlara Metamorphic Complex (CMC) in Sierra de San Luis, Argentina. For comparison, tourmaline from three LCT pegmatites in the adjacent Pringles Metamorphic Complex was also studied. Metamorphic tourmaline from the CMC has intermediate schorl–dravite compositions, with variable Fe# [100 * Fe/(Fe + Mg)] from 32 to 79. The δ11B values range from –14.8 to –8.9‰, which are typical values for continental metasediments and granites, ruling out a marine origin for the tourmalinite protoliths. Tourmaline from the S-type granites and aplite is more homogeneous, with Fe# from 48 to 60. The δ11B range (–14 to –9.8‰) of granitic tourmaline is within that of the metamorphic tourmaline, supporting the idea of boron recycling in the CMC during partial melting to form the granites. Tourmaline from CMC-hosted pegmatites is compositionally diverse and we distinguished three groups based on Fe#: Group 1: 42 to 50, Group 2: 50 to 62, and Group 3: 62 to 93. Regardless of strong variations in Fe#, tourmaline from all pegmatites in the CMC has δ11B values from –10.3 to –7.8‰. These values overlap with the range of related granites but are about 2 permil higher, which we attribute to crystallization of 10B-enriched minerals (mica and tourmaline) in the evolved magma from which the pegmatites formed. Pegmatites from the Pringles Metamorphic Complex contain tourmaline with a similar overall range of Fe# (45 to 84) as in the CMC but lower δ11B values (–13.2 to –11.2‰).

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Graupner, T., F. Melcher, H. E. Gäbler, M. Sitnikova, H. Brätz e A. Bahr. "Rare earth element geochemistry of columbite-group minerals: LA-ICP-MS data". Mineralogical Magazine 74, n. 4 (agosto 2010): 691–713. http://dx.doi.org/10.1180/minmag.2010.074.4.691.

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AbstractNew data on rare earth element (REE) concentrations and distribution patterns of columbite-tantalite minerals from Ta-ore provinces worldwide are presented. The REE geochemistry was studied by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Five major types of chondrite-normalized REE distribution patterns are defined for columbite-group minerals (CGM) from lithium-caesium-tantalum (LCT) pegmatites and rare-metal granites. Features to discriminate between the types include (1) the shape of the pattern (e.g. flat or concave), (2) calculated ratios between groups of the REE (e.g. heavy REEN/middle REEN), and (3) the presence and intensity of anomalies (e.g. Ce*, Eu*). Four pegmatites in central and southern Africa are used as case studies to discuss application of the types of REE patterns in individual deposits. The REE fractionation during progressive evolution of the melt in a pegmatite body (either Nb → Ta or Fe → Mn fractionation lines, or both) results in smaller heavy REEN/middle REEN ratios whereas replacement of primary CGM by secondary CGM produces modifications in the light REEN patterns and the heavy REEN/middle REEN ratios also. Critical features of REE patterns such as highly variable heavy REEN/middle REEN ratios or striking differences in the appearance of Eu anomalies are discussed considering structural data of the host minerals and the differentiation behaviour of the pegmatitic melt. In general, CGM from each individual Ta-ore province are characterized by a predominance of one type of REE distribution pattern. Consequently, these patterns are suitable for tracing the origin of tantalum ore concentrates (e.g. as a forensic tool).

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López de Azarevich, Vanina, Paolo Fulignati, Anna Gioncada e Miguel Azarevich. "Rare element minerals’ assemblage in El Quemado pegmatites (Argentina): insights for pegmatite melt evolution from gahnite, columbite-group minerals and tourmaline chemistry and implications for minerogenesis". Mineralogy and Petrology 115, n. 5 (19 maggio 2021): 497–518. http://dx.doi.org/10.1007/s00710-021-00752-0.

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AbstractThe pegmatite district of El Quemado (NW Pampean Ranges, NW Argentina) hosts several Ordovician pegmatite bodies of the LCT (Li, Cs, Ta) type. We present paragenetic assemblages for a set of samples from two of the El Quemado pegmatite groups, Santa Elena and Tres Tetas, and mineral chemistry analyses for gahnite, columbite-group minerals, tourmaline, micas, albite, microcline, and discuss the relation between their major element composition and the degree of evolution of pegmatite melts. The chemical composition of rare element minerals allows recognizing an evolutive trend reaching highly differentiated compositions, with complex paragenetic assemblages including Li-, Zr-, U-, Zn-, P-, Mn- and Ta-bearing minerals. The temperature of crystallization during the magmatic phase was below 400 °C. Non-pervasive hydrothermal alteration, testified by a moderate presence of phyllosilicates, affected the pegmatite bodies. Chlorite geothermometry indicates that the circulation of post-magmatic hydrothermal fluids occurred at a temperature ranging between 200 °C and 250 °C. The mineralogical features recognized in the El Quemado pegmatite rocks have implications for the metallogenesis of the region, suggesting that the pegmatites potentially contributed to the genesis of Ta-Nb oxide placer mineralizations.

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Szuszkiewicz, Adam, Adam Pieczka, Bożena Gołębiowska, Magdalena Dumańska-Słowik, Mariola Marszałek e Eligiusz Szełęg. "Chemical Composition of Mn- and Cl-Rich Apatites from the Szklary Pegmatite, Central Sudetes, SW Poland: Taxonomic and Genetic Implications". Minerals 8, n. 8 (14 agosto 2018): 350. http://dx.doi.org/10.3390/min8080350.

