Crystal structure and indicatopy significance of odikhinchaite from the Khibiny alkaline complex

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Marco E. Ciriotti
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Crystal structure and indicatopy significance of odikhinchaite from the Khibiny alkaline complex

Messaggio da Marco E. Ciriotti » gio 03 giu, 2021 13:24

Referenza:
▪ Rastsvetaeva, R.K., Chukanov, N.V., Lisitsin, D.V., Voronin, M., Varlamov, D.A. (2021): Crystal structure and indicatopy significance of odikhinchaite from the Khibiny alkaline complex. Vestnik of the Institute of Geology of the Komi Science Center of the Ural Branch of the Russian Academy of Sciences, 316(2), 3-9.

Abstract:
Odikhinchaite, a Sr-Mn-Nb-CO3-dominant eudialyte-group mineral from the Khibiny alkaline complex has been investigated using the methods of electron probe microanalysis, X-ray diffraction, infrared and Mössbauer spectroscopy. The crystal structure was refined to R = 3.4 % in the anisotropic approximation of atomic displacements using 3815 independent reflections with F > 3 (F). The unit-cell parameters are: a = 14.2709(1), c = 30.023(1) Å, V = 5295.33(7) Å3; the space group is R3m. The simplified formula of the mineral is (Z = 3): Na11Sr3(Mn2+,Fe2+,Fe3+)Ca6Zr3Nb[Si25O72(OH)](CO3)Cl(OH,O)4. The studied sample is the second find of this rare mineral worldwide, represented by a variety with high Fe content in the M2 micro-region, belonging to the taseqite — odikhinchaite solid-solution series. The significance of odikhinchaite as an indicator of a stage corresponding to maximum Sr activity in specific ultraagpaitic pegmatites is discussed.
Marco E. Ciriotti

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