Blue dravite (“indicolite”) from the Elahera gem field, Sri Lanka
- Author(s)
- L. Nasdala, M. Wildner, G. Giester, C. Chanmuang N., M. R. Scicchitano, C. Hauzenberger
- Abstract
A strongly dichroic (vivid blue to near-colourless) tourmaline specimen from the Elahera gem field, central Sri Lanka, was identified as dravite. The sample shows strong Fe2+-related optical absorption (E perpendicular to c) in the red range and comparably weak red emission due to Cr3+. The discovery of virtually Cu-free blue dravite (with a Li content of only about 3 ppm) shows that blue colour in gem tourmaline is not restricted to Cu- and/or Fe-bearing elbaite and other lithium tourmalines. Also, this study reconfirms the usefulness of Raman spectroscopy for non-destructive mineral identification. The sensitivity of Raman shifts of O-H stretching bands to their nearest-neighbour cations allowed us to exclude the presence of significant amounts of Li ions, even before obtaining results of light-element analysis. (C) 2021 Gem-A (The Gemmological Association of Great Britain)
- Organisation(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum, Karl-Franzens-Universität Graz
- Journal
- The Journal of Gemmology
- Volume
- 37
- Pages
- 618-630
- No. of pages
- 13
- ISSN
- 1355-4565
- DOI
- https://doi.org/10.15506/JoG.2021.37.6.618
- Publication date
- 06-2021
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 104026 Spectroscopy, 105116 Mineralogy, 105113 Crystallography
- Keywords
- ASJC Scopus subject areas
- Geochemistry and Petrology
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/c9a0a693-8b9b-48eb-817e-077a22437d82