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Although calcium phosphates of the apatite group (apatites) with elevated contents of Mn are common accessory minerals in geochemically evolved granitic pegmatites, their Mn-dominant analogues are poorly studied. Pieczkaite, M1Mn2M2Mn3(PO4)3XCl, is an exceptionally rare Mn analogue of chlorapatite known so far from only two occurrences in the world, i.e., granitic pegmatites at Cross Lake, Manitoba, Canada and Szklary, Sudetes, SW Poland. In this study, we present the data on the compositional variation and microtextural relationships of various apatites highly enriched in Mn and Cl from Szklary, with the main focus on compositions approaching or attaining the stoichiometry of pieczkaite (pieczkaite-like apatites). The main goal of this study is to analyze their taxonomical position as well as discuss a possible mode of origin. The results show that pieczkaite-like apatites represent the Mn-rich sector of the solid solution M1(Mn,Ca)2M2(Mn,Ca)3(PO4)3X(Cl,OH). In the case of cation-disordered structure, all these compositions represent extremely Mn-rich hydroxylapatite or pieczkaite. However, for cation-ordered structure, there are also intermediate compositions for which the existence of two hypothetical end-member species can be postulated: M1Ca2M2Mn3(PO4)3XCl and M1Mn2M2Ca3(PO4)3XOH. In contrast to hydroxylapatite and pieczkaite, that are members of the apatite-group, the two hypothetical species would classify into the hedyphane group within the apatite supergroup. The pieczkaite-like apatites are followed by highly Mn-enriched fluor- and hydroxylapatites in the crystallization sequence. Mn-poor chlorapatites, on the other hand, document local contamination by the serpentinite wall rocks. We propose that pieczkaite-like apatites in the Szklary pegmatite formed from small-volume droplets of P-rich melt that unmixed from the LCT-type (Li–Cs–Ta) pegmatite-forming melt with high degree of Mn-Fe fractionation. The LCT melt became locally enriched in Cl through in situ contamination by wall rock serpentinites.

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Leal Gomes, Carlos A. A., e Ana M. R. Neiva. "Tourmalines in the Namacotche Li-Cs-Ta granitic pegmatite group, Mozambique: crystal chemistry and origin". Cadernos do Laboratorio Xeolóxico de Laxe. Revista de Xeoloxía Galega e do Hercínico Peninsular 44 (29 dicembre 2022): 132–53. http://dx.doi.org/10.17979/cadlaxe.2022.44.0.9291.

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The field work, backscattered electron images and detailed microanalyses of three generations of tourmaline from the Namacotche LCT pegmatites allows de distinction between the compositional magmatic and hydrothermal tourmalines. The generation 1 occurs in the outer intermediate zone of the pegmatite. It consists of zoned crystals with an oscillatory inner core of foitite and schorl, an outer core of schorl and an Fe-rich fluor-elbaite rim. Unzoned Fe-rich fluor-elbaite crystals occur in the inner intermediate zone of the pegmatite. All the crystals are derived by fractionation of a (Al, Li, B)-rich pegmatite melt. However, the rim of zoned crystals and some compositions of unzoned crystals show evidence of hydrothermal fluids, as they plot outside the fractionation trends. The zoned fluor-elbaite crystals of the generation 2 are from the inner intermediate zone of the pegmatite. They have a pink core and a green rim. The rim has higher YFe2+, Na, F contents YFe2+/(YFe2++Licalc.) value and lower Si, YAl, Licalc. and X-site vacancy contents, X-vacancy/(Na+X-vacancy) value than the core. Both zones are hydrothermal. The rim is an overgrowth. The fluor-elbaite gemmy crystals of the generation 3 occur in sheared breccia blasts and clasts with a cookeite matrix. They depend mainly on the fluid-rich hydrothermal environment of low temperatures (280-150ºC). Some from the cycle a may result from the dissolution of magmatic tourmaline crystals of the generation 1 from the sheared outer and inner intermediate zones of the pegmatite due to reaction with late fluids in chemical disequilibrium, followed by growth of tourmaline with low temperature hydrothermal fluids. The evolution from the cycle a to the cycle b and to the cycle c of the generation 3 implies that the hydrothermal reacting fluids were undergoing fractionation and becoming richer in Li and poorer in Fe2+ during the late hydrothermal crystallization of the pegmatites.

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Huber, Miłosz, Daniel M. Kamiński e Urszula Maciołek. "The Optical and Spectroscopic Properties of Fuchsite, Spodumene, and Lepidolite from Northern Scandinavia (Kautokeino, Kaustinen, Kolmozero)". Materials 16, n. 14 (8 luglio 2023): 4894. http://dx.doi.org/10.3390/ma16144894.

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Li-Ce-Ta (LCT) pegmatites containing lithium mineralization in the form of spodumene and lepidolite, as well as fuchsite, from the regions of northern Scandinavia (N Norway, N Finland, N Russia) were studied. Detailed analyses of the chemical compositions of these minerals were carried out, involving scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy with attenuated total reflectance (ATR), and X-ray photoelectron spectroscopy (XPS) studies. Their crystal structures were confirmed with the X-ray diffraction technique. Studies involving microscopy were also carried out, indicating the optical features of these minerals. Based on the analyses carried out in the studied rocks, the characteristics of these minerals were determined, as well as the crystallization conditions. This research indicates that the N Scandinavian area is prospective and may lead to further discoveries of this type of pegmatite in the studied region.

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Goodenough, Kathryn M., Richard A. Shaw, Martin Smith, Guillaume Estrade, Eva Marqu, Cyrielle Bernard e Paul Nex. "Economic mineralization in pegmatites: comparing and contrasting NYF and LCT examples". Canadian Mineralogist 57, n. 5 (30 settembre 2019): 753–55. http://dx.doi.org/10.3749/canmin.ab00013.

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Huber, Miłosz, Daniel Kamiński e Urszula Maciołek. "Columbite–Tantalite from Northern Scandinavia (Kaustinen, Kolmozero) Pegmatites: An Optical and Spectroscopic Properties". Crystals 13, n. 4 (3 aprile 2023): 612. http://dx.doi.org/10.3390/cryst13040612.

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LCT (lithium–cesium–tantalum) pegmatites from the Kaustinen and Kolmozero regions contain columbite–tantalite mineralization, which has been presented in this study. Crystal structure, Raman microscopy, and optical property analyses of these minerals were performed. As a result of the structural studies and micro-area analyses, it was determined that these minerals in the pegmatites in question constitute a solid solution with numerous Mn-Fe and Nb-Ta substitutions within a single crystal. The ratio between Mn-Fe and Nb-Ta can change from crystal to crystal, which makes it impossible to find precise stechiometry between these ions. The crystallization conditions of these minerals were also determined by studying the associations of other rock-forming minerals and accessory minerals in the discussed rocks.

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Defnet, Peter A., Michael A. Wise, Russell S. Harmon, Richard R. Hark e Keith Hilferding. "Analysis of Garnet by Laser-Induced Breakdown Spectroscopy—Two Practical Applications". Minerals 11, n. 7 (29 giugno 2021): 705. http://dx.doi.org/10.3390/min11070705.

