DOCSLIB.ORG

4Utpo3so UM-P-88/125

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
4Utpo3so UM-P-88/125 4utpo3So UM-P-88/125 The Incorporation of Transuranic Elements in Titanatc Nuclear Waste Ceramics by Hj. Matzke1, B.W. Seatonberry2, I.L.F. Ray1, H. Thiele1, H. Trisoglio1, C.T. Walker1, and T.J. White3'4'5 1 Commission of the European Communities, Joint Research Centre, i Karlsruhe Establishment, ' \ 'I European Institute for Transuranium Elements, Postfach 2340, D-7500 Karlsruhe, Federal Republic of Germany. 2 Advanced Materials Program, Australian Nuclear Science and Technology Organization, Private Mail Bag No. 1, Menai, N.S.W., 2234, Australia. 3 National Advanced Materials Analytical Centre, School of Physics, The University of Melbourne, Parkville, Vic, 3052, Australia. Supported by the Australian Natio-al Energy Research, Development and Demonstration Programme. 4 Member, The American Ceramic Society 5 Author to whom correspondence whould oe addressed 2 The incorporation of actinide elements and their rare earth element analogues in titanatc nuclear waste forms are reviewed. New partitioning data are presented for three waste forms contining Purex waste simulant in combination with either NpC^, PuC>2 or An^Oo. The greater proportion of transuranics partition between perovskitc and ztrconoiite, while some americium may enter loveringite. Autoradiography revealed clusters of plutonium atoms which have been interpreted as unrcacted dioxide or scsquioxide. It is concluded that the solid state behavior of transaranic elements in titanate waste forms is poorly understood; certainly inadequate to tailor a ceramic for the incorporation of fast breeder reactor wastes. A number of experiments are proposed that will provide an adequate, data base for the formulation and fabrication of transuranic-bearing jj [i waste forms. ' ' 1 ~> I. Introduction The potential of titanate-based ceramics as media for the solidification and stabilization of high level nuclear waste has been extensively documented. These studies have in the main been concerned with the formulation and preparation of the waste forms, optimization of their physical and chemical properties, and microstructural characterization. Significantly, the majority of this work has been conducted on material containing simulated (non-radioactive) waste. Considering ceramic waste forms have, on occasion, been promoted as superior to vitreous waste forms for the disposal of transuranic (TRU) rich fast breeder reactor (FBR) wastes,1 surprisingly little effort has been made to verify this assumption. , For titanate waste forms, the available evidence suggests that all the 'actinide (ACT) elements can be incorporated amongst perovskite and the zirconolite polytypes. However, there has been no rigorous investigation designed specifically to establish the solid solution limits of ACT elements in these phases nor their partitioning coefficients. In those cases where samples containing transuranic nuclides have been fabricated, the physical changes accompanying self-irradiation, rather than crystallochemical properties, have been emphasized. This paucity of solid state chemical data is now limiting discussion of the merits of TRU immobilization in titanate assemblages. In this paper, we review the literature describing the incorporation of ACT elements in titanate phases and present the results of a microstructural investigation of three titanate waste forms containing neptunium, plutonium and americium. Using this evidence we summarize the crystallochemical properties of the ACT elements and suggest a number of experiments which should be undertaken to optimize the design of a dedicated TRU waste form. 4 II. Previous Investigations TRU elements are often regarded as comparable to rare earth (RE) elements of similar ionic radii and valence (Table I), and many workers have used these non-active analogues to evaluate the characteristics of ACT species.2-3'4 Although much useful data can be collected in this way, care is required when a mixture of REs is involved to ensure that each is simultaneously in the correct oxidation state to simulate the TRU element of interest. For example, Ce + and Nd + could adequately simulate Np and Am respectively. However, under the reducing conditions used to fabricate titanate waste forms, cerium (as well as neodymium) is trivalent, thereby obviating the desired mimicry of solid state behavior.5»<>.7 An alternate experiment in which the waste form is fabricated under oxidizing conditions to stabilize tetravalent cerium is equally misleading, as trivalent titanium would not be formed. Since this species plays a key role in maintaining charge balance in many altervalent substitutions8 the partitioning of the TRU simulants would be different to that expected under actual fabrication conditions, and the proportions of radwaste bearing phases would alter.