PHOSPHATE SEQUENCE STUDY OF BOQUEIRÃO PEGMATITE (RIO GRANDE DO NORTE STATE, BRAZIL)

Sandra Amores Casals1 Sandra de Brito Barreto2 Ruben Espallargas3 François Fontan4 Joan Carles Melgarejo Draper5

1,5Departament de Cristalografia, Mineralogia i Dipòsits Minerals. Facultat de Geologia, Universitat de Barcelona –Spain; [email protected]; [email protected] 2Departamento de Geologia, Universidade Federal de Pernambuco,Recife (Pernambuco, Brasil). [email protected] 3Institut de Ciencies de la Terra Jaume Almera (ICTJA-CSIC). Barcelona Spain. [email protected] 4CNRS-Université Paul Sabatier, Toulouse (France).

RESUMO

O pegmatito Boqueirão localiza-se naProvíncia Pegmatítica daBorborema, no estado do Rio Grande do Norte (Nordeste do Brasil), encontra-se encaixado em metaconglomerados de idade neoproterozóicada Formação Equador. Trata-se de um pegmatito zonado concentricamente, exibindo diferentes zonas caracterizadas por suas mineralogias. As zonas de contato e de parede são compostas essencialmente por quartzo, microclina e moscovita exibindo muitas vezes texturas esqueléticas e gráficas, e,tendo como minerais acessórios a turmalina e a granada. A zona intermediária é dividida em duas subzonas distintas e mostra uma mineralogia diversa exibindo uma complexa associação de fosfatos, berilo, columbita-tantalita e zircão. A zona mais interna é principalmente constituída por um núcleo de quartzo. Além disso, observa-se corpos de substituição típicos, constituídos por albita,situados na parte oriental do corpo. Litofilita - triplilita representa a fase de fosfato mais abundante exibindo exsoluções de sarcopsida e substituição por sicklerita, resultante da alteração por Li- lixiviação, mais conhecida como Série de Quensel-Mason. A ausência de membros da série heterosita-purpurita é notável. Fosfatos primários, tais como montebrasita e triplita são também observados. Subsequentemente, a presença de alluaudita e varulita sugere que o pegmatito foi submetido a metassomatismo sódico.Toda esta assembléia de minerais sofreu uma extensa alteração que levou a cristalização de fosfatos secundários. Dados de microssonda eletrônica em trifilita-litiofilita revelam razões Mn/(Mn + Fe) entre 0,21-0,24 e também até 0,72 que sugerem um magma de origem pouco fracionado; consequentemente, a ferrisicklerita mostra valores de Mn/(Mn + Fe)entre 0,69-0,77, característicos de elevado grau de evolução, sugerindo que o pseudomorfismo foi produzido por uma elevada interação entre rocha/fluido. Alluaudita e varulita também revelam conteúdos de Mn e Fe até 0,71 semelhantes aos fosfatos precursores. Além disso, oito diferentes fosfatos secundários foram identificados substituindo fases primárias, quer como pseudomorfos ou cortando-as. Ocorrem como cristais euédricos de grã fina, esferulíticos ou maciços, com cores vivas facilmente identificados. As fases secundárias ricas em Mn são hureaulita, eosphorita, whiteita, jahnsita e serrabrancaita, enquanto que lipscombita, phosphosiderita e mitridatita

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Sandra Amores Casals et al. correspondem a associação secundária rica em ferro (Fe). A origem supergênica tardia e a entrada fluidos ricos Ca, K e Mg procedentes da rocha hospedeira são sugeridos como responsáveis pela formação destes fosfatos. Não há quaisquer feições que os correlacionem a cristalização do pegmatito. O conteúdo de Háfnio (Hf) de zircões encontrados na zona intermediária tem sido analisado por microssonda eletrônica, e, usado como um poderoso indicador do grau de evolução do pegmatito, juntamente com o conteúdo de Mn dos fosfatos. O conteúdo Hf obtido é baixo chegando até 5% em peso de HfO2, que revela um magma pegmatítico pouco fracionado. Além disso, a presença de silicatos ferromagnesianos que constituem a mineralogia de zonas do pegmatito, como a turmalina rica em Fe, a granada e o berilo verde está de acordo com esta hipótese. Portanto, o Pegmatito Boqueirão corresponde a um pegmatito de elementos raros subtipo berilo-columbita-fosfato.

