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 ClassificationRevision of formula and structure of schüllerite
13th Feb 2014 09:11 UTCMarco E. Ciriotti Manager
▪ Sokolova, E., Hawthorne, F.C., Abdu, Y.A. (2013): From structure topology to chemical composition. XV. Titanium silicates: Revision of the crystal structure and chemical formula of schüllerite, Na2Ba2Mg2Ti2(Si2O7)2O2F2, from the Eifel Volcanic Region, Germany. Canadian Mineralogist, 51, 715-725.
Abstract:
The crystal structure of schüllerite, ideally Na2Ba2Mg2Ti2(Si2O7)2O2F2, a 5.396(1), b 7.071(1), c 10.226(2) Å, α 99.73(3), β 99.55(3), γ 90.09(3)°, V 379.1(2) Å3, Z = 1, from the Eifel volcanic region, Germany, has been refined in the space group P-1 to R = 1.33% using 2247 observed (Fo > 4σF) reflections collected with a single-crystal Bruker D8 three-circle diffractometer equipped with a rotating-anode generator (MoKα radiation), multilayer optics and an APEX-II detector. The empirical formula for schüllerite was calculated on the basis of 18 (O + F) anions: (Na1.10Ca0.43Mn0.30Fe2+0.17)∑2(Ba1.57Sr0.14K0.14□0.15)∑2 (Mg0.79Fe2+0.71Na0.33Fe3+0.17)∑2 (Ti1.67Fe3+0.21Nb0.09Zr0.02Al0.01)∑2Si3.95O15.93F2.07, Dcalc.= 3.879 g/cm3, Z = 1, with Fe3+/(Fe2++Fe3+) ratio determined by Mössbauer spectroscopy. Schüllerite is a Group-IV TS-block mineral: Ti + Mg = 4 apfu. The crystal structure of schüllerite is an alternation of TS (Titanium Silicate) and I (intermediate) blocks of the ideal composition 4− and 4+, respectively. The TS block is composed of the central O (octahedral) sheet and two adjacent H (heteropolyhedral) sheets. In the O sheet, there are two brookite-like chains of MO octahedra of the following ideal compositions: 12− and 14− ; the ideal composition of the O sheet is 0. The H sheet is composed of the <5>-coordinated Ti-dominant MH polyhedra and Si2O7 groups; the composition of the two H sheets is 4−. In schüllerite, the TS block has a topology characteristic of Group IV of TS-block minerals: two H sheets connect to the O sheet such that two Si2O7 groups link to the Mg-dominant octahedra of the O sheet adjacent along t1. In the O sheet, occurrence of divalent cations at the MO(1) site results in the presence of monovalent anions, F−, at the XOA site. The AP site of the H sheet is occupied mainly by Ba; the AP site is shifted from the plane of the H sheet, and Ba atoms constitute the I block of the composition 4+. Schüllerite is the only mineral of Group IV that has (1) a brookite-like 12− chain of octahedra in the O sheet; (2) <5>-coordinated Ti in the H sheet; (3) Ba atoms in the I block. The ideal structural formula of schüllerite is of the form AP2MH2MO4(Si2O7)2(XOM)2(XOA)2 : Ba2Ti2Na2Mg2Ti2(Si2O7)2O2F2, Z = 1.
16th Feb 2014 11:11 UTCGuenter Blass
I need the full article!
Do you have of them a PDF file?
nice Sunday
Günter
17th Feb 2014 12:05 UTCMarco E. Ciriotti Manager
Ciao.
17th Feb 2014 16:51 UTCGuenter Blass
many thanks,
Günter
18th Feb 2014 15:20 UTCUwe Kolitsch Manager
(The originally described structure, determined on a different crystal, was modelled in P1).
18th Feb 2014 15:23 UTCUwe Kolitsch Manager
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 18, 2024 01:28:16
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 18, 2024 01:28:16