DOCSLIB.ORG

Phosphate Fractionation in Pegmatites of Pedra Da Moura Ii Claim – Ponte Da Barca – Portugal

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Phosphate Fractionation in Pegmatites of Pedra Da Moura Ii Claim – Ponte Da Barca – Portugal View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Universidade do Minho: RepositoriUM PHOSPHATE FRACTIONATION IN PEGMATITES OF PEDRA DA MOURA II CLAIM – PONTE DA BARCA – PORTUGAL Leal Gomes,C. Azevedo, A. Lopes Nunes, J. Dias, P.A. Universidade do Minho – CIG-R – Escola de Ciências – Gualtar-4710-057 Braga, Portugal Keywords – mingling corridor, inner granite pegamtite, triphylite, oligonite, fractionation INTRODUCTION bodies located along the most leucogranitic stripe of an inner granite, mixing-mingling The Pedra da Moura pegmatite group corridor, which was established between - in the proximity of Ponte da Barca village, two distinctive facies of two-mica granites Northern Portugal (Fig.1) - is a rosary like – one coarse grained, essentially biotitic alignment of irregular shaped pegmatite and the other porphyroid also biotitic. Pedra da Moura II claim 1 2 BRAGA 3 4 5 6 OPORTO N AVEIRO 20 km Fig. 1 – Location of the studied pegmatite group within the Pedra da Moura II claim. Symbols: 1- major tectonic lineaments; 2 – Post- tectonic granites in relation to D3 Variscan folding phase; 3 - D3 late tectonic granitoids related with ductile shear; 4 - D3 syntectonic granitoids related with ductile shear; 5 – two-mica granites sin - tectonic in relation to D3; 6 – restitic-two mica granites and migmatites. 172 Estudos Geológicos v. 19 (2), 2009 C. Leal Gomes, et al. Transition zones towards the hosting and graphic pegmatite with coarse, radial granites are enriched in white mica, garnet to plumous mica intergrowths (Fig 2). Fig. 2 – Current asymmetrical transition between the two-mica granites, the leucogranite and the pegmatites. KF – microcline; Qz – quartz; AP – undifferentiated apatite mass. Geological setting is complicated trajectory, 46º=>134º, parallel to the by the near presence of a Silurian magma ascent - planar arrangement of metasedimentary roof pendent and K-feldspar is 130º/90º. At the enclave several fl ux-oriented swarms of xenoliths swarms, ascent lineation is mainly, suggesting the proximity of the cupola of 66º=>116º. The general orientation of the the magma chamber. Magmatic lineation mingling corridor, 132º, reveals a sense of (fl ux lineation) is marked by megafeldspar injection to the NW (Fig. 3). Estudos Geológicos v. 19 (2), 2009 173 PHOSPHATE FRACTIONATION IN PEGMATITES OF PEDRA DA MOURA II CLAIM PONTE DA BARCA – PORTUGAL SSE SE N NNW 20M NW pegmatite inner units - quartz core magmatic flux lineation in garnet (Mn-almandine) + cordierite leucogranite pegmatite outer units - border and intermediate zones magmatic flux lineation in xenolith-rich leucogranite coarse grained two mica granite melanocratic restictic schlieren coarse grained, porphyroid two mica granite essentially biotitic megafeldspar flux lineation joint or fault surface Figure 3 – Structure and anatomy of Pedra da Moura pegmatite group (inner granite), situated along a mixing-mingling magma corridor - 3d perspective bloc with the approximate location referred in fi g. 1; 1999 is the reference for the image present in fi g.4 and obtained in the year 1999. Pegmatite bodies are heterogeneous, PRIMARY ACCESSORY MINERALS asymmetrically zoned and contact gradually with the different types of The mineral assemblages were granites, thus, the cinematic interpretation characterized and its suites and stable is compatible with a late-Variscan members discriminated by X-Ray emplacement and “in situ” gradual and diffractometry. Paragenetic relations were direct fractionation from the host stripe of established using geometric criteria and transitional leucogranite. the interpretation of crystal intergrowths. These pegmatites are quartz-rich. The major accessory minerals are At