DOCSLIB.ORG

597 the Wodginite Group. I. Structural

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
597 the Wodginite Group. I. Structural 597 Canadion Mineralogist Vol. 30, pp.597-6rr (1992) THE WODGINITE GROUP. I. STRUCTURAL CRYSTALLOGRAPHY T. SCOTT ERCIT Mineral SciencesSection, Canadian Museum of Nature, Ottawa,Ontario KIP 6P4 FRANK C. HAWTHORNE ANNPETRIERNY Departmentof GeologicotSciences, (lniversity of Manitoba, Winnipeg,Manitoba R3T 2N2 ABSTRACT Four new crystal-saugturerefinements have been done on wodginite-groupminerals. Two partially orderedsamples were usedin single-crystalexperiments, one, tantalian, the other, ferroan. The ferroan samplewas heatedto induce order, and its structure was-re-refined. In addition to the single-crystalexperiments, a Rietveld refinement from powdlr-diffracrion dara was done on a fully ordered lithiowodginite. Refinementsof the partially ordered samples ihow that they are structurally intermediate io wodginite and ixiolite, and that heating under conventional conditions of l000oC foi 16 hours inducls full wodginite-typecation order. In terms of both individual and meanbondJengths' data for Li-rich samplesdeviate signific;ntb fiom establishedtrends for Li-poorer samplesin a martnerconsistent with disorder of Li off the central7 position. Schemesof cation order for potential derivativesof ixiolite have been evaluatedfor cells up to four times ihe volume of the ixiolite cell = size of the wodginite cell). For full .4BC2O3 cation order, four most-probableschenies of order result. Three of these involve a doubled cell; one involves a quadrupledcell, relative tb an ixiolite parent, Only the schemeof order with a quadrupledcell occursnaturally' l'.e., tire wodginite siructure; there is nothing in its schime of order to indicate why nature prefers it over the other three schemes;more sophisticatedcalculations of energyseem necessary. Keywords:crystal-structure refinement, wodginite gXoup,order-disorder, Rietveld method. SovINleIns Nous avonseffectu6 quatre nouveauxaffinements de la structurecristalline de min€rauxdu groupe de la wodginite. Deux de ceux-ci,partielliment ordonn6s,dont un esttantalifbre et l'autre, ferreux, ont 6t6utilisds pour desexpdriences sur cristal unique. L'€chantillon riche en fer a 6t6 chauffd pour promouvoir une,mise en ordre, et I'affinement de sa structure a 6t6 rdpdt6.En plus, nous avons effectu6 I'affinement d'un €chantillon de lithiowodginite completement ordonn6 ,u, poodr" par la mfihode de Rietveld. Les affinementsdes dchantillonspartiell€ment ordonn6s montrent qu'ils sont ,iro.torul"-.nt interm6diaires i la wodginite et a I'ixiolite, et qu'un chauffage sous conditions conventionnellesde 1000"C pour 16 heuresmdne i une mise en ordre compldtedes cations selon le modble de la wodginite. D'aprbs les longueursdes liaisons individuelles et moyennes,les donn6espour les dchantillonsriches en Li ddvientde faConimportante des tendances {tablies pour ceuxqui sont plus pauvresen Li, et concordentavec I'hypothBse qu,il y a d6sbrdredu Li par rapport A la position centrale/. Nout avons dvaludles sch€masde mise en ordre des cationspour les d€riv6spotentleti de I'idolite pour desmailles jusqu'i quatre fois le volume de la maille de l'ixiolite' c'est-i-dire, de la maille de la wodginite. Poui le modbled'une miie en ordre compl&tedes cations selon,4BC2Os,-il en r6sulte quatre sch€masplausibles. Trois de ceux-ci impliquent une maille doubl€e; un schdmarequlgrt une maille quadrupl6e,par rappon i ia maille de l'ixiolite. Seul le sch6made mise en ordre de la maille quadrupldese retrouve dans la natuie, souJforme de wodginite. Rien n'explique le ddveloppementpreferentiel de ce sch6ma,plutOt que les trois autres. Des calculsplus sophiitiqu{s de l'€nergie des structuressemblent indiquds pour