^ Therefore, in polyphase assemblages, where the simulation of two or more TRU elements is required, it is often impossible to design an appropriately controlled experiment. This complicates the correlation of properties of RE analogues with TRU elements and can limit the usefulness of this approach. It is, however, often practical to carry out simulation experiments using (nearly) single phase material and one RE analogue. A summary of relevant studies is given in Table II. (1) RE ind ACT Incorporation in Single Phase Ceramics Zirconolite Polytypes. Several studies have been made of the partitioning of trivalent REs into zirconolite polytypes.^ These phases which protypically have the formula CaZr^Oy,11 can employ two cation acceptor sites to accommodate REs; 3 3 8 a larger CaOg cube (volume = 21.3 A ) and smaller Zr07 polyhedron (15 A ). Rosscll concluded that small REs partition onto both sites, whereas the larger, lighter REs (e.g. Nd ) enter the calcium-site only.12 However, at the time of this work the polytypic nature of zirconolite was not recognized. A more recent study by Fielding et al.13 has shown that when zirconolite-2M is doped beyond 5 wt% neodymium it is impossible to prepare this polytype as single phase. Rather, it coexists with zirconolite-3T and another polytype with as yet lmdctermined crystal structure. The 2M polytype has neodymium partitioned strongly into the calcium- site whilst the 3T form exhibited equal part;,ioning of neodymium over both cation acceptor sites. Small RE elements (e.g. Yb ) do not stabilize zirconolite-3T and reside almost exclusively in the zirconium-site. Thorium, the largest ACT will partition into either the calcium- or zirconium- sites of the zirconolite polytypes in accordance with charge balance 1 A 4 + considerations.14 If no small ions suitable to replace titanium are present, Th will isomorphically replace Zr in zirconolite-2M. In the presence of Mg , Fe or Al thorium enters the calcium-site with the concommitant stabilization of zirconolite-3T. At higher levels, these coupled substitutions cause the formation of zirconolite-30.1^ Tetravalent uranium14 and plutonium16 have been examined individually as dopant species and both are reported as entering the zirconium-site. No data exists for neptunium, although it would be reasonable to assume that iis behavior would parallel that of uranium and plutonium. Of the trivalent ACTs, curium is believed to partition between the calcium- and zirconium-sites.17 The properties of trivalent plutonium and americium have not been examined. Pyrochlore. Unlike the zirconolite polytypes for which a rudimentary data base exists for the prediction of TRU partitioning, the other titanate phases which are usually considered as suitable immobilization matrices, viz. perovskite and pyrochlore, have received little attention. A recent examination of uranium incorporation in a calcium-rich betafite (pyrochlore) suggested that although the stoichiometry of this phase can be approximated to CaUTi20^, the Ca/U ratio is probably not unity.18 A plutonium analogue of nominal stoichiometry CaPuTi-O^ was prepared by Clinard et al.19 Similarity, cerium is reported as replacing zirconium to stabilize CaCeTi^O^ pyrochlore,20 although iti solid solubility with CaZrTi20^ has not been determined. 6 Perovskite. The only data relating to ACT partitioning in CaTiO* perovskite was presented by Rossouw et al.21 These workers found that about S at% uranium could enter the structure replacing calcium; it is believed that charge balance was achieved by the reduction of tetravalent titanium. The existence of the end- member CaThCK has been reported, but there is no evidence for extensive miscibility with CaTiO,.22 An attempt to synthesise CaPuO-, has been unsuccessful.23 Evans and Marples24 reported the synthesis of [Ca Q^PU 04] lT*l Ov however no chemical data was presented in support of this stoichiometry. (2) TRU Partitioning in Polyphase Assemblages In addition to studies of (predominantly) single phase systems