the zones with the coarser crystals, beryl, Nb-Ta-Ti oxides and mainly, primary inside de graphic boundary, quartz cores phosphates - such as F-apatite, isokite, frequently occupy more than 2/3 of the triplite-zwiezelite, triphylite-litiophylite, volume and the gemmy variety, pink eosphorite, or berlinite – as well as, several quartz, may be predominant, and typically sulphides, sulphosalts and carbonates, located at the periphery of the core. White mainly oligonite. Hypothetically and hyaline varieties are nuclear. Albite they correspond to early stages of the and orthoclase to microcline feldspar paragenetic evolution, predating the occur in equal quantities and phosphate centripetal completeness of primary assemblages can accomplish as much as fractionation. They are located mainly at 10% modal volume of coarse pegmatite. transition between inner intermediate zone 174 Estudos Geológicos v. 19 (2), 2009 C. Leal Gomes, et al. and quartz core and so possibly represent an PARAGENETIC EVOLUTION equilibrium episode of depuration of excess phosphorous, materialized as a mineralogical The more stable primary phosphates threshold and assuming the form of a occur at the younger, sometimes miarolitic, structural front, coherent with the model of hydrothermal stages of quartz core formation “in situ” crystallization (fi g. 4). – berlinite (occasionally with pink gem Northwest pegmatites are more quality) and a late population of zoned fractionated (high Li in mica and lower K/ F-apatite are typical of this stage. Rb in microcline) and have more complex In the other cases, each one of the phosphate assemblages: triphylite- primary phosphates can generate a specifi c litiophylite > triplite-zwiezelite> F-apatite> and independent evolutionary sequence eosphorite> withlockite > reddingite - depending on peculiar combinations and TRIPHYLITE-LITIOPHYILITE SUITE. succession of deuteric to meteoric conditions, Sulphide minerals are rare. Typical multiple however, liquidus-subsolvus to subsolidus phosphate composite aggregates include and meteoric evolution are much more primarily and sequentially equilibrated: complex when affecting trifi lite-litiofi lite. triphylite-litiophylite => wolfeite => In liquidus state triphylite-litiophylite withlockite => F-apatite => eosphorite evolves to wolfeite and in liquidus to => reddingite =>oligonite => triplite – subsolvus conditions evolves to eosphorite, zwiezelite and F-apatite => wolfeite. sometimes collected as an interstitial phase The southeast bodies have less in triple junctions; in subsolvus to subsolidus diversifi ed assemblages and typically the same mineral tends towards a fairfi eldite sulphides are associated with phosphates + vivianite ± hureaulite (subsolidus, and quartz. F-apatite + pyrite ± sphalerite hydrothermal evolution and triphylite + arsenopyrite + quartz occur in great aureole formation) ± sicklerite assemblage; masses at the border of the quartz core. in subsolidus it evolves to heterosite and/or Besides apatite, triplite-zwiezelite and the purpurite. paragenetically dependent isockite are the In subsolvus conditions F-apatite can main phosphate phases determining the evolve to wolfeite and in subsolidus can TRIPLITE-ZWIEZELITE SUITE: triplite – evolve to OH-apatite and later to CO3-OH- zwiezelite => isockite => F-apatite + pyrite apatite. => clorite (chamosite) + F-apatite ± pyrite, Frequently the change products are arsenopyrite, chalcopyrite, sphalerite. The maintained inside the original contour of the Pb – Bi – Ag sulphides and sulphossalts pristine crystal. This means that the cardinal coexist with sphalerite and quartz graphic minerals of the paragenesis (mainly silicates) intergrowths at the close vicinity of F-apatite persist in equilibrium. + pyrite intergrowths and include matildite, In what concerns hydrothermal cosalite, eskimoite, bismuthinite and alteration several phosphates can be affected galenobismuthite. From a spatial point of