Crystal Structure of Cl-Deficient Analogue of Taseqite from Odikhincha Massif
- Authors: Rastsvetaeva R.K.1, Chukanov N.V.2, Zaitsev V.A.3, Aksenov S.M.1,3, Viktorova K.A.1
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Affiliations:
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,”
- Institute of Problems of Chemical Physics
- Vernadsky Institute of Geochemistry and Analytical Chemistry
- Issue: Vol 63, No 3 (2018)
- Pages: 349-357
- Section: Structure of Inorganic Compounds
- URL: https://journals.rcsi.science/1063-7745/article/view/192434
- DOI: https://doi.org/10.1134/S1063774518030240
- ID: 192434
Cite item
Abstract
An eudialyte group mineral, found in pegmatites of the Odikhincha massif (the northern part of the Siberian platform), has been investigated using X-ray diffraction, IR spectroscopy, and Raman spectroscopy. The mineral is characterized by a high strontium content and a low chlorine content. It has a trigonal unit cell with the following parameters: a = 14.2700(6) Å and c = 30.057(1) Å; V = 5300.6(1) Å3; sp. gr. R3m. The structure has been refined to R = 0.047 in the anisotropic approximation of atomic displacements using 1697F > 4σ(F). The idealized formula (Z = 3) was found to be Na12Sr2Ca6Fe32+ Zr3NbSi25O72(OH,O)4Cl(Н2О)0.2. The chemical composition and structure of this mineral are close to those of taseqite; however, it differs from the holotype sample by a low chlorine content and peculiarities of cation distribution over basic structure sites. A comparative analysis of strontium-rich eudialytes has revealed their important crystallochemical feature: selective concentration of strontium in the N4 site. Thus, taseqite, along with heterophyllosilicates, may play a role of strontium concentrator in agpaitic pegmatites.
About the authors
R. K. Rastsvetaeva
Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,”
Author for correspondence.
Email: rast@crys.ras.ru
Russian Federation, Moscow, 119333
N. V. Chukanov
Institute of Problems of Chemical Physics
Email: rast@crys.ras.ru
Russian Federation, Chernogolovka, Moscow Region, 142432
V. A. Zaitsev
Vernadsky Institute of Geochemistry and Analytical Chemistry
Email: rast@crys.ras.ru
Russian Federation, Moscow, 119334
S. M. Aksenov
Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,”; Vernadsky Institute of Geochemistry and Analytical Chemistry
Email: rast@crys.ras.ru
Russian Federation, Moscow, 119333; Moscow, 119334
K. A. Viktorova
Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,”
Email: rast@crys.ras.ru
Russian Federation, Moscow, 119333