CATION DISTRIBUTION IN AMPHIBOLES SYNTHESIZED ALONG THE GA ANALOGUE OF THE TREMOLITE-ALUMINOTSCHERMAKITE JOIN
- DSpace Home
- →
- Геология России
- →
- ELibrary
- →
- View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.
dc.contributor.author | Jenkins D.M. | |
dc.contributor.author | Ishida K. | |
dc.contributor.author | Liogys V. | |
dc.contributor.author | Ghosh D. | |
dc.date.accessioned | 2021-04-16T05:17:19Z | |
dc.date.available | 2021-04-16T05:17:19Z | |
dc.date.issued | 2002 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=960409 | |
dc.identifier.citation | Physics and Chemistry of Minerals, 2002, 29, 2, 87-97 | |
dc.identifier.issn | 0342-1791 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/27914 | |
dc.description.abstract | Amphiboles were synthesized from bulk compositions prepared along the join Ca1.8Mg5.2Si8O22(OH)2-Ca1.8Mg3Ga4Si6O22(OH)2 hydrothermally at 750-850 °C and 1.0-1.8 GPa, and along the join Ca2Mg5Si8O22F2-Ca2Mg3Ga4Si6O22F2, anhydrously at 1000 °C and 0.7 GPa to document how closely the tschermak-type substitution is obeyed in these analogues of aluminous amphiboles. Electron-microprobe analyses and Rietveld X-ray diffraction structure refinements were performed to determine cation site occupancies. The extent of Ga substitution was found to be limited in both joins, but with the fluorine series having about twice the Ga content (0.6 atoms per formula unit, apfu) of the hydroxyl-series amphiboles (0.3 apfu). The tschermak-type substitution was followed very closely in the hydroxyl series with essentially equal partitioning of Ga between tetrahedral and octahedral sites. The fluorine-series amphiboles deviated significantly from the tschermak-type substitution and, instead, appeared to follow a substitution that is close to a Ca-pargasite substitution of the type: [6]Ga3++2[4]Ga3++1/2[A] Ca2+ = [6]Mg2++2[4]Si4++1/2[A]□. Infrared spectroscopy revealed an inverse correlation between the intensity of the OH-stretching bands and the Ga content for the hydroxyl- and fluorine-series amphiboles. The direct correlation between the Ga and F content and inverse relationship between the Ga and OH content may be a general phenomenon present in other minerals and suggests, for example, that high F contents in titanite are controlled by the Al content of the host rock and that there may be similar direct Al-F correlations in tschermakitic amphiboles. Evidence for the possibility that Al (Ga) might substitute onto only a subset of the tetrahedral sites in tschermakitic amphiboles was sought but not observed in this study. | |
dc.subject | AMPHIBOLE | |
dc.subject | TSCHERMAK | |
dc.subject | TREMOLITE | |
dc.subject | FLUORINE | |
dc.subject | GALLIUM | |
dc.title | CATION DISTRIBUTION IN AMPHIBOLES SYNTHESIZED ALONG THE GA ANALOGUE OF THE TREMOLITE-ALUMINOTSCHERMAKITE JOIN | |
dc.type | Статья |
Files in this item
This item appears in the following Collection(s)
-
ELibrary
Метаданные публикаций с сайта https://www.elibrary.ru