simultaneously for example when a given view, and from SSE to NNW, it seems to later fracture affects different mineral exist a trend of magma/fl uid evolution and species. In this case evolutionary suites can crystallization in the sense of Li and Mn mix, resulting several textures, which can be enrichment at the phosphate assemblages. ascribed to individualized phenomena: This trend accompanies the sense of igneous A) Corrosion - explains some mass dislocation, which is deduced from cavernous cavities and box-work like geometric and cinematic analysis. textures circumscribed to earlier volumes Estudos Geológicos v. 19 (2), 2009 175 PHOSPHATE FRACTIONATION IN PEGMATITES OF PEDRA DA MOURA II CLAIM PONTE DA BARCA – PORTUGAL of primary crystals; in these conditions Later hydrothermal to supergenic the departure volume of initial crystal alteration promotes a fi rst diverging is reduced and phosphate anion as well evolution, which produces corrosion cavities as Ca2+, Fe3+, Fe2+, Mn2+ are removed; with re-equilibrated walls and ion leaching. the resulting contaminated fl uids can re- The latest reactions are convergent and precipitate second generation phosphates promote ion fi xation and replenishment of inside the corrosion cavities. B) “In situ” the vacuoles. transformation – corresponds mainly Vacuolar like textures are enhanced to hydration processes with volume in supergenic state of evolution and enhancement, which can generate irradiating include a large set of minerals specially sets of ruptures at the surrounding minerals; when the hostage is triphylite-litiophylite: the fractures can be replenished with late sicklerite, heterosite-purpurite, frondelite- generation phosphates. Sometimes in almost rockbridgeite and barbosalite. Vacuole closed systems it is possible to identify replenishment includes deposition of phase transitions by direct hydration.
Load more

Recommended publications
  • L. Jahnsite, Segelerite, and Robertsite, Three New Transition Metal Phosphate Species Ll. Redefinition of Overite, an Lsotype Of
    American Mineralogist, Volume 59, pages 48-59, 1974 l. Jahnsite,Segelerite, and Robertsite,Three New TransitionMetal PhosphateSpecies ll. Redefinitionof Overite,an lsotypeof Segelerite Pnur BnnN Moone Thc Departmcntof the GeophysicalSciences, The Uniuersityof Chicago, Chicago,Illinois 60637 ilt. lsotypyof Robertsite,Mitridatite, and Arseniosiderite Peur BmaN Moonp With Two Chemical Analvsesbv JUN Iro Deryrtrnent of GeologicalSciences, Haraard Uniuersity, Cambridge, Massrchusetts 02 I 38 Abstract Three new species,-jahnsite, segelerite, and robertsite,-occur in moderate abundance as late stage products in corroded triphylite-heterosite-ferrisicklerite-rockbridgeite masses, associated with leucophosphite,hureaulite, collinsite, laueite, etc.Type specimensare from the Tip Top pegmatite, near Custer, South Dakota. Jahnsite, caMn2+Mgr(Hro)aFe3+z(oH)rlPC)oln,a 14.94(2),b 7.14(l), c 9.93(1)A, p 110.16(8)", P2/a, Z : 2, specific gavity 2.71, biaxial (-), 2V large, e 1.640,p 1.658,t l.6lo, occurs abundantly as striated short to long prismatic crystals, nut brown, yellow, yellow-orange to greenish-yellowin color.Formsarec{001},a{100},il2oll, jl2}ll,ft[iol],/tolll,nt110],andz{itt}. Segeierite,CaMg(HrO)rFes+(OH)[POdz, a 14.826{5),b 18.751(4),c7.30(1)A, Pcca, Z : 8, specific gaavity2.67, biaxial (-), 2Ylarge,a 1.618,p 1.6t5, z 1.650,occurs sparingly as striated yellow'green prismaticcrystals, with c[00], r{010}, nlll0l and qll2l } with perfect {010} cleavage'It is the Feg+-analogueofoverite; a restudy on type overite revealsthe spacegroup Pcca and the ideal formula CaMg(HrO)dl(OH)[POr]r. Robertsite,carMna+r(oH)o(Hro){Ponlr, a 17.36,b lg.53,c 11.30A,p 96.0o,A2/a, Z: 8, specific gravity3.l,T,cleavage[l00] good,biaxial(-) a1.775,8 *t - 1.82,2V-8o,pleochroismextreme (Y, Z = deep reddish brown; 17 : pale reddish-pink), @curs as fibrous massesand small wedge- shapedcrystals showing c[001 f , a{1@}, qt031}.