Palavras chave: Pegmatitos graníticos, fosfato, Boqueirão, Brasil.

ABSTRACT

The Boqueirão pegmatite is located in the Borborema Pegmatite Province in the state of Rio Grande do Norte (NE Brazil) hosted by Neoproterozoic metaconglomerates of Equador Formation. The pegmatite occurs as a concentric body displaying characteristic units according their mineralogy. The border and wall zones are composed by quartz, microcline and muscovite often displaying skeletal and graphic textures with accessory tourmaline and garnet. The intermediate zone is divided in two distinct subzones and shows a complex mineralogy exhibiting a varied phosphate association, beryl, columbite-tantalite and zircon. The innermost zone is mainly constituted by a quartz core. In addition, typical replacement bodies of albite are recognized at the eastern part of the body. Lithiophilite – triphylite represents the most abundant phosphate phase exhibiting exsolutions of sarcopside and replaced by sicklerite due to Li-leaching alteration, best known as Quensel Mason sequence. The scarcity of heterosite-purpurite series is remarkable. Montebrasite and triplite are also primary phosphates observed. Subsequently, the presence of alluaudite and varulite occurrences suggests that Na-metasomatism affected the pegmatite. The whole ensemble is crosscut by an extensive alteration that resulted in secondary phosphate minerals. Electron microprobe data of triphylite-lithiophilite shows Mn/(Mn+Fe) ratios between 0.21-0.24 but also up to 0.72 which seems to indicates that the earlier pegmatite magma could be slightly fractionated; consequently, ferrisicklerite shows Mn/(Mn+Fe) values between 0.69-0.77 in agreement with high evolution degree and suggesting that pseudomorphism may be produced by high rock/fluid ratios. Alluaudite and varulite also record Mn and Fe contents up to 0.71 similar to precursor phosphates. Furthermore, eight different secondary phosphates have been identified as replacement of primary phases either as pseudomorphs or crosscutting them. They form euhedral crystals of fine grain size, spherulites or extensive masses displaying vivid colours which are easily identifiable. Mn-rich secondary phases are hureaulite, eosphorite, whiteite, jahnsite and serrabrancaite while lipscombite, phosphosiderite and mitridatite correspond to Fe-rich secondary association. Supergenic late origin and entrance of Ca-, K-, Mg-rich fluids from host rock may be invoked in order to explain their formation. They do not show any relationship with processes of pegmatite crystallization. Hf content of zircon from the intermediate zone has been analysed by electron microprobe as a powerful indicator of pegmatite evolution degree together with Mn content of phosphates. Hf content obtained is low up to 5% wt. of HfO2 which points out to low

4 Estudos Geológicos vol. 24(2) 2014 www.ufpe.br/estudosgeologicos Phosphate sequence study of Boqueirão pegmatite... fractionated pegmatite magma. Besides, the presence of ferromagnesian silicates forming the pegmatite units such as Fe-rich tourmaline, garnet and green beryl is in agreement of that hypothesis. Therefore, Boqueirão corresponds to rare element pegmatite of beryl-columbite-phosphate subtype.

Keywords: Granitic pegmatite, phosphate, evolution, Boqueirão, Brazil.