expliquer ce point. (Traduit par la Rddaction) Mots-cl6s: affinemenl de la structure cristalline, groupe de la wodginite, ordre-d€sordre, m6thode de Rietveld. INtnooucrton proposed a model for the wodginite $tructure; however, only subcell reflections were used, for the The crystal structureof wodginite, MnSnTazOs, resulting in an erroneous space-group was first recognizedas a superstructureof ixiolite, structure. Grice (1973)attempted a full refinement (Ta,Sn,Mn)Oz,by Nickel et al. (1963)on the basis of the structure (space Eroup C2/c). He showed of X-ray powder-diffraction data. Elphick (1972) that there are three cationic sites in the wodginite 598 THE CANADIAN MINERALOGIST structure, and that all cations are in octahedral one-half of the octahedralinterstices at eachlevel coordination; the octahedra form e-pbO-like in the close-packedarray ofanions. There are three zig-zag chains yia sharing of polyhedron .ig.t. cationic sites, denotedhere as A, B and C. The A Graham & Thornber (1974)published a refinement and I siteslie at the samelevel in the closest-pack- of the wodginite structure in the spacegroup Cc, ing, whereasthe C siteslie at a different level;these which resultedin four cationic sites,two of which layers alternate along X. All coordination show incomplete order among cation occupants. polyhedra link via edge-sharingto form a-PbO2- Fergusonet al. (1976)re-investigated the structure like zig-zag chains along Z. Chains are intercon- of wodginite and showedthat the results of Grice nectedby corner-sharinglinkages between levels of (1973)and Graham & Thornber (1974) arein error the closest-packedlayering. The.4 and I polyhedra owing to incorrect choicesof origin; C2,/c, not Cc, alternate along the zig-zag chains of their level; is the correct space-group.Gatehouse et al. (1976) adjacentlevels necessarily consist only of chainsof showedthat the compound M-LiTa3Oris isostruc- C polyhedra. tural with wodginite, and obtained the same Ideally, the .4 site contains Mn, the B site solution of the structure as Fergusonet al. (1976). contains Sn, and the C site contains Ta, resulting A later Rietveld refinement of the M-LiTarO, in the ideal formula MnSnTa2O6(Z : 4) for structure using neutron powder-diffraction dita wodginite. Fergusonet al. (1976)showed thar Ta (Santoro et al, 1977)Iocated the Li atom, which can be disorderedover the .B and C sites;however, Gatehousee/ al. (1976)could not find in their X-ray as disorder between the B and C sites does not experiment. modify the space-groupsymmetry, this behavior Polyhedral representations of the wodginite can only be easilydetected by examiningresults of structure are shown in Figures I and 2. Oxygen chemicalanalyses for Ta-overstuffedcompositions. atoms form approximatelyhexagonally close-pack- Powder-diffraction experimentsshow that some ed layers perpendicular to X. Cations occupy membersof the wodginite group have X-ray-dif- a b Flc. I . The structureof ideal wodginiteprojected along X; (a) the layer of.4, .Boctahedra; (b) the layer of C octahedra. ,a (Mn) octahedra are hatch-stippled,I (Sn) octahedraare denselystippled, and C (Ta) octahedraare lightly stippled. STRUCTURAL CRYSTALLOGRAPHY OF THE WODCINITE CROUP 599 a Ftc. 2. The wodginite structureprojected along Z; the ag-zag chainsof the structure are perpendicularto the plane of the page. Shadingis as in Figure l. fraction properties intermediate to those of with the wodginite structure, and does not wodginite and ixiolite (as proposedby Lahti 1982) contradict the terminology describedabove. or wodginite and wolframite [as proposed by In companion papers (Ercit et al. l992a,b), we Maksimova & Khvostova (1970)and Polyakov & outline variations in the chemistryand structureof group, Cherepivskaya(1981)1. The model involving ixiolite