title: Кристаллохимия нептунита Хан-Богдинского щелочного массива (Монголия)
metadata.name: dc.date.accessioned
metadata.value: 2020-09-09T07:31:13Z
metadata.lang: -
metadata.name: dc.date.available
metadata.value: 2020-09-09T07:31:13Z
metadata.lang: -
metadata.name: dc.date.issued
metadata.value: 2016
metadata.lang: -
metadata.name: dc.identifier.uri
metadata.value: http://hdl.handle.net/11701/19307
metadata.lang: -
metadata.name: dc.description.abstract
metadata.value: Crystal chemical characteristics have been studied for neptunite from alkaline granites of the
  Khan Bogdo massif (Southern Mongolia). The mineral occurs to be the practically clear Fe-variety of
  its species. Refinement of its crystal structure was carried out in two space groups: centric C2/c and
  acentric Cc. It is indicated that correct space group is the acentric Cc due to ordering of octahedral cations
  Ti and Fe. The structure was refined to R1 = 0.025 (wR2 = 0.057) for 4889 reflections with
  |Fo|   4sF. Unit cell parameters: a = 16.4542(7), b = 12.5115(4), ñ = 9.9980(4) Å, b = 115.542(5)°,
  V = 1857.10(15) Å3, Z = 4. Ti octahedra show strong distortions: one bond Ti—O 1.75 Å, another
  bond 2.20 Å, and four Ti—O bonds around 2.0 Å. Fe octahedra have a more regular shape with
  an average bond length Fe—O 2.13—2.14 Å. Empirical formula calculated on the basis of chemical
  analysis is (K0.86Cs0.02Zn0.02Ca0.01)S0.91Na1.90Li0.82(Fe1.54Fe Mn Mn
  2
  0.22
  3
  0.16 0.04
  + + )S1.96Ti2.1(Si7.76Al0.25)O24.
  Structural formula is K0.97Na1.90(Li0.94Na0.06)S1.00(Fe1.80Mn0.15Mg0.05)S2.00Ti2Si8O22(O,OH)2. Idealized
  formula is KNa2LiFe2Ti2Si8O24.
  Key words: Fe-dominant neptunite, refined crystal structure, equivalent and anisotropic displacement
  parameters, inter-atomic distances, pyroxene type and octahedral chains, mangan-neptunite.
metadata.lang: en_GB
metadata.name: dc.title
metadata.value: Кристаллохимия нептунита Хан-Богдинского щелочного массива (Монголия)
metadata.lang: en_GB
resources.filename: 5.pdf
resources.url: https://dspace.spbu.ru/bitstream/11701/19307/1/5.pdf
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