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Laser-induced breakdown spectroscopy (LIBS) is a simple and straightforward technique of atomic emission spectroscopy that can provide multi-element detection and quantification in any material, in-situ and in real time because all elements emit in the 200–900 nm spectral range of the LIBS optical emission. This study evaluated two practical applications of LIBS—validation of labels assigned to garnets in museum collections and discrimination of LCT (lithium-cesium-tantalum) and NYF (niobium, yttrium and fluorine) pegmatites based on garnet geochemical fingerprinting, both of which could be implemented on site in a museum or field setting with a handheld LIBS analyzer. Major element compositions were determined using electron microprobe analysis for a suite of 208 garnets from 24 countries to determine garnet type. Both commercial laboratory and handheld analyzers were then used to acquire LIBS broadband spectra that were chemometrically processed by partial least squares discriminant analysis (PLSDA) and linear support vector machine classification (SVM). High attribution success rates (>98%) were obtained using PLSDA and SVM for the handheld data suggesting that LIBS could be used in a museum setting to assign garnet type quickly and accurately. LIBS also identifies changes in garnet composition associated with increasing mineral and chemical complexity of LCT and NYF pegmatites.

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McNeil, Alysha G., Robert L. Linnen, Roberta L. Flemming e Mostafa Fayek. "An experimental approach to examine fluid-melt interaction and mineralization in rare-metal pegmatites". American Mineralogist 105, n. 7 (1 luglio 2020): 1078–87. http://dx.doi.org/10.2138/am-2020-7216.

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Abstract Niobium and tantalum, rare metals and high field strength elements (HFSEs) that are essential to modern technologies, are concentrated among others in lithium-cesium-tantalum (LCT) pegmatites and rare metal granites. The most important hosts for Nb-Ta in these types of deposits are the columbite group minerals (columbite-tantalite), but at some ore deposits significant Ta is also contained in wodginite, microlite, and tapiolite. Previous solubility experiments of HFSE minerals have been limited to high temperatures because of the slow diffusivities of HFSEs in granitic melts. An experiment protocol is described herein that allows HFSE mineral solubilities to be determined at lower temperatures, more in line with the estimated solidus temperatures of LCT pegmatites and rare metal granites. This is achieved through the interaction of a melt that is enriched in high field strength elements (e.g., P and Nb or Ta) with a fluid enriched in a fluid-mobile element (FME, e.g., Mn). A starting glass enriched in a slow diffusing HFSE was synthesized, and HFSE mineral saturation is obtained via the diffusion of a FME into the melt via interaction with a fluid. This interaction can occur at much lower temperatures in reasonable experimental durations than for experiments that require diffusion of niobium and tantalum. The solubility product of columbite-(Mn) from the fluid-melt interaction experiment in a highly fluxed granitic melt at 700 °C is the same as those from dissolution and crystallization (reversal) experiments at the same P-T conditions. Thus, both methods produce reliable measurements of mineral solubility, and the differences in the metal concentrations in the quenched melts indicates that the solubility of columbite-(Mn) follows Henry's Law. Results show that columbite-(Mn) saturation can be reached at geologically reasonable concentrations of niobium in melts and manganese in hydrothermal fluids. This experimental protocol also allows the investigation of HFSE mineral crystallization by fluid-melt interactions in rare-metal pegmatites. Magmatic origins for columbite group minerals are well constrained, but hydrothermal Nb-Ta mineralization has also been proposed for pegmatite-hosted deposits such as Tanco, Greenbushes, and granite-hosted deposits such as Cínovec/Zinnwald, Dajishan, and Yichun. This study shows that columbite-(Mn), lithiophilite, and a Ca-Ta oxide mineral (that is likely microlite) crystallized from experiments in fluid-melt systems at temperatures as low as 650 °C at 200 MPa. It is important to note that HFSE minerals that crystallize from fluid-melt interactions texturally occur as euhedral crystals as phenocrysts in glass, i.e., are purely magmatic textures. Therefore, crystallization of HFSE minerals from fluid-melt interactions in rare metal granites and pegmatite deposits may be more widespread than previously recognized. This is significant because the formation of these deposits may require magmatic-hydrothermal interaction to explain the textures present in deposits worldwide, rather than always being the result of a single melt or fluid phase.

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Diella, Valeria, Federico Pezzotta, Rosangela Bocchio, Nicoletta Marinoni, Fernando Cámara, Antonio Langone, Ilaria Adamo e Gabriele Lanzafame. "Gem-Quality Tourmaline from LCT Pegmatite in Adamello Massif, Central Southern Alps, Italy: An Investigation of Its Mineralogy, Crystallography and 3D Inclusions". Minerals 8, n. 12 (13 dicembre 2018): 593. http://dx.doi.org/10.3390/min8120593.

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In the early 2000s, an exceptional discovery of gem-quality multi-coloured tourmalines, hosted in Litium-Cesium-Tantalum (LCT) pegmatites, was made in the Adamello Massif, Italy. Gem-quality tourmalines had never been found before in the Alps, and this new pegmatitic deposit is of particular interest and worthy of a detailed characterization. We studied a suite of faceted samples by classical gemmological methods, and fragments were studied with Synchrotron X-ray computed micro-tomography, which evidenced the occurrence of inclusions, cracks and voids. Electron Microprobe combined with Laser Ablation analyses were performed to determine major, minor and trace element contents. Selected samples were analysed by single crystal X-ray diffraction method. The specimens range in colour from colourless to yellow, pink, orange, light blue, green, amber, brownish-pink, purple and black. Chemically, the tourmalines range from fluor-elbaite to fluor-liddicoatite and rossmanite: these chemical changes occur in the same sample and affect the colour. Rare Earth Elements (REE) vary from 30 to 130 ppm with steep Light Rare Earth Elemts (LREE)-enriched patterns and a negative Eu-anomaly. Structural data confirmed the elbaitic composition and showed that high manganese content may induce the local static disorder at the O(1) anion site, coordinating the Y cation sites occupied, on average, by Li, Al and Mn2+ in equal proportions, confirming previous findings. In addition to the gemmological value, the crystal-chemical studies of tourmalines are unanimously considered to be a sensitive recorder of the geological processes leading to their formation, and therefore, this study may contribute to understanding the evolution of the pegmatites related to the intrusion of the Adamello pluton.