INTRODUCTION Boqueirão pegmatite is located The Boqueirão pegmatite is located near the city of Parelhas in the state of in the state of Rio Grande do Norte, Rio Grande do Norte, Brazil. It is Northeastern Brazil and belongs to hosted in a geotectonic region best Borborema Pegmatitic Province (BBP). known as Borborema Province (Fig. 1), The BBP is known since the beginning which comprises the west-central part of 20th century for mica extraction and of a Pan African-Brasiliano tectonic during the Second World War it became collage that formed as a consequence of best known not only as one of the most late Neoproterozoic (ca. 600 Ma) important Ta-Be producers but also for assembly of West Gondwana (Van its exotic Nb – Ta oxide production Schmus et al., 2003). Most of the (Beurlen et al., 2008). Recently, it province consists of Paleoproterozoic to became an important supplier of raw Archean basement blocks with material for the Brazilian ceramics Neoproterozoic metasedimentary and industry (Beurlen et al., 2009). In metavolcanic sequences forming major Boqueirão, feldspars and micas have fold belts, and voluminous plutonic been mined together with different magmatism. The eastern part of the amounts of beryl and Ta-bearing province can be divided into three major minerals as sub products. In addition, tectonic domains: the Rio Grande do phosphate nodules are frequent. As Norte domain (RGND), to the north of mentioned in previous studies, rare- the Patos shear zone; a central domain elements mineralization has been between the Patos and Pernambuco associated to phosphates, therefore, its shear zones; and a southern domain presence could be a good criterion for (SD) between the Pernambuco shear field exploration (Černý et al., 1997: zone and the São Francisco craton London, 2008). (SFC). The western part may be divided In spite of last century importance, into two main tectonic domains: Ceará very few geological studies were and Médio Coreau domain. The area performed about the BPP in the last covered in this work is located in the fifty years. The aim of this contribution southeastern part of Seridó fold belt is to establish a paragenetic sequence (Beurlen et al., 2008). Seridó fold belt and mineral chemistry of primary, comprises two essential units, basement metasomatic and secondary phosphates and metasedimentary sequences known in order to evaluate the degree of as the Seridó Group (Soares et al., evolution of the pegmatite and to 2008). Neoproterozoic basement is establish the processes that operated formed by Caicó Complex composed by during the formation of Boqueirão gneisses and migmatites formed around pegmatite. 2.2 Ga, and Sao Vicente Complex composed by schist, quarzites, GEOLOGICAL SETTING amphybolites and marbles (Baumgartner et al., 2006).

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Seridó Group is composed by schists, marbles and calcsilicate rocks at supracrustal rocks formed during the the top. On the top, Seridó Formation is Meso- and Neoproterozoic, discordantly represented by aluminous metapelites over the Paleoproterozoic Caicó with variable amounts of garnet, Complex (2.2 Ga). It is divided into cordierite, staurolite, andalusite and three formations from the bottom to the sillimanite. The Boqueirão pegmatite is top of Jucurutú formation constituted intruding quartzites, metarkoses and for biotite-rich gneisses interlayered metaconglomerates of the Equador with limestone or calc silicate beds. Formation, as about 11% of mineralized Equador formation is composed for rare-element granitic pegmatites of muscovite-rich quartzite, in addition of Borborema Province (Beurlen et al., polimictic metaconglomerates, gneisses, 2008).

Figure 1- Location and geological setting of the Boqueirão pegmatite (BP) inside the Borborema Pegmatitic Province. The BP is hosted by the Neoproterozoic Equador Formation. Modified after Soares et al. (2011).

ANALYTICAL METHODS using a CAMECA SX-100, by analysts A sequence of transmited-reflected Dr. De Parseval and Dr. Fontan, at optical mineralogy and electron Laboratoire de Minéralogie at Paul microprobe analyses was used to Sabatier University (Toulouse, France) identify phosphate minerals. and a CAMECA SX-50 at Centres Quantitative analyses of major elements Científics i Tecnològics of the were performed with wavelength- University of Barcelona by Dr. Llovet. dispersive spectrometry (EMPA-WDS)