what we now recognizeto be the wodginite goal presentpaper is to investigatethe implies disorder over all cationic sites; the model The of the properties of wodginite-groupminerals, involving wolframite implies disorderonly over the structural with emphasison order-disorder relationships. A and B sites. In principle, it should be relatively easyto differentiatebetween the two modelson the EXPERIMENTAL basisof site occupanciesderived from crystal-struc- refinements.To avoid any confusionregarding ture Single-cry s t qI diffr actio n order-disorder phenomena in wodginite-group minerals,we shall usethe following nomenclature. Two samplesof wodginite-groupminerals were For samples with diffraction properties fully examinedby single-crystalX-ray diffraction; both compatiblewith the wodginite structure,we usethe are paftially ordered, one intermediatein composi- term (fully) ordered; for samples with diffraction tion betweenwodginite and lithiowodginite (sample properties intermediateto those of the wodginite CX-l: Coosa Co., Alabama), the other inter- structure and those of some substructure (e.9., mediate in composition between wodginite and ixiolite, wolframite), we use the term partially ferrowodginite (sample A-17: Ankole, Uganda). ordered. Disorder of Ta over the B and C sitesis SampleCX-l was donatedby E.E. Foord (U.S. herereferred to as Ta disorder; it is fully compatible Geological Surve$, and was describedas having 600 THE CANADIAN MINERALOGIST diffraction properties intermediate betweenthose IAALE A CHEMICAL COMPOSMONS OF WODGINTTE€NOUP MINEFAI.S USED IN STNUCTUFE REFINEMENG} of wodginite and wolframite (E.E. Foord, pers. Wodglnte Parlsly Lruriq F€tl@ comm.). Ords€d wodglnno Wodghne SampleA-17 was investigatedin Ercit el Wodghls al. (1992a); it shows diffraction properties inter- p@14 (cx.0 (rsE-76) W1n w (vJt%) 0.0 02. 121 0.6 mediate betweenthose of wodginite and ixiolite. MnO 10.7 7.7 4.6 6.1 FeO 0.0 23 0.0 4.7 The observed morphology indicates that both SnO o,7 FolCa 0.8 za 0.1 1.8 crystalsare sector-twinned,with Yas the twin axis. na 1.4 L5 In both cases, Z!O2 1'5 a fragment from one
Load more

Recommended publications
  • The Wodginite Group. Iii. Classification and New Species
    633 Canadian Mineralogist Vol. 30, pp. 633-638(1992) THE WODGINITE GROUP. III. CLASSIFICATION AND NEW SPECIES T. SCOTT ERCITI, PETRIERNY eNp FRANK C, HAWTHORNE Deportmentof GeologicalSciences, University of Manitoba, Winnipeg,Manitoba R3T 2N2 ABSTRACT The minerals constituting the wodginite group are isostructural oxides, with the generalformula ABC2Oy (Z = 4);A = Mn2*, Fd*, Li, E B : Sn4*, Ti, Fe3*, Ta;C : Ta, Nb. A classificationsystembased onthe chemistry of the .,4-and B-cationsites has been devised; it useschemical modifiers in conjunctionwith the root name"wodginite". Wodginite itself has the generalformula MnSnTa2Os;two new membersof the wodginite group are charactedzed here:-ferrowodginite, F/+SnTa2Os and titanowoiginite, MnTiTa2Os. Ferrowodginite occurs as 0.01- to- 0.2-mm inclusionsin cassiteritefrom a granitic pegmatitenear Sukula, southwestemFinland. It is dark brown to black' has a dark brown streak, vitreous luster, is optically anisotropic with all n>2, and is nonfluorescent.The calculated density is 7.02 g/cm3; it is brittle, H 5%, without cleavage;it has an irregular fracture. The averagechemical composition(wt. Vo)is: MnO 2.8, FeO 9.3, Fe2O31.9, TiO2 4.3, SnO210.1, Nb2O5 14.8, Ta2O5 56.3, total 99.4.The strongestfivelines in the X-ray powderpauein-are:4.16('50),'2.g7(Aq,2.55(30i, 2.493(40\ {nd 1.a55(30)A. fne unit-cell parametersare o 9.415(7),b 11.442(6),c 5.103(4)A, B 90.8(l)', V 549.'7(6)Ar, spacegroup A/c. Titanowodginiteoccurs as euhedral,diamond-shaped crystals up to I cm acrossat the Tanco pegmatite,Bernic Lake, Manitoba.