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Daneshvar, Narges, Hossein Azizi, Yoshihiro Asahara, Motohiro Tsuboi, Masayo Minami e Yousif O. Mohammad. "Geochemistry and Genesis of Beryl Crystals in the LCT Pegmatite Type, Ebrahim-Attar Mountain, Western Iran". Minerals 11, n. 7 (2 luglio 2021): 717. http://dx.doi.org/10.3390/min11070717.

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Ebrahim-Attar granitic pegmatite, which is distributed in southwest Ghorveh, western Iran, is strongly peraluminous and contains minor beryl crystals. Pale-green to white beryl grains are crystallized in the rim and central parts of the granite body. The beryl grains are characterized by low contents of alkali oxides (Na2O = 0.24–0.41 wt.%, K2O = 0.05–0.17 wt.%, Li2O = 0.03–0.04 wt.%, and Cs2O = 0.01–0.03 wt.%) and high contents of Be2O oxide (10.0 to 11.9 wt.%). The low contents of alkali elements (oxides), low Na/Li (apfu) ratios (2.94 to 5.75), and variations in iron oxide (FeO= 0.28–1.18 wt.%) reveal a poorly evolved magmatic source of the beryl grains. Low abundances of rare earth elements (ΣREE = 0.8–4.9 ppm) with high 87Sr/86Sr(i) ratios of 0.739 ±0.036 for the beryl grains and 0.7081 for the host granites infer that the primary magma was directly produced by partial melting of the upper continental crust (UCC). The crystallization temperature of the Ebrahim-Attar granitic pegmatite changes from 586 to 755 °C (average = 629 °C), as calculated based on the zircon saturation index. Furthermore, the quartz geobarometer calculation shows that crystallization occurred at pressures of approximately 233–246 MPa. This pressure range is a promising condition for saturation of Be in magma. During granitic magma crystallization, the melt was gradually saturated with Be, and then beryl crystallized in the assemblage of the main minerals such as quartz and feldspar. Likewise, the host granite is characterized by high ratios of Nb/Ta (4.79–16.3) and Zr/Hf (12.2–19.1), and peraluminous signatures are compatible with Be-bearing LCT (Li-Ce and Ta) pegmatites.

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Eagle, Ryan M., William D. Birch e Stafford McKnight. "Phosphate minerals in granitic pegmatites from the Mount Wills District, north-eastern Victoria". Proceedings of the Royal Society of Victoria 127, n. 2 (2015): 55. http://dx.doi.org/10.1071/rs15018.

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Tin- and tantalum-bearing LCT-type granitic pegmatites occur in a 45 km long belt between Eskdale and Mount Wills in north-eastern Victoria. Near Mount Wills, several compositionally zoned rare-element pegmatites contain complex assemblages of primary and secondary phosphate minerals, many of which are rare and previously unrecorded in Victoria. The phosphate assemblages can be divided into Al-rich and Fe–Mn-rich suites, in addition to ubiquitous fluorapatite. The Al-rich phosphate suite includes montebrasite, scorzalite, bertossaite and brazilianite. The Fe‒Mn phosphate suite includes heterosite, phosphoferrite, wolfeite, alluaudite (sp.), arrojadite (sp.) and jahnsite (sp.), derived from the metasomatic alteration of primary triplite. Further hydrothermal alteration of this assemblage has resulted in a secondary suite of strengite, rockbridgeite, phosphosiderite, whiteite, jahnsite and whitmoreite forming in etch cavities and fractures. A Late Silurian age of 420±4 Ma was obtained from one of the dykes via CHIME radiometric dating of monazite, suggesting a similar age for the adjacent Mount Wills Granite, which has not been reliably dated. This highly fractionated, peraluminous granite is presumed to be the source of the rare-element pegmatites based on their close spatial relationship.

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Eagle, Ryan M., William D. Birch e Stafford McKnight. "Corrigendum to: Phosphate minerals in granitic pegmatites from the Mount Wills District, north-eastern Victoria". Proceedings of the Royal Society of Victoria 129, n. 1 (2017): 53. http://dx.doi.org/10.1071/rs15018_co.

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Tin- and tantalum-bearing LCT-type granitic pegmatites occur in a 45 km long belt between Eskdale and Mount Wills in north-eastern Victoria. Near Mount Wills, several compositionally zoned rare-element pegmatites contain complex assemblages of primary and secondary phosphate minerals, many of which are rare and previously unrecorded in Victoria. The phosphate assemblages can be divided into Al-rich and Fe–Mn-rich suites, in addition to ubiquitous fluorapatite. The Al-rich phosphate suite includes montebrasite, scorzalite, bertossaite and brazilianite. The Fe‒Mn phosphate suite includes heterosite, phosphoferrite, wolfeite, alluaudite (sp.), arrojadite (sp.) and jahnsite (sp.), derived from the metasomatic alteration of primary triplite. Further hydrothermal alteration of this assemblage has resulted in a secondary suite of strengite, rockbridgeite, phosphosiderite, whiteite, jahnsite and whitmoreite forming in etch cavities and fractures. A Late Silurian age of 420±4 Ma was obtained from one of the dykes via CHIME radiometric dating of monazite, suggesting a similar age for the adjacent Mount Wills Granite, which has not been reliably dated. This highly fractionated, peraluminous granite is presumed to be the source of the rare-element pegmatites based on their close spatial relationship.

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Deveaud, Sarah, Romain Millot e Arnaud Villaros. "The genesis of LCT-type granitic pegmatites, as illustrated by lithium isotopes in micas". Chemical Geology 411 (settembre 2015): 97–111. http://dx.doi.org/10.1016/j.chemgeo.2015.06.029.

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Choudhury, Manideepa Roy, Nikhil Agarwal e Suresh Chander. "Occurrence of Liddicoatite-Bearing LCT Pegmatites in Sirohi Region, Northwest India and their Rare Metal Potentiality". Current Science 118, n. 5 (10 marzo 2020): 809. http://dx.doi.org/10.18520/cs/v118/i5/809-818.

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Bhandari, Sushmita, Kezhang Qin, Qifeng Zhou e Noreen J. Evans. "Geological, Mineralogical and Geochemical Study of the Aquamarine-Bearing Yamrang Pegmatite, Eastern Nepal with Implications for Exploration Targeting". Minerals 12, n. 5 (30 aprile 2022): 564. http://dx.doi.org/10.3390/min12050564.