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Operating conditions were minor minerals such as schorl, garnet accelerating voltage of 15 kV was and occasionally löllingite, sometimes combined with a beam current of 15 nA associated with bismuthinite, are and 2µ spot beam diameter. The present. structural formulae of phosphates were The intermediate zone is divided in calculated based on (PO4)3- tetrahedron. two subzones: the first one (A), in the Calculation of other components such outer part, is characterized by 3+ as H2O, F and Fe was done using intergrowth between perthitic white charge balance and stoichiometry. microcline with exsolved grey quartz giving rise graphic texture with STRUCTURE OF BOQUEIRÃO additional amounts of albite, muscovite, PEGMATITE beryl, sometimes columbite-tantalite group minerals and commonly zircon. B Boqueirão pegmatite is a thick intermediate zone has coarser grain size dyke 50 metre wide exposed over a forming one-meter-long crystals. The distance of 400 m, striking mineralogy is more complex than approximately NW-SE crosscutting previous units and consists of quartz, metaconglomerates of Equador perthitic microcline, albite, muscovite, Formation and presenting or developing phosphates (Fig. 3a), beryl, columbite- tourmalinization around its contact. tantalite group minerals and zircon (Fig. Concentric units are only observed in 5f). Phosphate minerals occur as the central part of the pegmatite, nodular or skeletal morphology with whereas the western part is poorly complex and little-known paragenetic zoned or unzoned. Those units are relationships. The innermost part is distinguished by different mineralogy essentially constituted by quartz (Fig. and mineral textures following the usual 3b). nomenclature for pegmatite zoning Typical replacement bodies are according to Cameron (1948) and Černý recognized highly developed at the (1991) criteria in: border and wall zone, eastern part, where an association of outer and inner intermediate zone and fine-grained saccharoidal albite (Fig. quartz core (Fig. 2). 5h), muscovite and quartz generates a The outer zones are mainly total replacement of wall and composed by a border and a wall zone intermediate zones (Fig. 2 and 3b). In with fine grain quartz and muscovite. addition, albite veins are observed Graphic intergrowth and equigranular throughout the whole pegmatite as well textures develop in the wall zone. Other as quartz-muscovite veinlets (Fig. 3c).

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Figure 2: Sketch of Boqueirão pegmatite inner structure. The main units are represented; border zone (orange), wall zone (pink), intermediate zone (two different green) and the quartz core (grey) with replacement bodies. Modified from Beurlen et. al (2008).

Figure 3: A) Phosphate crystals with coarse grain size, at intermediate zone; B) albite replacement bodies (white and rose colored) overlapping intermediate zone; C) detail of quartz-muscovite late veinlets.

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PETROGRAPHY AND 1990; Hatert et al., 2006). MINERAL CHEMISTRY Ferrisicklerite-sicklerite is easily identifiable under microscope as orange According to Moore (1982) crystals with visible exfoliation and phosphate classification, primary, pleochroism, maintaining optical metasomatic and secondary phosphates continuity with previous lithiophilite- have been identified composing the B triphylite crystals that grows inside intermediate zone (Fig. 4). them (Fig. 5b, c). Heterosite-purpurite is extremely scarce. Triplite and Primary phosphates amblygonite form allotriomorfic equidimensional crystals of several Triphylite – lithiophilite are the decimeters long replaced by secondary most abundant minerals and constitutes phosphates and manganese oxides. nodular greenish-grey equidimensional Amblygonite is less abundant. crystals. They are usually intergrown Triphylite – lithiophilite with two generation of sarcopside: the composition show variable Mn and Fe first one commonly appears as fine content. Based on that, in the Mn-rich grain exsolution (3 µm long) regularly triphylite the ratio Mn/(Mn+Fe) varies parallel arranged in triphylite crystals. between 0.21 – 0.24 and in the Fe-rich The second generation is constituted by lithiophilite this ration reaches 0.72. Fe- 1 mm long crystals with randon rich sarcopside exsolutions display low orientation near the crystal rims or Mn/(Mn+Fe) ratio between 0.23 and fractures (Fig. 5a). Triphylite – 0.24 which remain similar to Mn-rich lithiophilite are often replaced following triphylite ratio (Fig. 5). Sicklerite has Li-leaching, by ferrisicklerite – high Mn/(Mn+Fe) ratios between 0.69 sicklerite, heterosite – purpurite and and 0.77 suggesting that this alluaudite in a process best known as replacement may be produced by high Quensel – Mason Sequence (Fontan et rock/fluid ratios. al., 1976; Corbella and Melgarejo,

Figure 4: Chemical composition of phosphate occurrences which are present in the Boqueirão pegmatite.

