Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat ArticlesThe ElementsThe Rock H. Currier Digital LibraryGeologic Time
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsUsersMineral MuseumsClubs & OrganizationsMineral Shows & EventsThe Mindat DirectoryDevice SettingsThe Mineral Quiz
Photo SearchPhoto GalleriesSearch by ColorNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day GalleryPhotography
╳Discussions
💬 Home🔎 Search📅 LatestGroups
EducationOpen discussion area.Fakes & FraudsOpen discussion area.Field CollectingOpen discussion area.FossilsOpen discussion area.Gems and GemologyOpen discussion area.GeneralOpen discussion area.How to ContributeOpen discussion area.Identity HelpOpen discussion area.Improving Mindat.orgOpen discussion area.LocalitiesOpen discussion area.Lost and Stolen SpecimensOpen discussion area.MarketplaceOpen discussion area.MeteoritesOpen discussion area.Mindat ProductsOpen discussion area.Mineral ExchangesOpen discussion area.Mineral PhotographyOpen discussion area.Mineral ShowsOpen discussion area.Mineralogical ClassificationOpen discussion area.Mineralogy CourseOpen discussion area.MineralsOpen discussion area.Minerals and MuseumsOpen discussion area.PhotosOpen discussion area.Techniques for CollectorsOpen discussion area.The Rock H. Currier Digital LibraryOpen discussion area.UV MineralsOpen discussion area.Recent Images in Discussions
Mineralogical ClassificationMeta-autunite: monovalent cations in structures (Can.Min.)
1st Oct 2004 19:04 UTCMarco E. Ciriotti
Compounds of the meta-autunite group containing monovalent cations (Li, Na, K, Rb, Cs, Ag, Tl) have been synthesized by diffusion in gels or by hydrothermal methods, and their crystal structures determined. Single-crystal X-ray-diffraction intensity data were collected at room temperature using MoKα radiation and a CCD-based area detector. These compounds contain the autunite-type sheet with composition <(UO2)(XO4)>–, X = P or As, which involves the sharing of equatorial vertices of uranyl square bipyramids with tetrahedra. The interlayer region contains cations and H2O groups, and the sheets are linked by hydrogen bonding and through bonds from the interlayer cations to oxygen atoms of the sheets. The structural roles of the interlayer cations in determining the symmetries and hydration states observed are discussed. The smallest monovalent cation, Li, occurs in tetrahedral coordination between fourfold squares of hydrogen-bonded H2O groups. Despite a wide range in ionic radius, Na, K, Rb, Ag and Tl randomly substitute for H2O groups in the interlayer, in the same fashion as their ammonium and oxonium analogues. The large Cs cation adopts independent crystallographic sites in the interlayer. The size difference between Cs and the other monovalent cations probably prevents their direct substitution, and may limit the extent of solid solution. With the exception of the Rb and Cs compounds, chemically corresponding uranyl phosphates and uranyl arsenates are isostructural. The structural similarity of Rb<(UO2)(AsO4)>(H2O)3 with metazeunerite, Cu<(UO2)(AsO4)>2(H2O)8, may indicate a mechanism of solid solution for monovalent and divalent interlayer cations in the meta-autunite group. Crystallographic data: Li<(UO2)(PO4)>(H2O)4: tetragonal, P4/n, a 6.9555(2), c 9.1389(3) Å, R1 = 1.2%; Na<(UO2)(PO4)>(H2O)3: tetragonal, P4/ncc, a 6.9616(2), c 17.2677(9) Å, R1 = 2.3%; Na<(UO2)(AsO4)>(H2O)3: tetragonal, P4/ncc, a 7.1504(3), c 17.325(1) Å, R1 = 1.7%; K<(UO2)(AsO4)>(H2O)3: tetragonal, P4/ncc, a 7.1669(17), c 17.867(6) Å, R1 = 3.4%; Rb<(UO2)(PO4)>(H2O)3: tetragonal, P4/ncc, a 7.0106(2), c 17.9772(8) Å, R1 = 2.6%; Rb<(UO2 )(AsO4)>(H2O)3: tetragonal, P4/n, a 7.1904(3), c 17.643(1) Å, R1 = 1.9%; Ag<(UO2)(PO4)>(H2O)3: tetragonal, P4/ncc, a 6.9332(1), c 16.9313(6) Å, R1 = 1.6%; Ag<(UO2)(AsO4)>(H2O)3: tetragonal, P4/ncc, a 7.0901(2), c 17.0453 (8) Å, R1 = 2.1%; Tl<(UO2)(PO4)>(H2O)3: tetragonal, P4/ncc, a 7.019(3), c 17.98(1) Å, R1 = 3.2%; Tl<(UO2)(AsO4)>(H2O)3: tetragonal, P4/ncc, a 7.1905(8), c 17.970(3) Å, R1 = 3.4%; Cs2<(UO2)(PO4)>2(H2O)5: monoclinic, P21/n, a 9.8716(7), b 9.9550(7), c 17.6465(13) Å, β = 90.402(2)°, R1 = 2.8%; Cs(H3O)<(UO2)(AsO4)>2(H2O)5: monoclinic, P21/n, a 14.2614(17), b 7.1428(9), c 17.221(2) Å, β 91.110(3)°, R1 = 4.6%.
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 25, 2024 02:25:23
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 25, 2024 02:25:23