    [Show full text]
  • The Crystal Ghemistry of Complex Niobium and Tantalum Oxides Ll. Composition and Structure of Wodginite
    American Mineralogist, Volume 59, pages 1040-1044, 1974 TheCrystal Ghemistry of ComplexNiobium and Tantalum Oxides ll. Compositionand Structure of Wodginite J. Gnermu, axo M. R. TnonNsnn Diaision of Mineralogy, CSIRO, Floreat Park, Iilestern Australia, 6014 Abstract The structure of wodginite (non-centrosymmetric monoclinic space group Cc; ideal formula, MnXtX[lao,, where site Xg contains 5-valent ions (and all the niobium) and the average valency of cations in site X, is 4) was determined by film methods to be an ordered form of tho ixiolite structure. The a and D cell edges and angle B increase with manganesb content, whereas c remains constant for wodginites from five localities in Western Australia. Composition and Lattice Parameters from Wodgina, hand picked from a homogeneous The charasteristicsof the mineral wodginite were region of a polished section.Electron probe analysis clearly describedby Nickel, Rowland, and McAdam and powderX-ray diffraction (Hiigg Guinier focussing (1963) for samplesof the mineral from Wodgina, camera) gave the cell dimensibnsand composition Australia, and Bernic Lake, Manitoba. The s,truc- usedin the calculationsshown in Table l. Data were ture was not fully defined, and the efiect of com- collectedphotographically along two axes([010] and positionalvariations on the st,ructurecould not there- Ul2l) using a Nonius Integrating Weissenberg fore be discussed. camera, equiinclination geometry,and CuKa radia- Table 1 shows the compositions and lattice tion. After the applicationof Lorenz and polarization parametersof wodginitesfrom five localitiesin West- corrections, these two sets of data were inter-cor- ern Australia and the averageparameters quoted by related, and symmetrically similar reflections were Grice, eerny and Ferguson (1972) fbr the wod- averagedto give 555 independentobservations.
    [Show full text]
  • First U.S. Occurrence of Wodginite from Powhatan County, Virginia
    American Mineralogist, Volume 69, pages 807-809, 1984 First U.S. occurrenceof wodginitefrom PowhatanCounty, Virginia MrcHeel A. WIse eNo Pnrn er,nNf Department of Earth Sciences, University of Manitoba Winnipeg, Manitoba R3T 2N2 Canada Abstract Wodginite occurs as black subhedral grains in the Be, Nb-Ta, Sn bearing Herbb #2 pegmatite in Powhatan County, Virginia. The wodginite is associatedwith amazonite and topaz in the intermediate zone of the pegmatite. Other Nb-Ta-bearing minerals found associated with wodginite are cassiterite, in part as inclusions in wodginite, and par- tially ordered man6ianocolumbite.The Herbb wodginite is compositionally similar to previ- ously studied wodginitesand has an averageformula (Mnz.aoFe?.1sb+.or(Snz.oqTirrcTaost Fd.14)x.8e(Ta7.ozNbos8)>8.0oOrz.The average unit cell dimensions ate a 9.471(2), b tt.43t(2),c 5.108(l)A, p90"47'(t),v 553.1(l)43. Introduction ite), quartz and muscovite are the dominant minerals present. Beryl, topaz, columbite-tantalite,wodginite, A black mineral, at first believed to be columbite- cassiterite,and minor spessartinealso occur in the peg- tantalite, was collected by the first author from the Herbb matite, mainly in the clayey decomposition products. #2 pegmatite in Powhatan County, central Virginia. Wodginite is found scatteredthroughout the kaolinized Griffitts et al. (1953) noted "small lustrous tabular to feldsparof the intermediatezones. Veinlets of wodginite equant crystals of columbite-tantalite"in albitized por- also occur near perthitic amazonitebodies and to a lesser tions of this pegmatite,a speciesalso quotedby Jahnset eitent are also associatedwith topaz. al. (1952).Recent examination of Nb,Ta-bearingminerals from this locality has led to the identification of the rare Physical properties Mn,Sn,Ta-oxidemineral, wodginite.