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Figure 5. Images of different phosphate associations obtained by transmitted light microscope. A) Triphylite (Trp) with two generation of sarcopside exsolutions (Sar) (x5, xp); B) lithiophilite (Lph) replaced by sicklerite (Sck) (x2, pp); C) Sicklerite crystals (reddish orange) replaced by yellowish alluaudite (Ald) (x5, pp); D) lithiophilite and sicklerite replaced by varulite (Vr) and later by lipscombite (lcb) (x2, pp); E) Colorless hureaulite II (HurII) cuts phosphosiderite violet aggregates (Psh) and jahnsite (Jhn) (x20, pp); F) zircon with eosphorite (Eos) (x5, pp); G) eosphorite cuts albite (Ab) (x2, xp); H) fine grain aggregate of albite replacing a sicklerite crystal (x2, pp).

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Metasomatic phosphates phosphates. They present different colors in hand sample (lipscombite The appearance of a metasomatic reddish orange, phosphosiderite purple stage related to Na enrichment is and mitridatite greenish brown) and characterized by alluaudite and varulite with the use of electron microprobe replacing sicklerite and triplite, analyses, assure their identified (Table respectively, distributed along thin 1). Moreover, serrabrancaite also has veins and fractures. They display pale been observed as hydrous manganese green or yellow hypidomorphic crystals phosphate. It can be confused with Mn up to 1 mm long with very short or Fe oxides suggesting that it can be prismatic habit and visible exfoliation more abundant. Serrabrancaite was (Fig. 5c). Regarding mineral chemistry, discovered in Serra Branca pegmatite, alluaudite Mn/(Mn+Fe) ratio are close located few kilometers SE, as alteration to 0.71, the same observed for Fe-rich product of triplite (Witzk et al., 2000). lithiophilite and sicklerite. Zircon Secondary phosphates Zircon crystals are observed in Besides previous phosphates, a both intermediate zones often altered by great number of idiomorphic phosphates uraninite veins and galena (Fig. 4f). As are replacing earlier phases displaying pointed out by London (2008), Hf/Zr radial aggregates and infilling veins or ratio corresponds to another interesting cavities. Hureaulite is one of the most indicator of the evolution of the abundant secondary phase, occurring as pegmatites. Hence, analyses reveal low fibrous crystals distributed in Hf content (up to 5% HfO2). millimetric veins. Two generations are distinguished: hureaulite I replaces DISCUSSION AND CONCLUSIONS sicklerite or triphylite – lithiophilite following exfoliation discontinuities, Paragenetic sequence while hureaulite II, latter in origin, overlaps other supergenic phosphates During the first intermediate zone (Fig. 5d). Eosphorite replace Mn-Fe formation, primary phosphate growth primary phosphates in association with occur during the pegmatite formation other Mn-bearing phosphates and concurrently with silicate hureaulite. Chemical analyses revealed crystallization, both from parental extreme Mn-rich compositions near to pegmatite magma. It is supported by in eosphorite end-member. Its formation Boqueirão, where primary phosphates can be attributed to different processes identified are triphylite, lithiophilite, than those related to the sarcopside, triplite, amblygonite, and formation/crystallization of the sicklerite. The latter formed from Li- pegmatite. Whiteite and jahnsite occur leaching alteration of lithiophilite- as yellow crystals filling veinlets inside triphylite and considered a primary previous phosphates. Under phase according to Corbella and microscope, they show high Melgarejo (1990). Subsequently to birefringence and typical polysynthetic pegmatite consolidation, late Na- twinned. Fe-rich supergenic phosphates metasomatism stage is expressed by late such as lipscombite, phosphosiderite albite units formed from metasomatic (Fig. 5d) and mitridatite (Fig. 5e) form exchange processes and by Na-rich fine grain patinas and crusts or phosphates crystallization such as aggregates above of precursor alluaudite and varulite deriving from