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The Yamrang Pegmatite in the Ikhabu Pegmatite Field, Eastern Nepal is Nepal's primary source of aquamarine. This paper reports detailed mineralogy and whole rock granite and pegmatite geochemistry, and major and trace element data for alkali feldspar and muscovite in order to classify the aquamarine-bearing Yamrang Pegmatite, elucidate beryl-saturation processes and evaluate potential geochemical exploration tools for beryl-pegmatites. Five internal mineralogical/textural zones were identified in the Yamrang Pegmatite; zone 1 (saccharoidal albite); zone 2 (blocky perthitic microcline); zone 3 (muscovite–microcline–quartz); zone 4 (beryl-quartz), and zone 5 (miarolitic cavities). Zones 1–4 represent the magmatic stage, while zone 5 formed during the hydrothermal stage of pegmatite genesis. Spectacular aquamarines are recovered from miarolitic zone 5, while beryl saturation is found in zones 3, 4, and 5. Based on beryllium (Be) content, Be partition among co-existing minerals at the magmatic stage is beryl > muscovite > tourmaline > alkali feldspar > quartz. In contrast, the sequence at the hydrothermal stage is beryl > muscovite > albite > tourmaline > quartz. The Be content in rock-forming minerals decreases from pegmatite margin to core, and tourmaline could have played a significant role in Be enrichment processes in the marginal pegmatite zone. High temperature, a low degree of fractionation, and the dominance of Be-compatible mineral phases such as muscovite, calcium-rich alkali feldspar and tourmaline resulted in beryl undersaturation in marginal zones. However, low temperature, high fractional crystallization, and low abundance of Be-compatible mineral phases resulted in beryl saturation in inner zones. The strongly peraluminous nature, low total REE content (<500 ppm), mineral assemblage of beryl, tourmaline, spessartine, columbite-tantalite, depletion of Ba, Nb, and enrichment of Pb, Rb, Cs in the primitive mantle normalized multi-element plots suggest that the beryl-bearing Yamrang Pegmatite corresponds to the LCT pegmatite family. Alkali feldspar with K/Rb values of 30–150, Rb ~ 3000 ppm, Cs >100 ppm, and muscovite, with K/Rb ranging 18–50, Rb ~ 6000 ppm, Cs > 500 ppm, and Ta >65 ppm in inner zones (3–5), indicate that the Yamrang Pegmatite is an intermediate-fractionated, beryl-type rare-element (REL) pegmatite. It is probable that whole rock Be content of >10 ppm could be considered an exploration guide to beryl mineralization in the region.

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Grew, Edward S., Ferdinando Bosi, Linus Ros, Per Kristiansson, Mickey E. Gunter, Ulf Hålenius, Robert B. Trumbull e Martin G. Yates. "Fluor-elbaite, lepidolite and Ta–Nb oxides from a pegmatite of the 3000 Ma Sinceni Pluton, Swaziland: evidence for lithium–cesium–tantalum (LCT) pegmatites in the Mesoarchean". European Journal of Mineralogy 30, n. 2 (20 agosto 2018): 205–18. http://dx.doi.org/10.1127/ejm/2017/0029-2686.

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Llorens, T., e M. C. Moro. "MICROLITE AND TANTALITE IN THE LCT GRANITIC PEGMATITES OF LA CANALITA, NAVASFRIAS Sn-W DISTRICT, SALAMANCA, SPAIN". Canadian Mineralogist 48, n. 2 (1 aprile 2010): 375–90. http://dx.doi.org/10.3749/canmin.48.2.375.

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Dill, H. G., S. Kaufhold e R. Dohrmann. "A late-stage hydrothermal phosphate-bearing montmorillonite argillitization from the tourmaline-bearing pegmatite of Alto dos Quintos Mine, northeast Brazil". Clay Minerals 46, n. 3 (settembre 2011): 473–85. http://dx.doi.org/10.1180/claymin.2011.046.3.473.

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AbstractThe Alto dos Quintos Mine, Rio Grande do Norte, northeast region of Brazil, is one of the few mines where a LCT (Li-Cs-Ta-enriched) pegmatite is exploited for the deep blue gemstone called “Paraiba Tourmaline (PT)”. Blue cuprian elbaite, a fault-bound pink montmorillonite bearing some relict apatite and newly-formed Ca-Al-phosphate of the Al-P-sulphate group (APS minerals) also occur in the underground mine. The montmorillonite was studied using extended clay mineralogical tools (XRD, IR spectroscopy, XRF, SEM-EDX, cation exchange capacity (CEC), DTA). The structural formula method for calculation of the smectite formula based on EDX data yielded an extremely Fe-poor montmorillonite: (Ca0.22+)(Al1.7Fe0.0Mg0.4)(Si3.8Al0.2). The charge on the tetrahedral sheets accounts for approximately 30% of the total permanent negative charge. However, based on the more precise Hofmann & Klemen test, tetrahedral charge values of 11% to 13% were calculated. This is indicative of the dominance of montmorillonite rather than beidellite among the smectite minerals, which is independently proved by a pronounced IR band at 630 cm-1. The formation of pink montmorillonite is not directly related to the emplacement of the Li-bearing PT pegmatite. The sheet silicate developed after a considerable hiatus (Mesozoic?), when the Neoproterozoic pegmatites had already undergone different stages of hypogene (cookeite) and supergene (illite, kaolinite) alteration, during which Li was flushed out to a degree that formation conditions of expandable Li-bearing phyllosilicates were no longer favoured. The nature of the pinkish tint is not yet clarified. The montmorillonite formed in a temperature regime close to 250°C, when apatite was transformed into Ca-bearing APS minerals under acidic conditions. Cainozoic volcanic activity and the reactivation of deep-seated fault zones are considered to be responsible for the formation of this pink P-bearing montmorillonitic clay.

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Langhof, Jörgen, Dan Holtstam e Lars Gustafsson. "Chiavennite and zoned genthelvite-helvite as late-stage minerals of the Proterozoic LCT pegmatites at Utö, Stockholm, Sweden". GFF 122, n. 2 (giugno 2000): 207–12. http://dx.doi.org/10.1080/11035890001222207.

