Optical Spectra and Color Nature of Lithium Amphiboles
Optical absorption spectra of two lithium amphiboles of the pedrisite group from rare-metal peg-matites of the Sangilen rare-metal province in the southeastern part of Tyva have been studied. One of them – a limit magnesian fluoro-sodium pedrisite of yellow-green color – was taken from the rocks hos...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Kazan Federal University
2016-03-01
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| Series: | Учёные записки Казанского университета: Серия Естественные науки |
| Subjects: | |
| Online Access: | http://kpfu.ru/portal/docs/F_1533347785/158_1_est_7.pdf |
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| Summary: | Optical absorption spectra of two lithium amphiboles of the pedrisite group from rare-metal peg-matites of the Sangilen rare-metal province in the southeastern part of Tyva have been studied. One of them – a limit magnesian fluoro-sodium pedrisite of yellow-green color – was taken from the rocks hosting pegmatites, and another one – fluoro-sodium ferro-pedrisite of violet-blue color – was taken from pegmatites as such. It has been demonstrated that the color of the yellow-green mineral is associated with absorption bands of Cr3+ ions in the octahedral coordination. Absorption bands of Cr3+ ions in the spectrum of fluoro-sodium pedrisite are formed by a transmission window in the yellow-green region of the spectrum. Therefore, the color of this sample is yellow-green. The color of violet-blue pedrisite is de-fined by intensive absorption bands of charge transfer Fe2+ → Fe3+ 550, 680 nm. Very strong absorption bands of 550 and 680 nm are formed by a transmission window in the violet-blue region of the spectrum. Thus, the color of ferro-pedrisite is violet-blue. |
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| ISSN: | 1815-6169 2500-218X |