Studying the features of complex beryllium-containing silicate phases co-crystallization in zonal samples using the x-ray electron probe microanalysis method
https://doi.org/10.24930/1681-9004-2024-24-2-416-423
Abstract
Research subject. Silicate ingots containing four species-forming components Be, Mg, Al, and Si and belonging to the crystallization region of beryllium indialite (with the formula of Mg2BeAl2Si6O18 and a beryl-type structure). Aim. To investigate the fundamental problem of identifying the patterns of matter differentiation and the stable and metastable phase formation in silicate matrices. Methods. The evolution of the phase composition of silicate melts was registered using a temperature gradient method. Results. New data on the features of phase transformations in silicate melts belonging to the region of beryllium indialite were obtained by electron probe microanalysis (EPMA). Co-existing metastable and stable mineral phases were identified, and the similarity of their compositions with different structures was shown. The nature of impurity phases at each stage of crystallization was established. Conclusions. The evolutionary sequence of phase associations ensuring the crystallization of beryllium indialite and metastable phases of a similar composition, the nature of which is determined by the initial ratio of components, was experimentally recorded. The range of possible phase associations that co-crystallize or replace a stable phase with a beryl structure in melts from the region of existence of beryllium indialite in the BeO–MgO–Al2O3–SiO2 system was extended. The selectivity of the coloring element chromium entry into various phases of the studied system is shown depending on the capabilities of their structure. The addition of a chromophore is a reliable criterion for visualizing successive layers, zones, and areas of changing phase associations in the final ingot.
Keywords
crystal-forming medium,
metastable phases,
evolutionary mineral genesis,
species-forming elements redistribution,
beryllian indialite,
mixed Be–Mg–Al silicate
Supporting agencies: The study was carried out within the governmental assignment of Project 0284–2021–0005. The author highly appreciates the contribution by Dr. M.A. Mikhailov (IGC, SB RAS), the founder and leader of beryllian indialite research.
About the Authors
S. G. Mamontova
A.P. Vinogradov Institute of Geochemistry, SB RAS
Russian Federation
Russian Federation
Svetlana G. Mamontova
1A Favorsky st., Irkutsk 664033
O. Yu. Belozerova
A.P. Vinogradov Institute of Geochemistry, SB RAS
Russian Federation
Russian Federation
Olga Yu. Belozerova
1A Favorsky st., Irkutsk 664033
References
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For citations:
Mamontova S.G., Belozerova O.Yu. Studying the features of complex beryllium-containing silicate phases co-crystallization in zonal samples using the x-ray electron probe microanalysis method. LITHOSPHERE (Russia). 2024;24(2):416-423. (In Russ.) https://doi.org/10.24930/1681-9004-2024-24-2-416-423
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