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Novak, M., R. Skoda, P. Gadas, L. Krmicek e P. Cerny. "Contrasting Origins of the Mixed (NYF + LCT) Signature in Granitic Pegmatites, with Examples from the Moldanubian Zone, Czech Republic". Canadian Mineralogist 50, n. 4 (1 agosto 2012): 1077–94. http://dx.doi.org/10.3749/canmin.50.4.1077.

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MATONDO, Idylle Plachini LOUFOUANDI, e Mikhail IVANOV. "Composition and probable ore igneous rocks source of columbite from alluvial deposits of Mayoko district (Republic of the Congo)". Journal of Mining Institute 242 (24 maggio 2020): 139. http://dx.doi.org/10.31897/pmi.2020.2.139.

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The article presents the results of optical, electron microscopic and electron microprobe studies of columbite group minerals, collected during heavy mineral concentrate sampling of alluvial deposits in the Mayoko region (Republic of the Congo). The aim of the study is revealing tantalum niobates ore body in this region. We found that these minerals in loose deposits are represented by two grain-size groups: less than 1.6 mm (fine fraction) and 1.6-15 mm (coarse fraction). The grains of both fractions belong mainly to columbite-(Fe), less often to columbite-(Mn), tantalite-(Mn) and tantalite-(Fe), contain impurities of Sc, Ti, and W. The crystals have micro-scaled zoning (zones varies slightly in the Ta/Nb ratio values) and contains a lot of mineral inclusions and veins represented by zircon, pyrochlore supergroup minerals and others. Columbite-(Fe) and columbite-(Mn) are characterized by an increased content of Ta2O5 up to the transition to tantalite-(Fe) and tantalite-(Mn). This allows us to exclude the formation of subalkaline rare-metal granites, their metasomatites (albitites and greisenes) and carbonatites, from the list of possible columbite ore rocks source in the Mayoko district. Thus, beryl type and complex spodumene subtype rare-element pegmatites of the mixed petrogenetic family LCT-NYF (according to P.Černý) should be considered as a probable root source. The results of the research should be taken into account when developing the methodology for prospecting in this area.

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Lisboa, Vinicius Anselmo Carvalho, Juana Cristina de Abreu Macedo, Agda Rayanna Santos Pereira, Letícia Verônica Noberto e Manoel Pereira Galdino. "Aspectos da geologia e mineralogia do pegmatito Alto do Patrimônio, província pegmatítica da Borborema". Estudos Geológicos 33, n. 1 (31 gennaio 2024): 119–36. http://dx.doi.org/10.51359/1980-8208.2023.257886.

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O Pegmatito Alto do Patrimônio (PAP) localiza-se ao norte do estado da Paraíba, na cidade de Pedra Lavrada. Este corpo pegmatítico é, atualmente, explorado para a extração de minerais industriais. Está inserido no contexto da Província Pegmatítica da Borborema, intrudindo os metassedimentos da Formação Seridó. Esta província é mundialmente conhecida desde a II Guerra Mundial por seus pegmatitos mineralizados principalmente em tântalo-nióbio, berílio, estanho, lítio e minerais-gemas. Assim, o presente trabalho tem foco no mapeamento geológico de detalhe do PAP. O corpo apresenta comprimento com cerca 120 m de extensão, com espessura máxima de 46m, está orientado segundo as direções N-S. Exibe um zoneamento mineral bem definido, a saber: i) zona de borda (zona I); ii) zona de muro (zona II); iii) zona intermediária (zona III) e iv) núcleo de quartzo (zona IV). As zonas I e II contêm a mesma mineralogia essencial, composta por quartzo, feldspatos e micas. A zona III também é composta por quartzo, feldspatos e micas; é nela onde está concentrada a maior parte dos minerais de interesse econômico (principalmente a tantalita-columbita e o berilo). Na porção mais interna do pegmatito, o núcleo de quartzo, composto por quartzo leitoso e rosáceo. Esse zoneamento mineral observado permite classificá-lo como um pegmatito do tipo heterogêneo. A identificação desta mineralogia permitiu categorizá-lo como um pegmatito da família LCT, da classe dos pegmatitos ricos em elementos raros (ELR).

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Freire, Débora Macedo do Nascimento, Lucilene dos Santos, José Gervásio Freire, Bruno Sousa Araújo e Alejandro Pedro Ayala. "Caracterização cristalográfica e cristaloquímica de uma turmalina - (Fe) oriunda de pegmatito da região de Solonópole no estado do Ceará". Estudos Geológicos 33, n. 1 (1 aprile 2024): 89–101. http://dx.doi.org/10.51359/1980-8208.2023.261513.

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O Distrito Pegmatítico de Solonópole-Banabuiú (DPSB) está localizado na porção centro-oeste do Estado do Ceará, encaixado no embasamento paragnáissico do Domínio Ceará Central da Província Borborema. É o de maior expressão econômica da região e tem suas principais mineralizações associadas ao caráter lítio-berilo-tantalífero dos corpos. Nesta pesquisa foi selecionado um pegmatito localizado no município de Solonópole no DPSB. É classificado como pegmatito misto entre os tipos homogêneo e heterogêneo, não apresentando zoneamento bem definido. É um pegmatito complexo, formando corpos de substituição (bolsões) de muscovita, quartzo e berilo, com cristais bem desenvolvidos. Enquadra-se na classe dos Elementos Terras Raras, da família LCT. Sua mineralogia difere de outros pegmatitos da região pela presença de minerais de lítio, a turmalina apresenta uma variação de cor do verde para azul. A caracterização cristaloquímica se deu por análise de microssonda eletrônica e a amostra obteve os seguintes teores para elementos maiores (Al2O3=34,18%, MgO=1,10%, FeO=11,44%) classificada como elbaíta/oxi-schorlita. As turmalinas do Pegmatito de Solonópole são oxi-espécies, caindo no limite do campo dos pegmatitos graníticos e aplitos ricos em Li e estágio endogranítico/endogreisen. A caracterização cristalofísica através da difração de raios-X em monocristal foi realizada em amostras de turmalina, apresentando uma estrutura cristalina romboedral, grupo espacial R3m e os parâmetros da cela unitária sendo a=15,90 Å, b=15,90 Å e c=7,12 Å, considerados favoráveis para um cristal de turmalina rica em Fe.

