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Crystal Chemistry, Isomorphism, and Thermal Conversions of Extra-Framework Components in Sodalite-Group Minerals.
- Source :
- Minerals (2075-163X); Jul2022, Vol. 12 Issue 7, pN.PAG-N.PAG, 31p
- Publication Year :
- 2022
-
Abstract
- Isomorphic substitutions of extra-framework components in sodalite-group aluminosilicate minerals and their thermal conversions have been investigated using infrared, Raman, electron spin resonance (ESR), as well as ultraviolet, visible and near infrared (UV–Vis–near IR) absorption spectroscopy methods and involving chemical and X-ray diffraction data. Sodalite-related minerals from gem lazurite deposits (haüyne, lazurite, and slyudyankaite) are characterized by wide variations in S-bearing extra-framework components including SO<subscript>4</subscript><superscript>2−</superscript> and various polysulfide groups (S<subscript>2</subscript><superscript>●−</superscript>, S<subscript>3</subscript><superscript>●−</superscript>, S<subscript>4</subscript><superscript>●−</superscript> radical anions, and S<subscript>4</subscript> and S<subscript>6</subscript> neutral molecules) as well as the presence of CO<subscript>2</subscript> molecules. Heating at 700 °C under reducing conditions results in the transformation of initial S-bearing groups SO<subscript>4</subscript><superscript>2−</superscript> and S<subscript>3</subscript><superscript>●−</superscript> to a mixture of S<superscript>2−</superscript>, HS<superscript>−</superscript>, S<subscript>2</subscript><superscript>●−</superscript>, and S<subscript>4</subscript><superscript>●−</superscript> and transformation of CO<subscript>2</subscript> to a mixture of CO<subscript>3</subscript><superscript>2−</superscript> and C<subscript>2</subscript>O<subscript>4</subscript><superscript>2−</superscript> or HC<subscript>2</subscript>O<subscript>4</subscript><superscript>−</superscript> anionic groups. Further heating at 800 °C in air results in the decomposition of carbonate and oxalate groups, restoration of the SO<subscript>4</subscript><superscript>2−</superscript> and S<subscript>3</subscript><superscript>●−</superscript> groups, and a sharp transformation of the framework. The HS<superscript>−</superscript> anion is stable only under reducing conditions, whereas the S<subscript>3</subscript><superscript>●−</superscript> radical anion is the most stable polysulfide group. The HS<superscript>−</superscript>-dominant sodalite-group mineral sapozhnikovite forms a wide solid-solution series with sodalite. The conditions required for the formation of HS<superscript>−</superscript>- and CO<subscript>2</subscript><superscript>0</superscript>-bearing sodalite-group minerals are discussed. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 2075163X
- Volume :
- 12
- Issue :
- 7
- Database :
- Complementary Index
- Journal :
- Minerals (2075-163X)
- Publication Type :
- Academic Journal
- Accession number :
- 158299346
- Full Text :
- https://doi.org/10.3390/min12070887