Micro-Raman spectroscopy of gem-quality chrysoprase from the Biga-çanakkale region of Turkey
The commercial quantities of gem-quality dark green chrysoprase are found as the fracture fillings covered with a weathering crust in the silicified serpentinites throughout the border of a metamorphic zone in the Biga-çanakkale region of Turkey. However, the green-stained opaque quartz materials ar...
| Published in: | Journal of African Earth Sciences |
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| Main Authors: | , , |
| Other Authors: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
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2011
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| Subjects: | |
| Online Access: | https://hdl.handle.net/20.500.12438/5328 https://doi.org/10.1016/j.jafrearsci.2011.08.002 |
| Summary: | The commercial quantities of gem-quality dark green chrysoprase are found as the fracture fillings covered with a weathering crust in the silicified serpentinites throughout the border of a metamorphic zone in the Biga-çanakkale region of Turkey. However, the green-stained opaque quartz materials are also present in the same deposit, but these materials are common and in low-demand according to chrysoprase in terms of gemmological importance. Thus, it is necessary to distinguish these two similar materials from each other non-destructively. In addition, all chrysoprase roughs in this deposit also have alpha-quartz and moganite inclusions. Accordingly, dispersive (visible) confocal micro-Raman spectroscopy (DCµRS) allows us to distinguish clearly the chalcedonic-quartz silica phase (fibrous quartz (chalcedony)) from the crystalline-quartz silica phase (fine-grained alpha-quartz) in the case of both quartz inclusions in the chrysoprase material and itself of the green-stained quartz material in the same deposit.This study characterizes the Biga chrysoprase (Turkey) in terms of silica building phases, chemical content, and individual Raman bands, using several destructive and non-destructive analytical techniques.The Raman spectra show that the most characteristic intensive and the widest Raman bands peaked at about 498 and 460cm-1 can be inferred to ?2 doubly symmetric bending mode of [SiO4/M] centers. The " M" includes the some cationic substitutions of Si by Fe, Cr, Mn, As, Ni, Pb, Sb, and Zn, and K and Na as well. The second characteristic Raman band peaked at about 206cm-1 can be inferred to single translational libration mode. The last readable Raman bands peaked at about 139 and 126cm-1 can be inferred to doubly translational libration modes as well. In addition, the weaker Raman bands peaked at about 1577, 1430, 1303, 1160, 1082, 549, 394, 352, and 259cm-1 are also present.As a result, the dispersive confocal micro-Raman spectrum of chrysoprase is directly related to its silica building phases and trace element implications. © 2011 Elsevier Ltd. British Association for Psychopharmacology This study is a part of the thesis prepared for the B.Sc., by the second author. The confocal micro-Raman spectrometer used in this study was purchased with the grant of the BAP Project, No. BAP-2009.KB.FEN.051, of Dokuz Eylül University. Accordingly, the authors wish to give great thanks to Prof. Dr. R. Sami AKSOY, Prof. Dr. İ. Hakkı BAHAR, Cengiz HEPİYİLER, and Prof. Dr. Necdet TÜRK for their help and support during the purchasing procedure of the spectrometer, and also to Instructor Helen Margaret MORAN-ÇAĞLAR from Dokuz Eylül University, School of Foreign Languages, for proof-reading the manuscript, and ultimately to referees’ for constructive review, recommendations, and patience. |
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