11 Estudos Geológicos vol. 24(2) 2014 www.ufpe.br/estudosgeologicos Sandra Amores Casals et al. primary triphylite-ferrisicklerite that they have been formed by the oxidation (Fransolet and Hatert, 2004; entrance of late hydrothermal or Roda-Robles et al., 2010; Hatert et al., supergenic fluids (Corbella and 2011). Secondary hureaulite, eosphorite, Melgarejo, 1990) and they do not keep whiteite, jahnsite, phosphosiderite, any relationship with pegmatite lipscombite, mitridatite and consolidation. serrabrancaite are found as veins and The abundance of phosphate porosity infillings, patinas or crusts. minerals demonstrate that the parental They may have crystallized by pegmatite magma was enriched in P but percolating meteoric waters at depth or depleted in other volatiles like F, by an aqueous fluid remaining after expressed by absence of F-rich mineral pegmatite consolidation producing a such as fluorite or topaz and it would widespread hydrothermal alteration of also explain triplite and amblygonite primary phosphates. scarcity observed in Cap de Creus pegmatite field (Corbella and Evolution of pegmatite Melgarejo, 1990). Hence, high P activity of pegmatite magma is The study of geochemical ratios in represented by scarcity of Li-bearing major minerals may provide an silicate (Černý and Ercit, 2005). approximation of pegmatite evolution Ferromagnesian silicates such as schorl degree. The most used ratios are and almandine prevail in the outer zones Mn/(Mn+Fe) in primary phosphates and of Boqueirão. Their ubiquity is a garnet, Li-Rb-Cs in feldspars and characteristic proxy of low evolved muscovite or Hf/Zr in zircon (London, magmas (London, 2008) in conjunction 2008), all increasing when fractionation with green alkali-poor beryl suggesting process advances. In spite of the high Fe contents in pegmatitic melt presence of abundant Mn-poor (Gonçalves, 2008). Low content of Hf triphylite, Boqueirão primary analysed in zircon correspond to low phosphates show Mn enrichment as Hf/Zr ratio also indicative of low degree observed by constant Mn/(Mn+Fe) of pegmatite evolution (Černý et al., values around 0.70 which suggests 1997; London, 2008). Nevertheless, the slight evolution of early pegmatite occurrences of beryl and scarce Ta-Nb magma. Sarcopside intergrowth inside minerals suggest that Boqueirão Mn-triphylite has similar Fe content pegmatite has enough degree of suggesting its primary origin. However, evolution to belong to beryl-columbite- primary lamellae texture can be phosphate subtype, according to Černý absolutely overprinted due to secondary and Ercit (2005). Consequently, it has phosphate alteration. It was studied in economical potential and metallogenic detail by Roda et al. (2004) and Hatert interest. et al. (2007) in the Cañada pegmatite. Lithiophilite – triphylite Mn/(Mn+Fe) Acknowledgements ratio remains constant in ferrisicklerite This research was supported by SGR- – sicklerite replacements but also in 444 project of the Generalitat de metasomatic alkaline phosphates as Catalunya. alluaudite and varulite. This behaviour suggests that early subsolidus stages REFERENCES after pegmatite crystallization and albitization process would be partially Baumgartner R., Romer, R., Moritz, R., closed. Mn/(Mn+Fe) ratio in secondary Sallet, R., Chiaradia, M., 2006. phosphates is not constant pointing out Columbite – Tantalite – Bearing