    [Show full text]
  • Geology of the Hugo Pegmatite Keystone, South Dakota
    Geology of the Hugo Pegmatite Keystone, South Dakota GEOLOGICAL SURVEY PROFESSIONAL PAPER 297-B Geology of the Hugo Pegmatite Keystone, South Dakota By J. J. NORTON, L. R. PAGE, and D. A. BROBST PEGMATITES AND OTHER PRECAMBRIAN ROCKS IN THE SOUTHERN BLACK HILLS GEOLOGICAL SURVEY PROFESSIONAL PAPER 297-P A detailed structural and petrologic study of a pegmatite containing seven zones and two replacement bodies UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1962 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25, D.C. CONTENTS Page Page Abstract.. _ ________________________________________ 49 Mineral distribution and paragenesis of the entire Introduction. ______________________________________ 49 pegmatite_ _ ______________________-___---------_ 96 General geology. ___________________________________ 52 Comparison of the zonal sequence with that in other Metamorphic rocks_ ____________________________ 52 pegmatites. ______________________________________ 97 Roy and Monte Carlo pegmatites.- _ __---__-______ 53 Replacement features-______________________________ 100 Structure __________________________________________ 53 Review of the evidence for replacement in pegma­ Pegmatite units ____________________________________ 53 tites __ _____________________________________ 100 Zone 1 : Albite-quartz-musco vite pegmatite ________ 56 Replacement in the Hugo pegmatite.____-_____-_- 102
    [Show full text]
  • Mineral Processing
    Mineral Processing Foundations of theory and practice of minerallurgy 1st English edition JAN DRZYMALA, C. Eng., Ph.D., D.Sc. Member of the Polish Mineral Processing Society Wroclaw University of Technology 2007 Translation: J. Drzymala, A. Swatek Reviewer: A. Luszczkiewicz Published as supplied by the author ©Copyright by Jan Drzymala, Wroclaw 2007 Computer typesetting: Danuta Szyszka Cover design: Danuta Szyszka Cover photo: Sebastian Bożek Oficyna Wydawnicza Politechniki Wrocławskiej Wybrzeze Wyspianskiego 27 50-370 Wroclaw Any part of this publication can be used in any form by any means provided that the usage is acknowledged by the citation: Drzymala, J., Mineral Processing, Foundations of theory and practice of minerallurgy, Oficyna Wydawnicza PWr., 2007, www.ig.pwr.wroc.pl/minproc ISBN 978-83-7493-362-9 Contents Introduction ....................................................................................................................9 Part I Introduction to mineral processing .....................................................................13 1. From the Big Bang to mineral processing................................................................14 1.1. The formation of matter ...................................................................................14 1.2. Elementary particles.........................................................................................16 1.3. Molecules .........................................................................................................18 1.4. Solids................................................................................................................19
    [Show full text]
  • List of New Mineral Names: with an Index of Authors
    415 A (fifth) list of new mineral names: with an index of authors. 1 By L. J. S~v.scs~, M.A., F.G.S. Assistant in the ~Iineral Department of the,Brltish Museum. [Communicated June 7, 1910.] Aglaurito. R. Handmann, 1907. Zeita. Min. Geol. Stuttgart, col. i, p. 78. Orthoc]ase-felspar with a fine blue reflection forming a constituent of quartz-porphyry (Aglauritporphyr) from Teplitz, Bohemia. Named from ~,Xavpo~ ---- ~Xa&, bright. Alaito. K. A. ~Yenadkevi~, 1909. BuU. Acad. Sci. Saint-P6tersbourg, ser. 6, col. iii, p. 185 (A~am~s). Hydrate~l vanadic oxide, V205. H~O, forming blood=red, mossy growths with silky lustre. Founi] with turanite (q. v.) in thct neighbourhood of the Alai Mountains, Russian Central Asia. Alamosite. C. Palaehe and H. E. Merwin, 1909. Amer. Journ. Sci., ser. 4, col. xxvii, p. 899; Zeits. Kryst. Min., col. xlvi, p. 518. Lead recta-silicate, PbSiOs, occurring as snow-white, radially fibrous masses. Crystals are monoclinic, though apparently not isom0rphous with wol]astonite. From Alamos, Sonora, Mexico. Prepared artificially by S. Hilpert and P. Weiller, Ber. Deutsch. Chem. Ges., 1909, col. xlii, p. 2969. Aloisiite. L. Colomba, 1908. Rend. B. Accad. Lincei, Roma, set. 5, col. xvii, sere. 2, p. 233. A hydrated sub-silicate of calcium, ferrous iron, magnesium, sodium, and hydrogen, (R pp, R',), SiO,, occurring in an amorphous condition, intimately mixed with oalcinm carbonate, in a palagonite-tuff at Fort Portal, Uganda. Named in honour of H.R.H. Prince Luigi Amedeo of Savoy, Duke of Abruzzi. Aloisius or Aloysius is a Latin form of Luigi or I~ewis.