a number of experiments have been devised to determine the partitioning of one or more TRU !? ! elements in polyphase assemblages resembling those of| projected waste forms (Table III). Angelini et al.25 prepared a four phase assemblage containing hollandite, perovskite, zirconolite (polytype unspecified) and pseudobrookite doped with plutonium, americium and curium. Using autoradiography they determined that all three TRU elements entered zirconolite and perovskite. However, they were unable to examine the valence of higher TRU cations, and the relevance of this experiment is unclear since the ceramic was prepared from the melt to promote grain growth. Consequently, elemental partitioning is likely to be different from that encountered
Load more

Recommended publications
  • Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization
    materials Review Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization Albina I. Orlova 1 and Michael I. Ojovan 2,3,* 1 Lobachevsky State University of Nizhny Novgorod, 23 Gagarina av., 603950 Nizhny Novgorod, Russian Federation 2 Department of Radiochemistry, Lomonosov Moscow State University, Moscow 119991, Russia 3 Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK * Correspondence: [email protected] Received: 31 May 2019; Accepted: 12 August 2019; Published: 19 August 2019 Abstract: Crystalline ceramics are intensively investigated as effective materials in various nuclear energy applications, such as inert matrix and accident tolerant fuels and nuclear waste immobilization. This paper presents an analysis of the current status of work in this field of material sciences. We have considered inorganic materials characterized by different structures, including simple oxides with fluorite structure, complex oxides (pyrochlore, murataite, zirconolite, perovskite, hollandite, garnet, crichtonite, freudenbergite, and P-pollucite), simple silicates (zircon/thorite/coffinite, titanite (sphen), britholite), framework silicates (zeolite, pollucite, nepheline /leucite, sodalite, cancrinite, micas structures), phosphates (monazite, xenotime, apatite, kosnarite (NZP), langbeinite, thorium phosphate diphosphate, struvite, meta-ankoleite), and aluminates with a magnetoplumbite structure. These materials can contain in their composition various cations in different combinations and ratios: Li–Cs, Tl, Ag, Be–Ba, Pb, Mn, Co, Ni, Cu, Cd, B, Al, Fe, Ga, Sc, Cr, V, Sb, Nb, Ta, La, Ce, rare-earth elements (REEs), Si, Ti, Zr, Hf, Sn, Bi, Nb, Th, U, Np, Pu, Am and Cm. They can be prepared in the form of powders, including nano-powders, as well as in form of monolith (bulk) ceramics.
    [Show full text]
  • Washington State Minerals Checklist
    Division of Geology and Earth Resources MS 47007; Olympia, WA 98504-7007 Washington State 360-902-1450; 360-902-1785 fax E-mail: [email protected] Website: http://www.dnr.wa.gov/geology Minerals Checklist Note: Mineral names in parentheses are the preferred species names. Compiled by Raymond Lasmanis o Acanthite o Arsenopalladinite o Bustamite o Clinohumite o Enstatite o Harmotome o Actinolite o Arsenopyrite o Bytownite o Clinoptilolite o Epidesmine (Stilbite) o Hastingsite o Adularia o Arsenosulvanite (Plagioclase) o Clinozoisite o Epidote o Hausmannite (Orthoclase) o Arsenpolybasite o Cairngorm (Quartz) o Cobaltite o Epistilbite o Hedenbergite o Aegirine o Astrophyllite o Calamine o Cochromite o Epsomite o Hedleyite o Aenigmatite o Atacamite (Hemimorphite) o Coffinite o Erionite o Hematite o Aeschynite o Atokite o Calaverite o Columbite o Erythrite o Hemimorphite o Agardite-Y o Augite o Calciohilairite (Ferrocolumbite) o Euchroite o Hercynite o Agate (Quartz) o Aurostibite o Calcite, see also o Conichalcite o Euxenite o Hessite o Aguilarite o Austinite Manganocalcite o Connellite o Euxenite-Y o Heulandite o Aktashite o Onyx o Copiapite o o Autunite o Fairchildite Hexahydrite o Alabandite o Caledonite o Copper o o Awaruite o Famatinite Hibschite o Albite o Cancrinite o Copper-zinc o o Axinite group o Fayalite Hillebrandite o Algodonite o Carnelian (Quartz) o Coquandite o o Azurite o Feldspar group Hisingerite o Allanite o Cassiterite o Cordierite o o Barite o Ferberite Hongshiite o Allanite-Ce o Catapleiite o Corrensite o o Bastnäsite
    [Show full text]
  • Zirconolite, Chevkinite and Other Rare Earth Minerals from Nepheline Syenites and Peralkaline Granites and Syenites of the Chilwa Alkaline Province, Malawi