    [Show full text]
  • Crystallization Processes and Solubility of Columbite-(Mn), Tantalite-(Mn), Microlite, Pyrochlore, Wodginite and Titanowodginite in Highly Fluxed Haplogranitic Melts
    Western University Scholarship@Western Scholarship@Western Electronic Thesis and Dissertation Repository 3-12-2018 10:30 AM Crystallization processes and solubility of columbite-(Mn), tantalite-(Mn), microlite, pyrochlore, wodginite and titanowodginite in highly fluxed haplogranitic melts Alysha G. McNeil The University of Western Ontario Supervisor Linnen, Robert L. The University of Western Ontario Co-Supervisor Flemming, Roberta L. The University of Western Ontario Graduate Program in Geology A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Alysha G. McNeil 2018 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Earth Sciences Commons Recommended Citation McNeil, Alysha G., "Crystallization processes and solubility of columbite-(Mn), tantalite-(Mn), microlite, pyrochlore, wodginite and titanowodginite in highly fluxed haplogranitic melts" (2018). Electronic Thesis and Dissertation Repository. 5261. https://ir.lib.uwo.ca/etd/5261 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Abstract Niobium and tantalum are critical metals that are necessary for many modern technologies such as smartphones, computers, cars, etc. Ore minerals of niobium and tantalum are typically associated with pegmatites and include columbite, tantalite, wodginite, titanowodginite, microlite and pyrochlore. Solubility and crystallization mechanisms of columbite-(Mn) and tantalite-(Mn) have been extensively studied in haplogranitic melts, with little research into other ore minerals. A new method of synthesis has been developed enabling synthesis of columbite-(Mn), tantalite-(Mn), hafnon, zircon, and titanowodginite for use in experiments at temperatures ≤ 850 °C and 200 MPa, conditions attainable by cold seal pressure vessels.
    [Show full text]
  • Exsolution of Zirconian-Hafnian Wodginite from Manganoan-Tantalian Cassiterite, Annie Claim #3 Granitic Pegmatite, Southeastern Manitoba, Canada
    685 The Canadian Mineralogist Vol. 38, pp. 685-694 (2000) EXSOLUTION OF ZIRCONIAN-HAFNIAN WODGINITE FROM MANGANOAN-TANTALIAN CASSITERITE, ANNIE CLAIM #3 GRANITIC PEGMATITE, SOUTHEASTERN MANITOBA, CANADA MORGAN MASAU, PETR CERNˇ Y´ § AND RON CHAPMAN Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada ABSTRACT Primary (Mn,Fe,Ta,Nb)-bearing cassiterite with ≤0.21 wt.% ZrO2 and ≤0.05 wt.% HfO2 crystallized during the consolidation of the Archean Annie Claim #3 zoned, lepidolite-subtype granitic pegmatite, southeastern Manitoba, in amounts increasing from the outer to the inner pegmatite zones. Rare inclusions of tantalite and ferrotapiolite originated from transient local saturation in these phases. Sparse early cassiterite from the outer intermediate zone is rather rich in substituting elements and in part Fe- dominant, whereas the more abundant late cassiterite from the lepidolite core is strongly Mn-dominant and poor in the substituents. Exsolution in the primary cassiterite generated granular zirconian-hafnian ferrowodginite and wodginite enclosed in veinlets of substituent-depleted cassiterite. The Fe/Mn and Nb/Ta values of the wodginite phases mimic those of the primary cassiterite across the pegmatite zones, and Zr/Hf perceptibly decreases from the outer zones inward. Maximum contents of ZrO2 and HfO2 (5.98 and 1.59 wt.%, respectively; 0.31 Zr and 0.04 Hf apfu) are the highest so far encountered in wodginite-group minerals. These maxima characterize wodginite exsolved from early cassiterite; the levels drop off in wodginite exsolved in late cassiterite. Instead, hafnian zircon intergrown with abundant thorian coffinite becomes abundant in the lepidolite core, indicating a transition of Zr + Hf from octahedral sites in the oxide minerals to the much more common 8-fold coordination in the orthosilicate; this shift implies a transition from relatively alkaline to more acidic conditions.
