FLUORINE-RICH HIBSCHITE FROM SILICOCARBONATITE, AFRIKANDA COMPLEX, RUSSIA: CRYSTAL CHEMISTRY AND CONDITIONS OF CRYSTALLIZATION (Articolo in rivista)

Type
Label
  • FLUORINE-RICH HIBSCHITE FROM SILICOCARBONATITE, AFRIKANDA COMPLEX, RUSSIA: CRYSTAL CHEMISTRY AND CONDITIONS OF CRYSTALLIZATION (Articolo in rivista) (literal)
Anno
  • 2008-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.3749/canmin.46.4.1033 (literal)
Alternative label
  • Chakhmouradian AR; Cooper MA; Medici L; Hawthorne FC; Adar F (2008)
    FLUORINE-RICH HIBSCHITE FROM SILICOCARBONATITE, AFRIKANDA COMPLEX, RUSSIA: CRYSTAL CHEMISTRY AND CONDITIONS OF CRYSTALLIZATION
    in Canadian mineralogist
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Chakhmouradian AR; Cooper MA; Medici L; Hawthorne FC; Adar F (literal)
Pagina inizio
  • 1033 (literal)
Pagina fine
  • 1042 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 46 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali
  • 10 (literal)
Note
  • Scopu (literal)
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • (1) Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada (2) Istituto di Metodologie per l'Analisi Ambientale, Tito Scalo, I-85050 Potenza, Italy (3) Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada (4) Molecular and Microanalysis Division, Horiba Jobin Yvon, Edison, New Jersey 08820, U.S.A. (literal)
Titolo
  • FLUORINE-RICH HIBSCHITE FROM SILICOCARBONATITE, AFRIKANDA COMPLEX, RUSSIA: CRYSTAL CHEMISTRY AND CONDITIONS OF CRYSTALLIZATION (literal)
Abstract
  • Calcite - amphibole - diopside silicocarbonatite from the Afrikanda complex, in the Kola Peninsula, northwestern Russia, contains abundant crystals of F-rich hibschite associated with titanite, chlorite, calciocatapleiite and calcite. The crystals range from 10 to 50 mm across and consist of an oscillatory-zoned core and a uniform rim arising from variations in Al and Fe contents across the crystal. The hibschite contains from 4.2 to 6.0 wt.% F, which is unparalleled by any F-bearing silicate garnet described to date. The compositional variation of the Afrikanda hibschite can be described by the formula Grs(57-63)Kt(21-27)Fgr(8-11)Adr(0-13), where Grs, Kt and Adr stand for the grossular, katoite and andradite, respectively, and Fgr denotes the hypothetical end-member Ca3Al2F12. The average Fgr content is 10 mol.%. The crystal structure of F-rich hibschite was refined in space group Ia (3) over bard to R-1 = 2.8%. In agreement with the chemical data, the refinement shows that about one-third of the tetrahedrally coordinated positions (Z) are vacant. These vacancies are coordinated by (OH)(-) and F- anions, which results in expansion of the unit cell [a = 12.037(3)angstrom] relative to that of grossular. The size of the Z-centered tetrahedron is sensitive to the substitution of (OH)(-) by F-, as indicated by the smaller center-to-corner and corner-to-corner distances measured for the Afrikanda hibschite relative to garnets with a similar Si content along the grossular - katoite join. The F- rich hibschite crystallized in the final stages of silicocarbonatite evolution from a low-temperature (200-250 degrees C) deuteric fluid with log a(H+)(aq) approximate to log a(F-)(aq) approximate to -5. (literal)
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