    Zirconolite, chevkinite and other rare earth minerals from nepheline syenites and peralkaline granites and syenites of the Chilwa Alkaline Province, Malawi R. G. PLATT Dept. of Geology, Lakehead University, Thunder Bay, Ontario, Canada F. WALL, C. T. WILLIAMS AND A. R. WOOLLEY Dept. of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD, U.K. Abstract Five rare earth-bearing minerals found in rocks of the Chilwa Alkaline Province, Malawi, are described. Zirconolite, occurring in nepheline syenite, is unusual in being optically zoned, and microprobe analyses indicate a correlation of this zoning with variations in Si, Ca, Sr, Th, U, Fe, Nb and probably water; it is argued that this zoning is a hydration effect. A second compositional zoning pattern, neither detectable optically nor affected by the hydration, is indicated by variations in Th, Ce and Y such that, although total REE abundances are similar throughout, there appears to have been REE fractionation during zirconolite growth from relatively heavy-REE and Th-enrichment in crystal cores to light-REE enrichment in crystal rims. Chevkinite is an abundant mineral in the large granite quartz syenite complexes of Zomba and Mulanje, and analyses are given of chevkinites from these localities. There is little variation in composition within each complex, and only slight differences between them; they are all typically light-REE-enriched. The Mulanje material was shown by X-ray diffraction to be chevkinite and not the dimorph perrierite, but chemical arguments are used in considering the Zomba material to be the same species. Other rare earth minerals identified are monazite, fluocerite and bastn/isite.
    [Show full text]
  • Moon Minerals a Visual Guide
    Moon Minerals a visual guide A.G. Tindle and M. Anand Preliminaries Section 1 Preface Virtual microscope work at the Open University began in 1993 meteorites, Martian meteorites and most recently over 500 virtual and has culminated in the on-line collection of over 1000 microscopes of Apollo samples. samples available via the virtual microscope website (here). Early days were spent using LEGO robots to automate a rotating microscope stage thanks to the efforts of our colleague Peter Whalley (now deceased). This automation speeded up image capture and allowed us to take the thousands of photographs needed to make sizeable (Earth-based) virtual microscope collections. Virtual microscope methods are ideal for bringing rare and often unique samples to a wide audience so we were not surprised when 10 years ago we were approached by the UK Science and Technology Facilities Council who asked us to prepare a virtual collection of the 12 Moon rocks they loaned out to schools and universities. This would turn out to be one of many collections built using extra-terrestrial material. The major part of our extra-terrestrial work is web-based and we The authors - Mahesh Anand (left) and Andy Tindle (middle) with colleague have build collections of Europlanet meteorites, UK and Irish Peter Whalley (right). Thank you Peter for your pioneering contribution to the Virtual Microscope project. We could not have produced this book without your earlier efforts. 2 Moon Minerals is our latest output. We see it as a companion volume to Moon Rocks. Members of staff
    [Show full text]
  • Electrical Properties of Cati03
    The University of New South Wales Faculty of Science and Technology School of Materials Science and Engineering Electrical Properties of CaTi03 A Thesis in Ceramic Engineering by Mei-Fang Zhou Submitted in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy March 2004 U N b W 2 7 JAN 2005 LIBRARY CERTIFICATE OF ORIGINALITY I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, nor material which to a substantial extent has been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project’s design and conception or in style, presentation and linguistic expression is acknowledged. (Signed) ACKNOWLEDGMENTS The author would like to express her thanks to the following people for their contributions to the completion of this work: Prof. J. Nowotny, my supervisor, for sparking my interest in this thesis project and for providing valuable advice on various aspects of the project. I am grateful for his constant encouragement and great assistance with the research plan, thesis corrections and valuable discussion. In particular, he contributed exceptional expertise in the defect chemistry of amphoteric semiconducting oxides.
