Sulfur-bearing sodalite – hackmanite in alkaline pegmatites of the Inagli massif (Aldan shield): crystal and chemical features, photochromism and luminescence

Radomskaya T. A., Kaneva E. V., Shendrik R. Yu., Suvorova L. F., Vladykin N. V.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2020. V. 149. N 2. P. 42-54

https://doi.org/10.31857/S0869605520020069

Language: Russian

Abstract

The sulfur-containing sodalite – hackmanite has been found for the first time in alkaline pegmatites of the alkaline-ultrabasic Inagli massif (South Yakutia, Russia). Pegmatites with hackmanite have an amphibole-orthoclase (± diopside) and microcline-albite-amphibole (± aegirine) composition. Chemical composition of hackmanite (EPMA, wt %) is Na₂O 25.6, Al₂O₃ 31.56, SiO₂ 37.20, Cl 7.32, S 0.57, K₂O 0.09, CaO 0.03, FeO 0.04. The empirical formula, calculated on 12 cations (Si, Al) is Na_0.87K_0.02Fe²⁺_0.01(Al_5.96Si_6.04)_Σ=12O_24.09(Cl_1.65S_0.17)_Σ=1.82 . The spectra of optical absorption, luminescence and excitation of the mineral revealed the presence of molecular centers O^-₂ and S^-₂. The EPR spectrum is indicative of the absence of a vacancy charge compensation mechanism in the studied sample of hackmanite. Thus, additional anions in the hackmanite of the Inagli massif are also represented by and with an S–S bond length of 2.06 Å. Structural data are indicative of the absence of anions S^2-, S^2-₂ and (SO₄)^2-.

Keywords: hackmanite, sodalite, Inagli alkaline-ultrabasic massif, Aldan shield, electron probe microanalysis, X-ray diffraction analysis, infrared spectroscopy, electron paramagnetic resonance.