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Title: Crystal structure of modular sodium-rich and low-iron eudialyte from Lovozero alkaline massif

Abstract

The structure of the sodium-rich representative of the eudialyte group found by A.P. Khomyakov at the Lovozero massif (Kola Peninsula) is studied by X-ray diffraction. The trigonal cell parameters are: a = 14.2032(1) and c = 60.612(1) Å, V = 10589.13 Å3, space group R3m. The structure is refined to the final R = 5.0% in the anisotropic approximation of atomic displacement parameters using 3742|F| > 3σ(F). The idealized formula (Z = 3) is Na{sub 37}Ca{sub 10}Mn{sub 2}FeZr{sub 6}Si{sub 50}(Ti, Nb){sub 2}O{sub 144}(OH){sub 5}Cl{sub 3} · H{sub 2}O. Like other 24-layer minerals of the eudialyte group, this mineral has a modular structure. Its structure contains two modules, namely, “alluaivite” (with an admixture of “eudialyte”) and “kentbrooksite,” called according to the main structural fragments of alluaivite, eudialyte, and kentbrooksite. The mineral found at the Lovozero alkaline massif shows some chemical and symmetry-structural distinctions from the close-in-composition labyrinthite modular mineral from the Khibiny massif. The difference between the minerals stems from different geochemical conditions of mineral formation in the two regions.

Authors:
; ;  [1]
  1. Federal Scientific Research Center “Crystallography and Photonics”, Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)
Publication Date:
OSTI Identifier:
22645397
Resource Type:
Journal Article
Resource Relation:
Journal Name: Crystallography Reports; Journal Volume: 61; Journal Issue: 5; Other Information: Copyright (c) 2016 Pleiades Publishing, Inc.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; ATOMIC DISPLACEMENTS; GEOCHEMISTRY; MODULAR STRUCTURES; SILICATE MINERALS; SODIUM; SPACE GROUPS; TRIGONAL LATTICES; X-RAY DIFFRACTION

Citation Formats

Rozenberg, K. A., Rastsvetaeva, R. K., E-mail: rast@ns.crys.ras.ru, and Aksenov, S. M. Crystal structure of modular sodium-rich and low-iron eudialyte from Lovozero alkaline massif. United States: N. p., 2016. Web. doi:10.1134/S1063774516050187.
Rozenberg, K. A., Rastsvetaeva, R. K., E-mail: rast@ns.crys.ras.ru, & Aksenov, S. M. Crystal structure of modular sodium-rich and low-iron eudialyte from Lovozero alkaline massif. United States. doi:10.1134/S1063774516050187.
Rozenberg, K. A., Rastsvetaeva, R. K., E-mail: rast@ns.crys.ras.ru, and Aksenov, S. M. 2016. "Crystal structure of modular sodium-rich and low-iron eudialyte from Lovozero alkaline massif". United States. doi:10.1134/S1063774516050187.
@article{osti_22645397,
title = {Crystal structure of modular sodium-rich and low-iron eudialyte from Lovozero alkaline massif},
author = {Rozenberg, K. A. and Rastsvetaeva, R. K., E-mail: rast@ns.crys.ras.ru and Aksenov, S. M.},
abstractNote = {The structure of the sodium-rich representative of the eudialyte group found by A.P. Khomyakov at the Lovozero massif (Kola Peninsula) is studied by X-ray diffraction. The trigonal cell parameters are: a = 14.2032(1) and c = 60.612(1) Å, V = 10589.13 Å3, space group R3m. The structure is refined to the final R = 5.0% in the anisotropic approximation of atomic displacement parameters using 3742|F| > 3σ(F). The idealized formula (Z = 3) is Na{sub 37}Ca{sub 10}Mn{sub 2}FeZr{sub 6}Si{sub 50}(Ti, Nb){sub 2}O{sub 144}(OH){sub 5}Cl{sub 3} · H{sub 2}O. Like other 24-layer minerals of the eudialyte group, this mineral has a modular structure. Its structure contains two modules, namely, “alluaivite” (with an admixture of “eudialyte”) and “kentbrooksite,” called according to the main structural fragments of alluaivite, eudialyte, and kentbrooksite. The mineral found at the Lovozero alkaline massif shows some chemical and symmetry-structural distinctions from the close-in-composition labyrinthite modular mineral from the Khibiny massif. The difference between the minerals stems from different geochemical conditions of mineral formation in the two regions.},
doi = {10.1134/S1063774516050187},
journal = {Crystallography Reports},
number = 5,
volume = 61,
place = {United States},
year = 2016,
month = 9
}
  • Hydrogen-bearing vuonnemite from the Shkatulka hyperagpaitic pegmatite (the Lovozero alkaline massif, Kola Peninsula) was studied by single-crystal X-ray diffraction. The triclinic unit-cell parameters are as follows: a = 5.4712(1) Angstrom-Sign , b = 7.1626(1) Angstrom-Sign , c = 14.3702(3) Angstrom-Sign , {alpha} = 92.623(2) Degree-Sign , {beta} = 95.135(1) Degree-Sign , {gamma} = 90.440(1) Degree-Sign , sp. gr. P1, R = 3.4%. The Na{sup +} cations and H{sub 2}O molecules are ordered in sites between the packets. The water molecules are hydrogen bonded to the PO{sub 4} tetrahedra.
  • The structure of a new representative of the eudialyte group with the formula (Na,Sr,K){sub 18}Ca{sub 6}Zr{sub 3}Fe[Si{sub 25}O{sub 72}](OH){sub 2}Cl . H{sub 2}O from the Lovozero massif (Kola Peninsula) was studied by X-ray diffraction. The trigonal unit-cell parameters are a = 14.226 A, c = 30.339 A, sp. gr. R3-barm; the R factor is 0.045 based on 990 reflections. This sample is of interest as a sodium-rich and iron-poor mineral having a rare centrosymmetric structure, in which the M(2) site is occupied predominantly by sodium atoms. The dependence of the formation of centrosymmetric and non-centrosymmetric structures on the composition ofmore » eudialyte-group minerals was analyzed.« less
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