    [Show full text]
  • Petyayan-Vara Rare-Earth Carbonatites (Vuoriyarvi Massif, Russia)
    geosciences Article Ti-Nb Mineralization of Late Carbonatites and Role of Fluids in Its Formation: Petyayan-Vara Rare-Earth Carbonatites (Vuoriyarvi Massif, Russia) Evgeniy Kozlov 1,* ID , Ekaterina Fomina 1, Mikhail Sidorov 1 and Vladimir Shilovskikh 2 ID 1 Geological Institute, Kola Science Centre, Russian Academy of Sciences, 14, Fersmana Street, 184209 Apatity, Russia; [email protected] (E.F.); [email protected] (M.S.) 2 Resource center for Geo-Environmental Research and Modeling (GEOMODEL), St. Petersburg State University, 1, Ulyanovskaya Street, 198504 Saint Petersburg, Russia; [email protected] * Correspondence: [email protected]; Tel.: +7-953-758-7632 Received: 6 July 2018; Accepted: 25 July 2018; Published: 28 July 2018 Abstract: This article is devoted to the geology of titanium-rich varieties of the Petyayan-Vara rare-earth dolomitic carbonatites in Vuoriyarvi, Northwest Russia. Analogues of these varieties are present in many carbonatite complexes. The aim of this study was to investigate the behavior of high field strength elements during the late stages of carbonatite formation. We conducted a multilateral study of titanium- and niobium-bearing minerals, including a petrographic study, Raman spectroscopy, microprobe determination of chemical composition, and electron backscatter diffraction. Three TiO2-polymorphs (anatase, brookite and rutile) and three pyrochlore group members (hydroxycalcio-, fluorcalcio-, and kenoplumbopyrochlore) were found to coexist in the studied rocks. The formation of these minerals occurred in several stages. First, Nb-poor Ti-oxides were formed in the fluid-permeable zones. The overprinting of this assemblage by residual fluids led to the generation of Nb-rich brookite (the main niobium concentrator in the Petyayan-Vara) and minerals of the pyrochlore group.
    [Show full text]
  • Carbonatites of the World, Explored Deposits of Nb and REE—Database and Grade and Tonnage Models
    Carbonatites of the World, Explored Deposits of Nb and REE—Database and Grade and Tonnage Models By Vladimir I. Berger, Donald A. Singer, and Greta J. Orris Open-File Report 2009-1139 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Suzette M. Kimball, Acting Director U.S. Geological Survey, Reston, Virginia: 2009 For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod/ Telephone: 1-888-ASK-USGS For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov/ Telephone: 1-888-ASK-USGS Suggested citation: Berger, V.I., Singer, D.A., and Orris, G.J., 2009, Carbonatites of the world, explored deposits of Nb and REE— database and grade and tonnage models: U.S. Geological Survey Open-File Report 2009-1139, 17 p. and database [http://pubs.usgs.gov/of/2009/1139/]. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. ii Contents Introduction 1 Rules Used 2 Data Fields 2 Preliminary analysis: —Grade and Tonnage Models 13 Acknowledgments 16 References 16 Figures Figure 1. Location of explored Nb– and REE–carbonatite deposits included in the database and grade and tonnage models 4 Figure 2. Cumulative frequency of ore tonnages of Nb– and REE–carbonatite deposits 14 Figure 3 Cumulative frequency of Nb2O5 grades of Nb– and REE–carbonatite deposits 15 Figure 4 Cumulative frequency of RE2O3 grades of Nb– and REE–carbonatite deposits 15 Figure 4 Cumulative frequency of P2O5 grades of Nb– and REE–carbonatite deposits 16 Tables Table 1.
    [Show full text]
  • Features of Crystalline and Electronic Structures of Sm2mtao7 (M=Y, In, Fe) and Their Hydrogen Production Via Photocatalysis
    Ceramics International 43 (2017) 3981–3992 Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint Features of crystalline and electronic structures of Sm2MTaO7 (M=Y, In, Fe) MARK and their hydrogen production via photocatalysis ⁎ Leticia M. Torres-Martíneza, , M.A. Ruíz-Gómezb, E. Moctezumac a Departamento de Ecomateriales y Energía, Facultad de Ingeniería Civil, Universidad Autónoma de Nuevo León UANL, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 64455, México b Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Unidad Mérida, Antigua carretera a Progreso, km 6, Cordemex, Mérida, Yucatán C.P. 97310, México c Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av. Manuel Nava #6, San Luis Potosí, S.L.P. C.P. 78290, México ARTICLE INFO ABSTRACT Keywords: This paper reports on the crystal structure determination of a new phase of Sm2YTaO7 synthesized by a solid- Pyrochlore state reaction. Rietveld refinement using X-ray powder diffraction (XRD) data and electron diffraction using Rietveld analysis transmission electron microscopy (TEM) revealed that Sm2YTaO7 crystallized into an orthorhombic system Crystal structure with space group C2221, and according to the crystalline arrangement, it can be considered as a weberite-type Photocatalysis phase. A detailed analysis of the crystal chemistry of the family with formula Sm MTaO (M=Y, In, Fe, Ga) was Hydrogen production 2 7 performed, which indicated that all of these complex oxides are composed of corner-sharing octahedral layers of TaO6 units within a three-, two- or one-dimensional array. In addition, for comparison, the crystal structure, 3+ 3+ 5+ space group and lattice parameters of approximately 100 previously synthesized oxides in the A2 B B O7 family were collected and analyzed, and a structural map based on the radius ratio rA/rB is reported.