    [Show full text]
  • Cation Distribution in Partially Ordered Columbite from the Kings Mountain
    American Mineralogist, Volume 76, pages 1897-1904, 1991 Cation distribution in partially ordered columbite from the Kings Mountain pegmatite,North Carolina M,qnc WnNGrn.TrroNr.ts Anrvrnnusrnn I-aboratorium fiir chemischeund mineralogischeKristallographie, Universitit Bern, Freiestrasse3, CH-3012 Bern, Switzerland Cnlllns A. Gnrcnn BayerischesForschungsinstitut {iir experimentelle Geochemie und Geophysik, Universitdt Bayreuth, Postfach IOl25l, D-8580 Bayreuth, Germany ABSTRAcT Two columbite samples,space group Pbcn, with a : 14.233,b : 5.724,c : 5.104 A, Z: 4 and a: 14.221,b : 5.727,c : 5.102A, of similar chemistry(average composition FeourMno.roTi005Nb.TaorOu)but from different rock types of the Kings Mountain peg- matite, North Carolina, were investigated. One columbite specimen (NCP5) originates from a primary spodumene pegmatite, the other (NCPI) from a rock composed mainly of sugaryalbite formed by subsequenthydrothermal activity. Single-crystalX-ray structure refinements indicate that both columbite samplesshow strong disorder between (Nb,Ta) and (Fe,Mn) on octahedral A and B positions. This is in agreementwith a Mdssbauer spectrum (NCP5), which was fitted with two doublets characteristicof two distinct t61Fe2+ sites. Both samples show strong chemical zoning with respect to Nb and Ta, but weak zoning of Fe and Mn. The similar chemical composition and cation ordering indicate that columbite in both rocks is formed by the same process.Late hydrothermal alteration of the original spodumenepegmatite did not affect the composition of the earlier crystallized columbite. The primary columbite (NCP5) shows slightly stronger disorder of two- and five-valent cations than columbite (NCPI) found in the hydrothermally altered part of the pegmatite. INrnonucrroN some samplesreveal a wodginite pattern (Khvostova and Maximova, 1969),whereas others yield a columbite pat- Minerals of the columbite-tantalite group have the gen- tern (Nickel et al., 1963b).
    [Show full text]
  • Alkali Oxide-Tantalum Oxide and Alkali Oxide-Niobium Oxide Ionic Conductors
    NASA CR-1 34599 .Aft ALKALI OXIDE-TANTALUM OXIDE AND ALKALI OXIDE-NIOBIUM OXIDE IONIC CONDUCTORS by R. S. Roth, H. S. Parker, W. S. Brower and D. Minor prepared for NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CONTRACT C-29933C NATIONAL BUREAU OF STANDARDS WASHINGTON, D.C. 20234 1 1 Report No. 2. Government Accession No. 3. Recioient's Catalog No. CR-134599 NBSIR 7L-LL0 A Tit I a t r-v /-4 Ci it^titla H. 1 iiie ana oudiiti6 5. Report Date ALKALI OXIDE-TANTALUM OXIDE AND ALKALI OXIDE-NIOBIUM OXIDE April 1974 IONIC CONDUCTORS 6. Performing Organisation Code 7. Author(s) 8. Performing Organization Report No. R. S. Roth, H. s. Parker, W. S. Brower and D. Minor 10. Work Unit No. 9. Performing Organization Name and Address YOK 5650 National Bureau of Standards 11. Contract or Grant No. Washington, D.C. 20234 C-29933C 13. Type of Report and Period Covered Final Report 12. Sponsoring Agency Name and Address October 1972 - October 1973 National Aeronautics and Space Administration Lewis Research Center 14. Sponsoring Agency Code 21000 Brookpark Road Cleveland, Ohio 44135 15. Supplementary Notes Project Manager: Patricia O'Donnell 16. Abstract A search was made for new cationic conducting phases in alkali-tantalate and niobate systems. The phase equilibrium diagrams were constructed for the six binary systems ^'^2°5"-^^^'^°3' Nb^O^-NaNbO^, Nb^O^-KNbO^, Ta^O^-NaTaO^ , Ta^O^-LiTaO^ and Ta^O^-KTaO^. Various other binary and ternary systems were also examined. Pellets of nineteen phases were evaulated <by the sponsoring agency) by dielectric loss measurements.
    [Show full text]
  • The Wodginite Group. I. Structural Crystallography
    597 Canadian Mineralogist Vol. 30, pp. 597-611 (1992) THE WODGINITE GROUP. I. STRUCTURAL CRYSTALLOGRAPHY T. SCOTT ERCIT Mineral Sciences Section, Canadian Museum of Nature, Ottawa, Ontario KIP 6P4 FRANK C. HAWTHORNE AND PETR CERNY Department of Geological Sciences, University of Ma nitoba, Winnipeg, Ma nitoba R3T 2N2 ABSTRACT Four new crystal-structure refinements have been done on wodginite-group minerals. Two partially ordered samples were used in single-crystal experiments, one, tantalian, the other, ferroan. The ferroan sample was heated to induce order, and its structure was re-refined. In addition to the single-crystal experiments, a Rietveld refinement from powder-diffraction data was done on a fully ordered lithiowodginite. Refinements of the partially ordered samples show that they are structurally intermediate to wodginite and ixiolite, and that heating under conventional conditions of 1000°C for 16 hours induces full wodginite-type cation order. In terms of both individual and mean bond-lengths, data for Li-rich samples deviate significantly from established trends for Li-poorer samples in a manner consistent with disorder of Li off the central A position. Schemes of cation order for potential derivatives of ixiolite have been evaluated for cells up to four times the volume of the ixiolite cell = size of the wodginite cell). For full ABC208 cation order, four most-probable schemes of order result. Three of these involve a doubled cell; one involves a quadrupled cell, relative to an ixiolite parent. Only the scheme of order with a quadrupled cell occurs naturally, i. e. , the wodginite structure; there is nothing in its scheme of order to indicate why nature prefers it over the other three schemes; more sophisticated calculations of energy seem necessary.