    [Show full text]
  • The Secondary Phosphate Minerals from Conselheiro Pena Pegmatite District (Minas Gerais, Brazil): Substitutions of Triphylite and Montebrasite Scholz, R.; Chaves, M
    The secondary phosphate minerals from Conselheiro Pena Pegmatite District (Minas Gerais, Brazil): substitutions of triphylite and montebrasite Scholz, R.; Chaves, M. L. S. C.; Belotti, F. M.; Filho, M. Cândido; Filho, L. Autor(es): A. D. Menezes; Silveira, C. Publicado por: Imprensa da Universidade de Coimbra URL persistente: URI:http://hdl.handle.net/10316.2/31441 DOI: DOI:http://dx.doi.org/10.14195/978-989-26-0534-0_27 Accessed : 2-Oct-2021 20:21:49 A navegação consulta e descarregamento dos títulos inseridos nas Bibliotecas Digitais UC Digitalis, UC Pombalina e UC Impactum, pressupõem a aceitação plena e sem reservas dos Termos e Condições de Uso destas Bibliotecas Digitais, disponíveis em https://digitalis.uc.pt/pt-pt/termos. Conforme exposto nos referidos Termos e Condições de Uso, o descarregamento de títulos de acesso restrito requer uma licença válida de autorização devendo o utilizador aceder ao(s) documento(s) a partir de um endereço de IP da instituição detentora da supramencionada licença. Ao utilizador é apenas permitido o descarregamento para uso pessoal, pelo que o emprego do(s) título(s) descarregado(s) para outro fim, designadamente comercial, carece de autorização do respetivo autor ou editor da obra. Na medida em que todas as obras da UC Digitalis se encontram protegidas pelo Código do Direito de Autor e Direitos Conexos e demais legislação aplicável, toda a cópia, parcial ou total, deste documento, nos casos em que é legalmente admitida, deverá conter ou fazer-se acompanhar por este aviso. pombalina.uc.pt digitalis.uc.pt 9 789892 605111 Série Documentos A presente obra reúne um conjunto de contribuições apresentadas no I Congresso Imprensa da Universidade de Coimbra Internacional de Geociências na CPLP, que decorreu de 14 a 16 de maio de 2012 no Coimbra University Press Auditório da Reitoria da Universidade de Coimbra.
