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dc.contributor.authorSokolova, E.
dc.contributor.authorGenovese, Alessandro
dc.contributor.authorFalqui, Andrea
dc.contributor.authorHawthorne, F. C.
dc.contributor.authorCámara, F.
dc.date.accessioned2017-04-30T10:17:01Z
dc.date.available2017-04-30T10:17:01Z
dc.date.issued2018-01-26
dc.identifier.citationSokolova E, Genovese A, Falqui A, Hawthorne FC, Cámara F (2017) PREPUBLICATION: From structure topology to chemical composition. XXIII. Revision of the crystal structure and chemical formula of zvyaginite, a seidozerite-supergroup mineral from the Lovozero alkaline massif, Kola peninsula, Russia. Mineralogical Magazine. Available: http://dx.doi.org/10.1180/minmag.2017.081.015.
dc.identifier.issn0026-461X
dc.identifier.doi10.1180/minmag.2017.081.015
dc.identifier.urihttp://hdl.handle.net/10754/623295
dc.description.abstractThe crystal structure and chemical formula of zvyaginite, ideally Na2ZnTiNb2(Si2O7)2O2(OH)2 (H2O)4, a lamprophyllite-group mineral of the seidozerite supergroup from the type locality, Mt. Malyi Punkaruaiv, Lovozero alkaline massif, Kola Peninsula, Russia have been revised. The crystal structure was refined with a new origin in space group C⎯1, a = 10.769(2), b = 14.276(3), c = 12.101(2) Å, α = 105.45(3), β = 95.17(3), γ = 90.04(3)°, V = 1785.3(3.2) Å3, R1 = 9.23%. The electron-microprobe analysis gave the following empirical formula [calculated on 22 (O + F)]:(Na0.75Ca0.09K0.04��1.12)Σ2 (Na1.12Zn0.88Mn0.17Fe2+0.04��0.79)Σ3(Nb1.68Ti1.25Al0.07)Σ3 (Si4.03O14)O2 [(OH)1.11F0.89]Σ2(H2O)4, Z = 4. Electron-diffraction patterns have prominent streaking along c* and HRTEM images show an intergrowth of crystalline zvyaginite with two distinct phases, both of which are partially amorphous. The crystal structure of zvyaginite is an array of TS (Titanium Silicate) blocks connected via hydrogen bonds between H2O groups. The TS block consists of HOH sheets (H = heteropolyhedral, O = octahedral) parallel to (001). In the O sheet, the [6]MO(1,4,5) sites are occupied mainly by Ti, Zn and Na and the [6]MO(2,3) sites are occupied by Na at less than 50%. In the H sheet, the [6]MH(1,2) sites are occupied mainly by Nb and the [8]AP(1) and [8]AP(2) sites are occupied mainly by Na and ��. The MH and AP polyhedra and Si2O7 groups constitute the H sheet. The ideal structural formula is Na��Nb2NaZn��Ti(Si2O7)2O2(OH)2(H2O)4. Zvyaginite is a Zn-bearing and Na-poor analogue of epistolite, ideally (Na��)Nb2Na3Ti(Si2O7)2O2(OH)2(H2O)4. Epistolite and zvyaginite are related by the following substitution in the O sheet of the TS-block: (Na+2)epi ↔ Zn2+ zvy + ��zvy. The doubling of the t1 and t2 translations of zvyaginite relative to those of epistolite is due to the order of Zn and Na along a (t1) and b (t2) in the O sheet of zvyaginite.
dc.description.sponsorshipWe are grateful to an anonymous reviewer and Associate Editor Peter Leverett for useful comments. We thank Mark A. Cooper for collection of single-crystal X-ray data for three zvyaginite crystals. ES acknowledges financial support by a Canada Research Chair in Crystallography and Mineralogy to FCH. FCH acknowledges support by a Canada Research Chair in Crystallography and Mineralogy and by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada, and by Innovation Grants from the Canada Foundation for Innovation.
dc.publisherMineralogical Society
dc.relation.urlhttp://www.ingentaconnect.com/content/minsoc/mag/pre-prints/content-mm-1410
dc.rightsArchived with thanks to Mineralogical Magazine
dc.subjectChemical formula
dc.subjectCrystal-structure refinement
dc.subjectEMP analysis
dc.subjectElectron diffraction
dc.subjectEpistolite
dc.subjectHRTEM
dc.subjectLamprophyllite group
dc.subjectSeidozerite supergroup
dc.subjectTS-block minerals
dc.subjectZvyaginite
dc.titlePREPUBLICATION: From structure topology to chemical composition. XXIII. Revision of the crystal structure and chemical formula of zvyaginite, a seidozerite-supergroup mineral from the Lovozero alkaline massif, Kola peninsula, Russia
dc.typeArticle
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Division
dc.contributor.departmentBioscience Program
dc.contributor.departmentElectron Microscopy
dc.identifier.journalMineralogical Magazine
dc.eprint.versionPublisher's Version/PDF
dc.contributor.institutionDepartment of Geological Sciences, University of Manitoba, 125 Dysart Road, Winnipeg, MB, R3T 2N2 Canada
dc.contributor.institutionDipartimento di Scienze della Terra “Ardito Desio”, Università degli Studi di Milano, Via Mangiagalli 34, 20133, Milano, Italy
kaust.personGenovese, Alessandro
kaust.personFalqui, Andrea
refterms.dateFOA2018-04-01T00:00:00Z
dc.date.published-online2018-01-26
dc.date.published-print2017-12


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