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Hulsbosch, Niels, Johanna Van Daele, Nathan Reinders, Stijn Dewaele, Dominique Jacques e Philippe Muchez. "Structural control on the emplacement of contemporaneous Sn-Ta-Nb mineralized LCT pegmatites and Sn bearing quartz veins: Insights from the Musha and Ntunga deposits of the Karagwe-Ankole Belt, Rwanda". Journal of African Earth Sciences 134 (ottobre 2017): 24–32. http://dx.doi.org/10.1016/j.jafrearsci.2017.06.004.

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LEMOS, Wagner Travassos, Marcelo dos Santos SALOMÃO, Luiz Carlos BERTOLINO e Francisco José da SILVA. "OCORRÊNCIAS DE CASSITERITA E DE MINERAIS DO SUBGRUPO DA COLUMBITA NOS MUNICÍPIOS DE CONSELHEIRO LAFAIETE, CARANAÍBA E CRISTIANO OTONI, SUL DO ESTADO DE MINAS GERAIS." Geosciences = Geociências 42, n. 4 (15 gennaio 2024): 467–79. http://dx.doi.org/10.5016/geociencias.v42i4.18125.

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RESUMO - Os municípios de Conselheiro Lafaiete, Caranaíba e Cristiano Otoni, no estado de Minas Gerais, estão inseridos na compartimentação tectônica denominada de Cinturão Mineiro. Esta região é considerada como uma extensão da Província Pegmatítica de São João del Rei, conhecida pelas suas mineralizações de Sn, Nb, Ta e Li. As principais unidades presentes correspondem ao Granito Cupim e o Gnaisse Caatinga. O mapa aerogeofísico da Amplitude do Sinal Analítico exibe uma assinatura diferenciada para o granito Cupim, e sugere uma área não cartografada associada a essa unidade. O mapa Gamaespectrométrico do elemento urânio exibe valores superiores a 3 ppm para o Granito Cupim e parte do Gnaisse Caatinga. As análises litogeoquímicas demostraram que o Granito Cupim é resultado de um magmatismo intraplaca. O Gnaisse Caatinga exibe resultado compatível a ambiente de arcos magmáticos acrescionários. O pegmatito foi classificado como sendo do tipo LCT de acordo com Cerný & Ercit (2005), e está associado ao Granito Cupim. Foram identificados 15 pontos mineralizados com cassiterita e minerais do subgrupo da columbita em drenagens, placeres, pegmatito e garimpos abandonados. As análises no MEV-EDS em grãos de cassiterita indicaram a presença de inclusões de tantalita e nióbio, e alto teor de estanho. Palavras-chave: Cassiterita. Columbita. Cinturão Mineiro. Conselheiro Lafaiete. Caranaíba. Cristiano Otoni. ABSTRACT - The municipalities of Conselheiro Lafaiete, Caranaíba and Cristiano Otoni, in the state of Minas Gerais, are inserted in the tectonic compartmentation called Cinturão Mineiro. This region is considered as an extension of the São João del Rei Pegmatite Province, known for its Sn, Nb, Ta and Li mineralizations. The principal units present are Cupim Granite and Caatinga Gneiss. The aerogeophysical map of the Analytical Signal Amplitude displays a different signature for the Cupim granite, and suggests an uncharted area associated with this unit. The Gammaspectrometric map of the element uranium shows values above 3 ppm for the Cupim Granite and part of the Caatinga Gneiss. Lithogeochemical analyses demonstrated that the Cupim Granite is the result of intraplate magmatism. The Caatinga Gneiss displays results compatible with an accretionary magmatic arc environment. The pegmatite was classified as being of the LCT type according to Cerný & Ercit (2005), and is associated with the Cupim Granite. Fifteen mineralized samples with cassiterite and minerals from the columbite subgroup were identified in creeks, placers, pegmatite and abandoned mines. SEM-EDS analyses of cassiterite grains indicated the presence of tantalite and niobium inclusions, and a high tin content. Palavras-chave: Cassiterite. Columbite. Mineiro Belt. Conselheiro Lafaiete. Caranaíba. Cristiano Otoni. .

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Galliski, Miguel A., Encarnación Roda-Robles, Frédéric Hatert, María Florencia Márquez-Zavalía e Viviana A. Martínez. "The Phosphate mineral assemblages from La Viquita Pegmatite, San Luis, Argentina". Canadian Mineralogist 58, n. 6 (1 novembre 2020): 733–46. http://dx.doi.org/10.3749/canmin.1900106.

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ABSTRACT La Viquita is a rare-element pegmatite of LCT signature, REL-Li subclass, spodumene subtype, that shows Fe > Mn mineral paragenesis instead of Mn > Fe, which is more common in the rare-element pegmatite population of the San Luis ranges. The phosphate mineral association of this pegmatite can be subdivided into (1) primary, with dendritic triphylite [(Fe/(Fe + Mn) = 0.72] and montebrasite–amblygonite as main phases; (2) metasomatic, with subsolidus replacement of triphylite by ferrisicklerite and heterosite; and (3) hydrothermal, with secondary growth of alluaudite at the expense of heterosite and wardite from montebrasite caused by Na-metasomatism. A Ca-rich influx under oxidizing conditions produced childrenite–eosphorite–ernstite, jahnsite-(CaMnFe), and kingsmountite. Apatite-group minerals are present throughout the processes. Very late-stage solutions formed millimetric crystals of hydroxylherderite associated with hydroxylapatite in cavities in K-feldspar.

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Pfister, Jérémie D., Daniel J. Kontak e Lee A. Groat. "Textural and Mineralogical Evolution of the Little Nahanni Pegmatite Group (NWT, Canada) with Implications for Metasomatism, Rare-Metal Mineralization, and Pegmatite–Wall Rock Interaction". Canadian Journal of Mineralogy and Petrology 61, n. 3 (1 maggio 2023): 467–505. http://dx.doi.org/10.3749/2000086.