    [Show full text]
  • 38Th RMS Program Notes
    E.fu\wsoil 'og PROGRAM Thursday Evening, April 14, 2011 PM 4:00-6:00 Cocktails and Snacks – Hospitality Suite 400 (4th Floor) 6:00-7:45 Dinner – Baxter’s 8:00-9:15 THE GUALTERONI COLLECTION: A TIME CAPSULE FROM A CENTURY AGO – Dr. Renato Pagano In 1950, the honorary curator of the Museum of Natural History in Genoa first introduced Dr. Renato Pagano to mineral collecting as a Boy Scout. He has never looked back. He holds a doctorate in electrical engineering and had a distinguished career as an Italian industrialist. His passion for minerals has produced a collection of more than 13,000 specimens, with both systematic and aesthetic subcollections. His wife Adriana shares his passion for minerals and is his partner in collecting and curating. An excellent profile of Renato, Adriana, and their many collections appeared earlier this year in Mineralogical Record (42:41-52). Tonight Dr. Pagano will talk about an historic mineral collection assembled between 1861 and 1908 and recently acquired intact by the Museum of Natural History of Milan. We most warmly welcome Dr. Renato Pagano back to the speakers’ podium. 9:15 Cocktails and snacks in the Hospitality Suite on the 4th floor will be available throughout the rest of the evening. Dealers’ rooms will be open at this time. All of the dealers are located on the 4th floor. Friday Morning, April 15, 2011 AM 9:00 Announcements 9:15-10:15 CRACKING THE CODE OF PHLOGOPITE DEPOSITS IN QUÉBEC (PARKER MINE), MADAGASCAR (AMPANDANDRAVA) AND RUSSIA (KOVDOR) – Dr. Robert F. Martin Robert François Martin is an emeritus professor of geology at McGill University in Montreal.
    [Show full text]
  • NEW MINERALS It Is Proposed Hereafter to Indicate In.A General Way the Classification of All New Minerals Recoided in This Department
    JOURNAL MINERALOGICAL SOCIETY OF AMENICA 63 Dr. Kunz then spoke of the various city localities and the minerals found therein. He stated that the East Side, from 37 to 110 St., probably afforded the most specimens. The various tunnels and their minerals were spoken of. Capt. Miller called attention to the fine collection of Brooklyn Drift Minerals and Rocks in the collection of the Long Island Historical Society. Ife abo mentioned the occurrence of monazite and xenotime crystals, on the Speedway,Harlem River. Dr. Kunz emphasizedthe irnportance of complete records being kept of all finds. Tnou,q,s L Mrr,r,nn, SecretaryPro, Tem. NEW MINERALS It is proposed hereafter to indicate in.a general way the classification of all new minerals recoided in this department. Subdivision will be first into "families," of which nine may be recognized,as listed in the January number (Am. Min.6 (1), 12,1921). Eachfamilywillbe separatedinto "subfamilies " based on special features of composition. This arrangement is tentative and open to modification, and criticism of it will be welcome, [Eo.] FAMILY 2. SULFIDES, ETC. SosreMrr,v 3. Doust,u suLFrDEs oF METALSAND sEMr-METAr,s. I'LTRABASITE V. Rosrcxf and J. Srnnse-Btinu. Ultrabasit, ein neues Mineral aus Freiberg in Sachsen. (Ultrabasite, a new mineral from Freiberg, Saxony). Rozpr.Eeslcd Ako,il. Prag,25, No. 45, 1916;Z. Krgst. Min., 55,43H39, 1920, Neun: From its extremely basic chemical composition. Pnrsrcar, Pnopnnrrus Color black, somewhat grayish; luster metallic; streak black; cleavage none; fracture scaly, with somewhat greasy luster on the surface. H. : 5; sp. gr.
