Geology of Ore Deposits

, Volume 49, Issue 8, pp 835–838 | Cite as

Refinement of the mangan-neptunite crystal structure

  • A. A. ZolotarevJr.
  • S. V. Krivovichev
  • V. N. Yakovenchuk
Article

Abstract

The crystal structure of mangan-neptunite, a manganese analogue of neptunite, has been refined in two space groups (Cc and C2/c). The mineral is monoclinic, with the correct space group Cc; the unit-cell dimensions are: a = 16.4821(6), b = 12.5195(4), c = 10.0292(3) Å, β = 115.474(1)°, and V = 1868.31 Å3. The crystal structure has been refined to R1 = 0.0307 (wR2 = 0.0901) on the basis of 4892 observed reflections with |Fhkl| ≥ 4σ|Fhkl|. The most plausible acentric model is caused by the Ti- and (Fe, Mn, Mg)-ordering in the structure. Ti-octahedrons are strongly distorted and consist of short bond Ti-O (1.7 Å), one long bond (2.2 Å), and four equal bonds (2.0 Å). Fe-octahedrons are regularly shaped, with all Fe-O bonds being approximately identical.

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Copyright information

© Pleiades Publishing, Ltd. 2007

Authors and Affiliations

  • A. A. ZolotarevJr.
    • 1
  • S. V. Krivovichev
    • 1
  • V. N. Yakovenchuk
    • 2
  1. 1.Geology FacultySt. Petersburg State UniversitySt. PetersburgRussia
  2. 2.Geological Institute, Kola Scientific CenterRussian Academy of SciencesApatityRussia

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