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Abstract Situated in the Northwest Territories (Canada), the Cretaceous (ca. 85 Ma) Little Nahanni Pegmatite Group is an LCT-type pegmatite swarm enriched in Li, Sn, and Ta. Displaying intensive albitization associated with rare-metal mineralization (i.e., Nb, Ta, Sn), having a notably high surface-area-to-volume ratio (i.e., hundreds of thin dikes), and being particularly well exposed in a suite of thirteen glacial cirques, the Little Nahanni Pegmatite Group provides an ideal opportunity to investigate some unresolved aspects of pegmatite formation and evolution, such as metasomatism, pegmatite–wall rock interaction, and the nature and origin of rare-metal mineralization (i.e., magmatic versus metasomatic). Using an integrated approach combining field observations with detailed textural and mineralogical studies, two different stages of pegmatite evolution are documented: primary magmatic followed by intense metasomatism. Preservation of primary magmatic features, such as coarse oriented high aspect-ratio crystals (spodumene, K-feldspar), banded aplites, anisotropic fabrics, and skeletal textures, highlight the importance of undercooling (ΔT) of the melt with consequent disequilibrium crystallization and boundary layer effects. The metasomatic stage is dominated by the formation of domains of secondary albite and is attributed to interaction with a residual highly fluxed sodic melt and is responsible for most of the rare-metal mineralization; less abundant micaceous units and cafemic domains reflect incursion of acidic magmatic-sourced and alkaline wall rock derived fluids. Our findings are significant and have widespread application to all pegmatite types. Particularly significant is the finding that the rare-metal mineralization is mostly localized to zones of metasomatism.

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Foord, Eugene E. "Clinobisvanite, eulytite, and namibite from the pala pegmatite district, San Diego Co., California, USA". Mineralogical Magazine 60, n. 399 (aprile 1996): 387–88. http://dx.doi.org/10.1180/minmag.1996.060.399.14.

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The 100 Ma complex LCT-type composite pegmatite- aplite dykes, intruded into various units of the Southern California Batholith, are known to contain bismuth minerals. Jahns and Wright (1951) reported the following primary and secondary bismuth minerals from the quartz-rich cores of a number of dykes in the Pala district, San Diego Co., California: native bismuth, bismuthinite, bismite, bismutite, and beyerite.

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Perring, Sophie, e Nigel Brand. "Rapid field identification of LCT pegmatite mineralogy: Application of portable Raman spectroscopy". ASEG Extended Abstracts 2019, n. 1 (11 novembre 2019): 1–3. http://dx.doi.org/10.1080/22020586.2019.12073039.

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Simmons, William, Alexander Falster, Karen Webber, Encarnación Roda-Robles, Andrew P. Boudreaux, Leah Rae Grassi e Gary Freeman. "Bulk Composition of Mt. Mica Pegmatite, Maine, USA: Implications For the Origin of An Lct Type Pegmatite By Anatexis". Canadian Mineralogist 54, n. 4 (luglio 2016): 1053–70. http://dx.doi.org/10.3749/canmin.1600017.

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Aderogbin, J. A., e O. A. Okunlola. "Compositional characteristics and Ta-Sn-Nb rare metal mineralization potential of Egbe Pegmatite, Southwestern Nigeria". Global Journal of Geological Sciences 18 (3 novembre 2020): 49–62. http://dx.doi.org/10.4314/gjgs.v18i1.5.

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Pan African (600 ± 150) pegmatite which intrudes gneisses, amphibolites, quartzite and schists around Egbe area were studied for their compositional features. This is with a view to characterizing and assessing their potential for rare metal Ta-Sn-Nb mineralization. Twenty seven samples comprising eleven (11) whole rock, sixteen (12) muscovite extracts and four (4) feldspar extracts samples were analyzed using the Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). Major oxide geochemical assessment of the whole rock pegmatite indicates that the pegmatite is siliceous (79.82% SiO2) and moderately high in Al2O3 (12.22%). The K2O, Na2O contents are averagely 2.25% and 2.87% respectively while Fe2O3, MnO, MgO are each less than 1.0%. Average values of trace elements in the pegmatite are Ta (52.55ppm), Sn (92.3 ppm), Rb (1083.5ppm), Nb (109.35 ppm), Cs (32.12ppm), Sr (17.84 ppm), Y (9.86 ppm), and Zr (41.27 ppm), Ba (50.47ppm), Hf (12.38ppm), Zr (41.27ppm), Ga (32.12ppm) and W(2.91PPM) and ratios of diagnostic elements are K/Rb (30.27), Rb/Sr (298.93), Zr/Hf (7.23), Rb/Cs (65.80), K/Cs (1103.11), Ta/W (41.81), Nb/Ta (55.397) Na/Rb (41.77) and Na/K (92.25) A/CAN >1and Al2O3>CaO+ Na2O+ K2O with enrichment of SiO2, Al2O3, Na2O, K2O and depletion of Fe2O3, MnO2 and MgO suggests that Egbe pegmatite is of peraluminous bulk composition and plots of A/NK vs Al/CNK and Rb vs (Y+Nb) discriminates Egbe pegmatite in the peraluminous LCT (Li, Rb, Cs, Be, Ga, Nb <,> Ta, Sn, Hf, B, P, F) of syncollisional to within plate granitic family. The Ta/W vs Cs plot for the three sample media shows the relationship between increasing Ta/W ratio and elemental fractionation as indicated by Cs. The K/Rb vs Cs and K/Rb vs Rb plots for the three sample media further establishes the rare – metal nature and mineralization potential of Egbe pegmatite. Using the discriminant plots of TaVs Rb, Ta vs Cs .TaVs K/Cs, and Ta Vs (Cs+Rb) where most of the samples of the whole rock pegmatite and mineral extracts plots above the Beus line and about 30% plotting above the Gordinyenko line respectively. Overall geochemical assessment is that Egbe pegmatite is a rare metal, highly fractionated Beryl type with rare metal enrichment trend of Nb>>Sn>>Ta. Keywords: Pegmatite, Peraluminous, Syncollisional, Within-plate, Discriminant, Fractionation, Sample media

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Lei, Xiu-Fang, Shao-Yong Jiang, Rolf L. Romer, Hui-Min Su, Ming-Yu Cao e Chen-Lei Zhao. "Petrogenesis of the Weiling beryl-bearing granitic pegmatite – A giant LCT-type pegmatite in the Northern Wuyi area, South China". Ore Geology Reviews 160 (settembre 2023): 105572. http://dx.doi.org/10.1016/j.oregeorev.2023.105572.

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Galliski, Miguel Ángel, María Florencia Márquez-Zavalía e Diego Sebastián Pagano. "Metallogenesis of the Totoral LCT rare-element pegmatite district, San Luis, Argentina: A review". Journal of South American Earth Sciences 90 (marzo 2019): 423–39. http://dx.doi.org/10.1016/j.jsames.2018.12.018.

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