    [Show full text]
  • New Mineral Names*,†
    American Mineralogist, Volume 106, pages 1360–1364, 2021 New Mineral Names*,† Dmitriy I. Belakovskiy1, and Yulia Uvarova2 1Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18 korp. 2, Moscow 119071, Russia 2CSIRO Mineral Resources, ARRC, 26 Dick Perry Avenue, Kensington, Western Australia 6151, Australia In this issue This New Mineral Names has entries for 11 new species, including 7 minerals of jahnsite group: jahnsite- (NaMnMg), jahnsite-(NaMnMn), jahnsite-(CaMnZn), jahnsite-(MnMnFe), jahnsite-(MnMnMg), jahnsite- (MnMnZn), and whiteite-(MnMnMg); lasnierite, manganflurlite (with a new data for flurlite), tewite, and wumuite. Lasnierite* the LA-ICP-MS analysis, but their concentrations were below detec- B. Rondeau, B. Devouard, D. Jacob, P. Roussel, N. Stephant, C. Boulet, tion limits. The empirical formula is (Ca0.59Sr0.37)Ʃ0.96(Mg1.42Fe0.54)Ʃ1.96 V. Mollé, M. Corre, E. Fritsch, C. Ferraris, and G.C. Parodi (2019) Al0.87(P2.99Si0.01)Ʃ3.00(O11.41F0.59)Ʃ12 based on 12 (O+F) pfu. The strongest lines of the calculated powder X-ray diffraction pattern are [dcalc Å (I%calc; Lasnierite, (Ca,Sr)(Mg,Fe)2Al(PO4)3, a new phosphate accompany- ing lazulite from Mt. Ibity, Madagascar: an example of structural hkl)]: 4.421 (83; 040), 3.802 (63, 131), 3.706 (100; 022), 3.305 (99; 141), characterization from dynamic refinement of precession electron 2.890 (90; 211), 2.781 (69; 221), 2.772 (67; 061), 2.601 (97; 023). It diffraction data on submicrometer sample. European Journal of was not possible to perform powder nor single-crystal X-ray diffraction Mineralogy, 31(2), 379–388.
    [Show full text]
  • 259 XLL-Chemical Researches on Some New and Rare Corn.Ish
    259 XLL-Chemical Researches on some new and rare Corn.ish Miwrals. By A. H. CHURCH,M.A., Professor of Chemistry, Royal Agricultural College, Cirencester. I. Hydrated Cerous Phosphate. THEhydrous phosphate which forms the subject of the present commnnication, occurs as a thin crust closely investing a quartzose matrix. This crust is made up of very minute crystals, generally occurring in fan-like aggregations of single rows of prisms. The faces of union of these groups are parallel to the larger lateral prismatic planes. Occasionally the structure is almost columnar, or in radiating groups, presenting a drusy surface and a general appearance somewhat resemlding that of mavellite. The mode of attachment of the crystals is such that only one of the end-faces of the prisms can be studied fully. It would appear that the crystals belong to the oblique system, and are prismatically deve- loped forms. The end-face, 001, presents the aspect of an unmodi- fied rhomboid ; occasionally, however, its diagonally opposite acute angles are replaced. Whether the appearances then presented by the crystal are due to a truncation of the solid acute angle, OF to a bevelling of the acute prismatic edge, it is difficult to say, owing to the microscopic siee of the crystals, and their parallel mode of aggregation. The plane of cleavage most easily obtained is parallel to the end- face 001; this cleavage is very perfect. Other cleavages are obtainable; one parallel to the plane previously referred to as replaciug the acute solid angles or acute prismatic edges of the crystal, the other parallel to the larger lateral prismatic planes.
    [Show full text]
  • Geology of the Pegmatites and Associated Rocks of Maine
    DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, DIRECTOR BULLETIN 445 GEOLOGY OF THE PEGMATITES AND ASSOCIATED ROCKS OF MAINE INCLUDING FELDSPAR, QUARTZ, MICA, AND GEM DEPOSITS BY EDSON S. BASTIN WASHINGTON GOVERNMENT PRINTING OFFICE 1911 CONTENTS. Introduction.............................................................. 9 Definition of pegmatite...................................................... 10 Geographic distribution.................................................... 10 Geology.................................................................. 10 Bordering rocks....................................................... 10 Pegmatites in foliated rocks........................................ 