    [Show full text]
  • The Fourteenth International Meeting on Ferroelectricity
    The Fourteenth International Meeting on Ferroelectricity BOOK OF ABSTRACTS San Antonio, Texas, USA September 4th – 8th, 2017 2 SPONSORSHIP 2 3 PREFACE The Fourteenth International Meeting on Ferroelectricity is held on September 4th to 8th, 2017 in San Antonio, Texas, USA. Over the past half century, since this series started (in 1965, at Prague, Czechoslovakia) the meeting is held every four years in different locations around the world, IMF has provided the platform to bring together researchers from academia, industry and government laboratories to share their knowledge in the field and to present the development of novel applications of ferroelectricity in various interdisciplinary and cross-coupled research areas. As a result, the IMF series has nurtured several special Symposia and Conferences in related fields and accelerated the rapid growth and extended interests in the field of ferroelectrics around the globe. The major themes and drives of these premier meetings have been to present the recent developments in the new understandings of fundamentals, advances in the field and bringing out the novel emerging cross-coupled effects among various characteristics of materials such as semiconductors, biosystems, and so on. Over the decades the conference has provided extensive and cumulative understanding of a large family of novel ferroic materials. The previous thirteen IMFs spread over the last fifty years have successfully established the field by serving its goals to the targeted research community. The Fourteenth International Meeting on Ferroelectricity (IMF-2017) Organization committee is pleased to welcome you and thanks for your participation and support to continue this important tradition of the Ferroelectrics Community.
    [Show full text]
  • Baddeleyite Zro2 C 2001-2005 Mineral Data Publishing, Version 1 Crystal Data: Monoclinic
    Baddeleyite ZrO2 c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Monoclinic. Point Group: 2/m. Crystals commonly tabular on {100} and somewhat elongated on [010], or short to long prismatic along [001], to 6 cm; rarely equant; prism faces striated k [001]; radially fibrous with concentric banding in botryoidal masses. Twinning: Ubiquitous; on {100} and {110}, both may be polysynthetic; rare on {201}. Physical Properties: Cleavage: {001} nearly perfect, {010} and {110} less perfect. Fracture: Subconchoidal to uneven. Tenacity: Brittle. Hardness = 6.5 D(meas.) = 5.40–6.02 D(calc.) = [5.83] Blue-green cathodoluminescence. Optical Properties: Transparent; in dark-colored specimens, only in thin fragments. Color: Colorless to yellow, green, greenish or reddish brown, brown, iron-black; colorless to brown in transmitted light. Streak: White to brownish white. Luster: Greasy to vitreous; nearly submetallic in black crystals. Optical Class: Biaxial (–). Pleochroism: X = yellow, reddish brown, oil-green; Y = oil-green, reddish brown; Z = brown, light brown. Orientation: X ∧ c =13◦; Y = b. Dispersion: r> v, rather strong. Absorption: X > Y > Z. α = 2.13(1) β = 2.19(1) γ = 2.20(1) 2V(meas.) = 30(1)◦ 2V(calc.) = 28◦ Cell Data: Space Group: P 21/c (synthetic). a = 5.1505(1) b = 5.2116(1) c = 5.3173(1) β =99.230(1)◦ Z=4 X-ray Powder Pattern: Phalaborwa, South Africa. 3.15 (10), 2.835 (9), 2.62 (5), 1.817 (5), 3.66 (4), 3.51 (4), 1.847 (4) Chemistry: (1) (2) (1) (2) (1) (2) SiO2 0.19 0.08 HfO2 0.93 CaO 0.06 TiO2 0.56 Fe2O3 0.82 LOI 0.28 ZrO2 98.90 97.8 FeO 1.3 Total 100.25 100.67 (1) Balangoda, Sri Lanka.