    [Show full text]
  • Evolution of Nb,Ta-Oxide Mineralization in Rare-Metal Pegmatites of the East Sayan Belt, Siberia, Russia
    Granitic Pegmatites: The State of the Art – International Symposium. 06th – 12th May 2007, Porto, Portugal. Evolution of Nb,Ta-oxide mineralization in rare-metal pegmatites of the East Sayan belt, Siberia, Russia V. M. MAKAGON Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk, Russia, [email protected] ABSTRACT Variations of Nb,Ta-oxide mineral composition were studied in rare-metal pegmatites of the East Sayan belt. Nb,Ta-oxide mineralization is different in spodumene and petalite pegmatites. First of them contain mainly minerals of columbite group of different composition. Petalite pegmatites have broad scope of Nb,Ta-oxide minerals, in which Ta predominate. Keywords: Rare-metal pegmatites, Nb,Ta-oxide minerals. albite pegmatite. Sections of quartz-lepidolite complex INTRODUCTION and muscovite aggregate are observed. The East Sayan belt of rare-metal pegmatites is located CHEMYSTRY OF NB,TA-OXIDE MINERALS in the south-western part of the Siberian platform. It includes the largest in Russia Goltsovoye and Electron microprobe analyses of the Nb,Ta-oxide Vishnyakovskoye pegmatite deposits of rare metals. minerals are carried out. The Nb,Ta-oxide minerals are common in these pegmatites, however their chemical composition is not Columbite group. Nb,Ta-oxides of columbite group enough well studied. In the light of new data this (Fe,Mn)(Nb,Ta)2O6 in veins of spodumene pegmatites research examines evolution of the Nb-Ta mineral mainly include ferrocolumbite, ferrotantalite, chemical composition. manganocolumbite and manganotantalite. Minerals of this group from differentiated spodumene pegmatites RARE-METAL PEGMATITES form trend of fractionation from ferrocolumbite of outer pegmatite body zone to manganocolumbite and then to The East Sayan belt includes several pegmatite fields.
    [Show full text]
  • Contributions to the Chemistry of Tapiolite Manganotapiolite, a New Mineral
    CONTRIBUTIONS TO THE CHEMISTRY OF TAPIOLITE MANGANOTAPIOLITE, A NEW MINERAL SEPPO I. LAHTI, BO JOHANSON and MARJATTA VIRKKUNEN LAHTI, SEPPO I.; JOHANSON, BO and VIRKKUNEN, MARJATTA 1983: Contributions to the chemistry of tapiolite - manganotapiolite, a new mineral. Bull. Geol. Soc. Finland 55, 2, 101-109. Microprobe determinations and X-ray diffraction studies of tapiolite specimens from the granitic pegmatites of the Eräjärvi area, in Orivesi, southern Finland, revealed a new manganese- dominant analogue of tapiolite. A small crystal, 1.5 mm long and 0.5 mm thick, from a narrow lithium pegmatite dyke shows some parts richer in Mn than Fe. The name manganotapiolite is used for this Mn-dominant member and ferrotapiolite for the common Fe- dominant member of the tapiolite group. The tapiolite crystal studied is prismatic, showing poorly devel- oped {100} faces. Manganotapiolite is dark brown, strongly pleochroic from yellowish brown to reddish brown, but thicker fragments are opaque. In reflected light the colour is grey with a weak bireflectance changing from light brownish grey to grey. Internal reflections are strong with red brown colour. The reflectance values measured in air are: 16.0-15.7 (470 nm), 14.7-14.1 (546 nm), 15.0-14.8 (589 nm), 15.1-14.6 (650 nm), and in oil: 4.5-4.0 (470 nm), 3.9-3.4 (546 nm), 4.3-3.8 (589 nm), 4.3-3.8 (650 nm). Density (calc.) is 7.72 g/cm3 and VHN (100 g load) 711. Micro probe analyses on five points of one manganese-rich part gave: FeO 6.4, 6.2, 3.7, 3.9 and 3.2; MnO 6.7, 7.7, 8.6, 9.7 and 10.2; CaO 0.4, 0.2, 0.6, 0.2 and 0.4; Ta20r78.1, 77.6, 78.6, 79.8 and 76.3; Nb20* 7.1, 7.6, 7.2, 6.7 and 8.5; Ti02 0.1, 0.1, 0.0, 0.0 and 0.0; SnOr 1.0, 1.2, 1.3, 1.0 and 1.0; Sb2Oa 0.0, 0.0, 0.0, 0.0 and 0.1; Total 99.8, 100.6, 100.1, 101.4 and 99.7 wt.