11 General statement............................................ 11 Sedimentary foliates........................................... 11 Igneous foliates.....".......................................... 12 Pegmatites in massive granites.................................... 13 'Age.................................................................. 15 General character..................................................... 15 Mineral and chemical composition................................. 15 Mineral constituents.......................................... 15 Relative proportions of minerals............................... 18 Quartzose phases. ..............................^............. 18 Fluidal cavities............................................... 19 Sodium and lithium phases................................... 20 Muscovite
    [Show full text]
  • Triphylite Li(Fe , Mn )PO4 C 2001-2005 Mineral Data Publishing, Version 1
    2+ 2+ Triphylite Li(Fe , Mn )PO4 c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Orthorhombic. Point Group: 2/m 2/m 2/m. Crystals rare, typically prismatic, with large {011}, {100}, {010}, {021}, {120}, several other forms. Commonly subhedral, to 6.5 m, cleavable, compact, massive. Physical Properties: Cleavage: {100}, perfect; {010}, imperfect; {011}, interrupted. Fracture: Uneven to subconchoidal. Hardness = 4–5 D(meas.) = 3.50–3.58 D(calc.) = 3.562 Optical Properties: Transparent to translucent. Color: Bluish gray to greenish gray; brownish to black where altered. Streak: White to grayish white. Luster: Vitreous to subresinous. Optical Class: Biaxial (+). Orientation: X = a or c; Y = c or b; Z = b or a. Dispersion: r<v, strong. α = 1.675–1.694 β = 1.684–1.695 γ = 1.685–1.700 2V(meas.) = 0◦–55◦ Cell Data: Space Group: P mnb. a = 6.0285(6) b = 10.3586(9) c = 4.7031(3) Z = 4 X-ray Powder Pattern: Palermo #1 mine, New Hampshire, USA. 3.008 (100), 2.525 (81), 4.277 (76), 3.487 (70), 5.175 (34), 2.781 (34), 3.923 (26) Chemistry: (1) (2) P2O5 44.76 45.11 Fe2O3 1.07 FeO 30.05 22.84 MnO 12.40 22.55 MgO 0.72 CaO 0.34 Li2O 8.33 9.50 H2O 0.25 insol. 1.55 Total 99.47 100.00 (1) “Central Asia”, Russia. (2) Li(Fe, Mn)PO4 with Mn:Fe = 1:1. Mineral Group: Forms a series with lithiophilite. Occurrence: The most abundant primary phosphate in complex zoned granite pegmatites.
    [Show full text]
  • Roscherite-Group Minerals from Brazil
    ■ ■ Roscherite-Group Minerals yÜÉÅ UÜté|Ä Daniel Atencio* and José M.V. Coutinho Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080 – São Paulo, SP, Brazil. *e-mail: [email protected] Luiz A.D. Menezes Filho Rua Esmeralda, 534 – Prado, 30410-080 - Belo Horizonte, MG, Brazil. INTRODUCTION The three currently recognized members of the roscherite group are roscherite (Mn2+ analog), zanazziite (Mg analog), and greifensteinite (Fe2+ analog). These three species are monoclinic but triclinic variations have also been described (Fanfani et al. 1977, Leavens et al. 1990). Previously reported Brazilian occurrences of roscherite-group minerals include the Sapucaia mine, Lavra do Ênio, Alto Serra Branca, the Córrego Frio pegmatite, the Lavra da Ilha pegmatite, and the Pirineus mine. We report here the following three additional occurrences: the Pomarolli farm, Lavra do Telírio, and São Geraldo do Baixio. We also note the existence of a fourth member of the group, an as-yet undescribed monoclinic Fe3+-dominant species with higher refractive indices. The formulas are as follows, including a possible formula for the new species: Roscherite Ca2Mn5Be4(PO4)6(OH)4 • 6H2O Zanazziite Ca2Mg5Be4(PO4)6(OH)4 • 6H2O 2+ Greifensteinite Ca2Fe 5Be4(PO4)6(OH)4 • 6H2O 3+ 3+ Fe -dominant Ca2Fe 3.33Be4(PO4)6(OH)4 • 6H2O ■ 1 ■ Axis, Volume 1, Number 6 (2005) www.MineralogicalRecord.com ■ ■ THE OCCURRENCES Alto Serra Branca, Pedra Lavrada, Paraíba Unanalyzed “roscherite” was reported by Farias and Silva (1986) from the Alto Serra Branca granite pegmatite, 11 km southwest of Pedra Lavrada, Paraíba state, associated with several other phosphates including triphylite, lithiophilite, amblygonite, tavorite, zwieselite, rockbridgeite, huréaulite, phosphosiderite, variscite, cyrilovite and mitridatite.
    [Show full text]