Identification of Some Gem Quality Blue to Green Li-Tourmalines
Due to their appealing colors, gem quality tourmalines, particularly the blue to green Cu- and Mn-bearing Li-tourmalines known as the Paraíba type, have been of significant interest since their discovery at the end of 1980s. At the same time, the demand of other similar colored tourmalines increased...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-12-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/14/1/44 |
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| author | Lorenzo Pasetti Laura Borromeo Danilo Bersani Sergio Andò Jurgen Schnellrath Ugo Hennebois Stefanos Karampelas |
| author_facet | Lorenzo Pasetti Laura Borromeo Danilo Bersani Sergio Andò Jurgen Schnellrath Ugo Hennebois Stefanos Karampelas |
| author_sort | Lorenzo Pasetti |
| collection | DOAJ |
| description | Due to their appealing colors, gem quality tourmalines, particularly the blue to green Cu- and Mn-bearing Li-tourmalines known as the Paraíba type, have been of significant interest since their discovery at the end of 1980s. At the same time, the demand of other similar colored tourmalines increased. Most Paraíba-type tourmalines belong to the elbaite species; however, liddicoatite gems can also be found. Recognizing and classifying various tourmaline species, especially these valued Paraíba-type tourmalines, are important for geologists, mineralogists, mineral collectors, and gemologists. This study explores the application of Raman spectroscopy in random crystal orientations to distinguish between the elbaite and liddicoatite tourmaline species. Raman spectra were collected from faceted blue to green Li-tourmalines alongside chemical analysis using EDXRF (Energy Dispersive X-ray Fluorescence), UV-Vis-NIR (Ultraviolet-Visible-Near InfraRed Spectroscopy), and PL (Photoluminescence spectroscopy) to provide comprehensive characterization. The results show that Raman spectroscopy, particularly in the OH stretching region, is a useful tool for differentiating elbaite from liddicoatite, and this identification remains consistent regardless of crystal orientation. The fingerprint region in the Raman spectra, on the other hand, is orientation-dependent and can only differentiate the two species when detected in specific orientations. Furthermore, Paraíba-type tourmalines can be identified by visible-near infrared (Vis-NIR) spectroscopy, although not by Raman spectroscopy. |
| first_indexed | 2024-03-08T10:39:10Z |
| format | Article |
| id | doaj.art-390fa93f751a4574891c9fae012d6d26 |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-08T10:39:10Z |
| publishDate | 2023-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-390fa93f751a4574891c9fae012d6d262024-01-26T17:52:19ZengMDPI AGMinerals2075-163X2023-12-011414410.3390/min14010044Identification of Some Gem Quality Blue to Green Li-TourmalinesLorenzo Pasetti0Laura Borromeo1Danilo Bersani2Sergio Andò3Jurgen Schnellrath4Ugo Hennebois5Stefanos Karampelas6Department of Mathematical, Physical and Computer Sciences, University of Parma, 43124 Parma, ItalyLaboratory for Provenance Studies, Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20126 Milan, ItalyDepartment of Mathematical, Physical and Computer Sciences, University of Parma, 43124 Parma, ItalyLaboratory for Provenance Studies, Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20126 Milan, ItalyCentro de Tecnologia Mineral—Centre for Mineral Technology, Rio de Janeiro 21941-908, BrazilLaboratoire Français de Gemmologie (LFG), 75009 Paris, FranceLaboratoire Français de Gemmologie (LFG), 75009 Paris, FranceDue to their appealing colors, gem quality tourmalines, particularly the blue to green Cu- and Mn-bearing Li-tourmalines known as the Paraíba type, have been of significant interest since their discovery at the end of 1980s. At the same time, the demand of other similar colored tourmalines increased. Most Paraíba-type tourmalines belong to the elbaite species; however, liddicoatite gems can also be found. Recognizing and classifying various tourmaline species, especially these valued Paraíba-type tourmalines, are important for geologists, mineralogists, mineral collectors, and gemologists. This study explores the application of Raman spectroscopy in random crystal orientations to distinguish between the elbaite and liddicoatite tourmaline species. Raman spectra were collected from faceted blue to green Li-tourmalines alongside chemical analysis using EDXRF (Energy Dispersive X-ray Fluorescence), UV-Vis-NIR (Ultraviolet-Visible-Near InfraRed Spectroscopy), and PL (Photoluminescence spectroscopy) to provide comprehensive characterization. The results show that Raman spectroscopy, particularly in the OH stretching region, is a useful tool for differentiating elbaite from liddicoatite, and this identification remains consistent regardless of crystal orientation. The fingerprint region in the Raman spectra, on the other hand, is orientation-dependent and can only differentiate the two species when detected in specific orientations. Furthermore, Paraíba-type tourmalines can be identified by visible-near infrared (Vis-NIR) spectroscopy, although not by Raman spectroscopy.https://www.mdpi.com/2075-163X/14/1/44tourmalineParaíba-typeelbaiteliddicoatiteRaman spectroscopy |
| spellingShingle | Lorenzo Pasetti Laura Borromeo Danilo Bersani Sergio Andò Jurgen Schnellrath Ugo Hennebois Stefanos Karampelas Identification of Some Gem Quality Blue to Green Li-Tourmalines Minerals tourmaline Paraíba-type elbaite liddicoatite Raman spectroscopy |
| title | Identification of Some Gem Quality Blue to Green Li-Tourmalines |
| title_full | Identification of Some Gem Quality Blue to Green Li-Tourmalines |
| title_fullStr | Identification of Some Gem Quality Blue to Green Li-Tourmalines |
| title_full_unstemmed | Identification of Some Gem Quality Blue to Green Li-Tourmalines |
| title_short | Identification of Some Gem Quality Blue to Green Li-Tourmalines |
| title_sort | identification of some gem quality blue to green li tourmalines |
| topic | tourmaline Paraíba-type elbaite liddicoatite Raman spectroscopy |
| url | https://www.mdpi.com/2075-163X/14/1/44 |
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