    [Show full text]
  • Fivefold-Coordinated Ti4+In Metamict Zirconolite and Titanite: a New Occurrence Shown by Ti K-Edge XANES Spectroscopy
    American Mineralogist, Volume 82, pages 44-50, 1997 Fivefold-coordinated Ti4+in metamict zirconolite and titanite: A new occurrence shown by Ti K-edge XANES spectroscopy FRANC;OIS F ARGES Laboratoire de physique et mecanique des geomateriaux, Universite de Marne-la-vallee, URA CNRS 734 and LURE (and Stanford University), 2 rue de la butte verte, 93166 Noisy Ie Grand cedex, France ABSTRACT The coordination environments of Ti in two fully metamict zirconolite samples and two partially metamict titanite samples were determined using high-resolution, X-ray absorp- tion near-edge structure (XANES) spectroscopy at the Ti K edge. Fivefold-coordinated Ti is the dominant Ti species in the zirconolite samples (~80 :!::10% of the total Ti atoms). This unusual Ti coordination is also possible in the titanite samples. No significant evidence for 141Tiwas found in any of the samples studied. Comparison with other amorphous materials, such as other metamict minerals (aes- chynite and pyrochlore) and titanosilicate glasses and melts, suggests that fivefold coor- dination is rather common for Ti4+ in aperiodic structures. However, the metamict state is characterized by the presence of unusual trigonal bipyramids around 15ITi4+. INTRODUCTION terpretation for the coordination of Ti in these metamict Titanite and zirconolite (ideally CaTiSiOs and Ca- phases is proposed, which suggests, for the first time, the ZrTi207, respectively) are important phases in various presence of major amounts of ISJTiin the radiation-dam- crystalline titanate-phase assemblages proposed as nucle- aged portions of zirconolite (and possibly of titanite) and ar waste forms (see Lutze and Ewing 1988; Ringwood et in several other complex metamict oxide minerals, such as al.
    [Show full text]
  • A Glossary of Uranium- and Thorium-Bearing Minerals
    GEOLOGICAL SURVEY CIRCULAR 74 April 1950 A GLOSSARY OF URANIUM­ AND THORIUM-BEARING MINERALS By Judith Weiss Frondel and Michael F1eischer UNITED STATES DEPARTMENT OF THE INTERIOR Oscar L. Chapman, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director WASHINGTON. D. C. Free on application to the Director, Geological Survey, Washington 25, D. C. A GLOSSAR-Y OF URANIUM- AND THORIUM-BEARING MINERALS By Judith Weiss Fronde! and Michael Fleischer CONTENTS Introduction ••oooooooooo••••••oo•-•oo•••oo••••••••••oooo•oo••oooooo••oo•oo•oo•oooo••oooooooo•oo• 1 .A. Uranium and thorium minerals oooo oo oo ......................... oo .... oo oo oo oo oo oooooo oo 2 B. Minerals with minor amounts of uranium and thorium 000000000000000000000000.... 10 C. Minerals that should be tested for uranium and thorium ...... 00 .. 00000000000000 14 D. Minerals that are non-uranium- or non-thorium­ bearing, but that have been reported to contain impurities or intergrowths of uranium, thorium, or rare-earth minerals oooooo•oo ............ oo ... oo .. oooooo'""""oo" .. 0000 16 Index oo ...... oooooo•oo••••oo•oooo•oo•oooo•·~· .. •oooo•oooooooooooo•oooooo•oooooo•oooo••oo•••oooo••• 18 INTRODUCTION The U. S. ·Geological Survey has for some time been making a systematic survey of da~ pertaining to uranium and thorium minerals and to those minerals that contain trace1 or more of uranium and thorium. This survey consists of collecting authoritative chemical, optical, and X-ray diffraction data from the literature and of adding to these data, where inadequate, by work in the laboratory. The results will he reported from time to time, and the authors welcome in- formation on additional data and names.
    [Show full text]