    [Show full text]
  • The Grystal Strugtures of Tantalite, Ixiolite And
    Canadian Mineralogist Vol. 14 pp. 5tl&549 (1976) THE GRYSTALSTRUGTURES OF TANTALITE,IXIOLITE AND WODGINITEFNOM BERNICLAKE, MANITOBA I. TANTALITEAND IXIOLITE J. D. GRICE*, R. B. FERGUSON AND F. C. HAWTHORNE Deparlment ol Earth Sciences,UniversiA of Manitoba, Winnipeg, Manitoba R3T 2N2 Assra.ec"r B(Ta)-0, 2.01(3)& e[es concordent chacung avec la somme des rayons ionrques, 2.19 et 2.fi)4, res- The crystal structures of matrganotantalite and pectivement. La somme des valences de liaison ixiolite from the Tanco pegmatite, Bernic Lake, (Pauling) qui aboutissent aux atomes d'oxyglne Manitoba have been refined using MoKo radiation O(l), O(2) et O(3) est peu pr6cise (2, lVz 2Yz u.v., and 3-dimensional 4-circle diffractometer data to respectivement), mais lorsqu'on ti€nt compte de la final R. values of 8.4Vo atd 8.97o respectiveb. distorsion des longueurs dans l'octaBdre (celui de B Tantalite:orthorbonhie Pbcn, a |4.4L3(3),, 5.760(I), en particulier) en consid6rant la valence de liaison c 5.0s4(1)4, Z-4\ABrosl-4[(Mne.r7Tin.62Fe!+q.s1 comme inversement proportionnelle I la 5" puis- Sne.6)(fa6.sNbo."")rOul. The structure of Stur- sance de la distance cation-oxygdne (Pyatenko 1973), divant (1930) is confirmed. The mean octahedral les atomes d'oxygdne regoivent 2.04, 1.99 et 1.97 l(MnlO distance is 2.18(4) and BCIa)-O is u.v., respectivement. 2.01(3)A, both in close agreement with the rele- L'ixiolite est orthorhombique Pbcn, a 4.785(2) va[t radii sums, 2,19 and 2.00A respectively.
    [Show full text]
  • Niobium and Tantalum
    Niobium and Tantalum Chapter M of Critical Mineral Resources of the United States—Economic and Environmental Geology and Prospects for Future Supply Figure M4. Professional Paper 1802–M U.S. Department of the Interior U.S. Geological Survey Periodic Table of Elements 1A 8A 1 2 hydrogen helium 1.008 2A 3A 4A 5A 6A 7A 4.003 3 4 5 6 7 8 9 10 lithium beryllium boron carbon nitrogen oxygen fluorine neon 6.94 9.012 10.81 12.01 14.01 16.00 19.00 20.18 11 12 13 14 15 16 17 18 sodium magnesium aluminum silicon phosphorus sulfur chlorine argon 22.99 24.31 3B 4B 5B 6B 7B 8B 11B 12B 26.98 28.09 30.97 32.06 35.45 39.95 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39.10 40.08 44.96 47.88 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.39 69.72 72.64 74.92 78.96 79.90 83.79 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 85.47 87.62 88.91 91.22 92.91 95.96 (98) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3 55 56 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 cesium barium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon 132.9 137.3 178.5 180.9 183.9 186.2 190.2 192.2 195.1 197.0 200.5 204.4 207.2 209.0 (209) (210)(222) 87 88 104 105 106 107 108 109 110 111 112
    [Show full text]