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- Title
New Data on the Isomorphism in Eudialyte-Group Minerals. VII: Crystal Structure of the Eudialyte–Sergevanite Series Mineral from the Lovozero Alkaline Massif.
- Authors
Rastsvetaeva, R. K.; Chukanov, N. V.; Van, K. V.
- Abstract
An intermediate member of the eudialyte–sergevanite solid-solution series has been investigated by X-ray diffraction analysis, electron probe microanalysis, and IR spectroscopy. The trigonal unit-cell parameters of the mineral are found to be a = 14.1944(4) Å, c = 30.294(1) Å, and V = 5286.0(3) Å3; sp. gr. R3. The crystal structure is refined to the final reliability factor R = 4.48% in the anisotropic approximation of atomic displacements, using 2420 reflections with F > 3σ(F). The idealized formula of the mineral (Z = 3) is Na14Sr(Ca3Mn3)(Na2Fe)Zr3Si26O72(OH)3Cl · H2O. An increase in the Ca and Fe contents in comparison with the holotype sergevanite does not increase symmetry. The problems of genesis of calcium-poor minerals with eudialyte-type structure are discussed.
- Subjects
CRYSTAL structure; ELECTRON probe microanalysis; ATOMIC displacements; MINERALS; X-ray diffraction
- Publication
Crystallography Reports, 2020, Vol 65, Issue 4, p554
- ISSN
1063-7745
- Publication type
Article
- DOI
10.1134/S1063774520040173