... incorporate U 5+ . Richetite is the third mineral containing pentavalent uranium that occurs in nature. Table 1. Summary of data collection conditions and refinement parameters for richetite Structural formula (Fe 0.31 2+ Mg 0.19 )Pb 4.86 [U 5+ (U 6+ O2) 17 O 18 (OH) 14 ](H 2 O) ~19.5...

...Peter C. Burns; Robert J. Finch Abstract Determination of the structure of wyartite provides the first evidence for a pentavalent-U mineral. The structure of wyartite, CaU (super 5+) (UO 2 ) 2 (CO 3 )O 4 (OH)(H 2 O) 7 , Z = 4, orthorhombic, a = 11.2706(8), b = 7.1055(5), c = 20.807(1) Aa, V...

... hexavalent and pentavalent uranium from the Shinkolobwe mine, Democratic Republic of Congo. Crystals of shinkolobweite are dark reddish-brown prisms up to 0.5 mm in length, occurring on a matrix of massive uraninite associated with fourmarierite, rutherfordine, soddyite, and sklodowskite. Crystals...

...) § E-mail address : [email protected] 19 09 2006 06 10 2005 © 2006 Mineralogical Association of Canada 2006 dehydrated wyartite wyartite crystal structure carbonate uranyl pentavalent uranium dehydration spent nuclear fuel wyartite déshydratée...

.... References cited Belai , N. , Frisch , M. , Ilton , E.S. , Ravel , B. , and Cahill , C.L. ( 2008 ) Pentavalent uranium oxide via reduction of [UO 2 ] 2+ under hydrothermal reaction conditions. Inorganic Chemistry , 47 , 10,135 – 10,140 . Blatov , V.A. ( 2004...

...- or tetravalent form (in which state it is highly immobile). The conditions of its oxidation to pentavalent form have been discussed by Garrels (1953; 1955). An analysis of the data in respect of trace element constitution of the rocks and soils shows that despite there being an appreciable quantity of vanadium...

...: crystallographic evidence for the first pentavalent-uranium mineral . Am. Mineral . 84 , 1456 – 1460 . Burns , P.C. & Hanchar , J.M. ( 1999 ): The structure of masuyite, Pb[(UO2)3O3(OH)2](H 2 O)3, and its relationship to protasite . Can. Mineral . 37 , 1483 – 1491 . Burns , P.C...

... unusual conditions during this process. X-ray absorption spectroscopy indicates that Sb in the philipsbornite–segnitite is fully oxidised (0.1–0.4 apfu Sb 5+ , octahedral coordination on the G site). Pentavalent Sb together with the presence of ferric oxides and arsenates and uranyl minerals suggest...

... in the case of Np, although the pentavalent state is the more stable ( Morss et al. 2006 ). In contrast, pentavalent uranium is at most stable in solution over a narrow range of conditions, and far fewer structures are known with pentavalent uranium relative to hexavalent uranium ( Morss et al. 2006...

... . Burns , P.C. & Finch , R.J. ( 1999 ): Wyartite: crystallographic evidence for the first pentavalent-uranium mineral . Am. Mineral . 84 , 1456 – 1460 . Burns , P.C. & Hanchar , J.M. ( 1999 ): The structure of masuyite, Pb[(UO2)3O3(OH)2](H 2 O)3, and its relationship...

...., Uranium: Mineralogy, Geochemistry and The Environment , 38 , 23 – 90 . Reviews in Mineralogy, Mineralogical Society of America , Washington, D.C . Burns , P.C. and Finch , R.J. ( 1999 ) Wyartite: crystallographic evidence for the first pentavalent-uranium mineral . American...

... baddeleyite-melt distribution coefficients of D Pa / D U = 5.8(2) and 4.1(2) are obtained for Vesuvius and Laacher See, respectively. Speciation-dependent (Pa 4+ vs. Pa 5+ ) partitioning coefficients ( D values) from crystal lattice strain models for tetra- and pentavalent proxy ions significantly exceed D Pa...

... of actinide elements into the structures of U 6+ phases formed during the oxidation of spent nuclear fuel . J. Nucl. Mater . 245 , 1 – 9 . Burns , P.C. & Finch , R.J. ( 1999 ): Wyartite: crystallographic evidence for the first pentavalent-uranium mineral . Am. Mineral . 84 , 1456...

... for radionuclide release in a nuclear repository. Journal of Nuclear Materials , 265 , 218 –223. Burns, P.C. and Finch, R.J. ( 1999 ) Wyartite: crystallographic evidence for the first pentavalent-uranium mineral. American Mineralogist , 84 , 1456 –1460. Burns, P.C., Miller, M.L., and Ewing, R.C. ( 1996...

... higher than that of pentavalent As ( Zheng et al. 2005 ; Finkelman et al . 1999 , 2002 ). Additionally, the migration behaviour of As during the transformation process depends on the mode of As occurrence in coal ( Donahue & Hendry 2003 ). Arsenic occurring in sulphate, carbonate, sulphide...

... polymerization . Can. Mineral . 35 , 1551 – 1570 . Burns , P.C. & Finch , R.J. ( 1999 ): Wyartite: crystallographic evidence for the first pentavalent-uranium mineral . Am. Mineral . 84 , 1456 – 1460 . Burns , P.C. , Finch , R.J. , Hawthorne , F.C. , Miller , M.L...

... ): The crystal chemistry of hexavalent uranium: polyhedron geometries, bond-valence parameters, and polymerization of polyhedra . Can. Mineral . 35 , 1551 – 1570 . Burns , P.C. & Finch , R.J. ( 1999 ): Wyartite: crystallographic evidence for the first pentavalent-uranium mineral . Am...

... recently most-read publications, according to GeoScience World, include the following: Shinkolobweite, from the Shinkolobwe Mine, Democratic Republic of Congo: A New Mineral Containing Uranium in the Rare Pentavalent Oxidation State, by Travis Olds, Aaron Lussier, Václav Petek, Jakub Plá il, Anthony Kampf...

... , M.J. , Hynes , A.J. , Charnock , J.M. , Mosselmans , J.F.W. , Hennig , C. , Steele , H. , Collison , D. , Vaughan , D.J. , Pattrick , R.A.D. , Reed , W.A. and Moyes , L.N. ( 2004 ) X-ray absorption spectroscopy studies of reactions of technetium, uranium...