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granitic pegmatites from de Española de Mineralogía, 13: Seridó Belt, Northeastern Brazil: 169–182. Genetic constraints from U–Pb Fontan, F. 1976. Les phosphates des dating and Pb isotopes. The pegmatites de la región de Canadian Mineralogist, 44: 69– Crozant (Creuse). Bulletin de la 86. Société française de minéralogie, Beurlen, H., Da Silva, M.R.R, Thomas, 99: 318–321. R., Soares, D.R, Olivier, P. 2008. Fransolet, A.M, Hatert, F. 2004. Nb-Ta-(Ti-Sn) oxide mineral Petrographic evidence for primary chemistry as tracer of rare element hagendorfite in an unusual granitic pegmatite fractionation in assemblage of phosphate the Borborema Province, minerals, Kibingo granitic Northeastern Brazil. Mineralium pegmatite, Rwanda. The Canadian Deposita, 43: 207–228. Mineralogist, 42: 697–704. Beurlen, H., Barreto, S., Martin, R., Gonçalves, A.O. 2008. Caracterización Melgarejo, J.C., da Silva, M.R.R., mineralógica, geoquímica y Souza Neto, J.A. 2009. The petrogenética de las pegmatitas Borborema pegmatite province, graníticas de Giraúl, Namibe, NE-Brazil. Revisited. Estudos Angola. PhD Thesis by Geológicos, 19: 62–66. Universidad de Zaragoza. 445 p. Cameron, E.N., Jahns, R.H, McNair, Hatert, F., Roda-Robles, E., Keller, P., A.H., Page, L.R. 1949. Internal Fontan, F., Fransolet, A.M. 2007. Structure of Granitic Pegmatites. Petrogenetic significance of the Economic Geologist, Monograph triphylite + sarcopside intergrowth 2. in granitic pegmatites: an Černý, P. 1991a. Rare–element granitic experimental investigation of the pegmatites. Part I: anatomy and Li(Fe,Mn)(PO4) – (Fe,Mn)3(PO4)2 internal evolution of pegmatite system. Granitic Pegmatites: The deposits. Geoscience Canada, 18: state of the Art – International 49–67. Symposium, Porto, Portugal. Cerný, P., Alfonso, P., Melgarejo, J.C. Hatert, F., Ottolini, L., Schmid- 1997. Pegmatites granítiques. In: Beurmann, P. (2011): Melgarejo, J.C. (Eds): Atles Experimental investigation of the d’Associacions Minerals en alluaudite + triphylite assemblage, Làmina Prima. Edicions de la and development of the Na-in- Universitat de Barcelona, triphylite geothermometer: Barcelona (ISBN: 84-89829-24-1) application to natural pegmatite p. 129–152. phosphates. Contributions to Černý, P., Ercit, T.S. 2005. The Mineralogy and Petrology, 161: classification of granitic 531–546. pegmatites revisited. The Lima, E.S. 1986. Metamorphism and Canadian Mineralogist, 43: 2005– Tectonic Evolution in the Seridó 2026. Region, Northeastern Brazil. PhD Corbella. M, Melgarejo, J.C. 1990. Thesis University of California. Características y distribución de London, D. 2008. Pegmatites. The los fosfatos de las pegmatitas Canadian Mineralogist, Special graníticas de la Península del Cap Publication, 10 p. 347. de Creus (Pirineo Oriental London, D., Burt, D.M. 1982. catalán). Boletín de la Sociedad Alteration of spodumene, montebrasite and lithiophilite in

13 Estudos Geológicos vol. 24(2) 2014 www.ufpe.br/estudosgeologicos Sandra Amores Casals et al.

pegmatite of the White Picacho Ferreira. A.C.M. 2008. District, Arizona. The American Compositional variation of Mineralogist 67: 97–113. tourmaline group minerals in the Moore, P.B. 1982. Pegmatite minerals Borborema Pegmatitic Province, of P(V) and B(III). In Černý Northeastern Brazil. The (Eds): Granitic pegmatites in Canadian Mineralogist, 46: 1097– science and industry. MAC Short 1116. Course Handbook, 8: 267–291. Van Schmus, W.R., Brito Neves, B.B., Roda, E., Pesquera, A., Fontan, F., Hackspacher, P., Fetter, A.H., Keller, P. 2004. Phosphate Dantas, E.L., Babinski, M. 2003. mineral associations in the The Seridó Group of NE Brazil, a Cañada pegmatites (Salamanca, late Neoproterozoic preto syn- Spain): Paragenetic relationships, collisional basin in West chemical compositions, and Gondwana: insights from implications for pegmatite SHRIMP U–Pb detrital zircon evolution. The American ages and Sm–Nd crustal residence Mineralogist, 89: 110–125. (TDM) ages. Precambrian Roda-Robles, E., Vieira, R., Pesquera, Research, 127: 287–327. A., Lima, A. 2010. Chemical Witzke, T., Wegner, R., Doering, T., variations and significance of Pöllmann, H., Schuckmann, W. phosphates from the Fregeneda- 2000. Serrabrancaite, Almendra pegmatite field, Central MnPO4·H2O, a new mineral from Iberian Zone (Spain and the Alto Serra Branca Pegmatite, Portugal). Mineralogy and Pedra Lavrada, Paraiba, Brazil. Petrology, 100: 24–34. The American Mineralogist, 85: Soares, D.R., Beurlen. H., De Brito 847–849. Barreto. S, Da Silva. M.R.R,

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