Iron K-Edge Xanes Study of Heated Green Beryl from Madagascar

Authors

  • Chawalit CHANKHANTHA Gems and Jewelry Industrial Development Section, Department of Industrial Promotion, Ministry of Industry, Bangkok 10110
  • Panjawan THANASUTHIPITAK Gemmology Program, Department of Geological Sciences, Faculty of Science, Chiang Mai University, Chiang Mai 50200
  • Pinit KIDKHUNTHOD Synchrotron Light Research Institute (Public Organization), Nakhon Ratchasima 30000

Keywords:

Beryl, heat treatment, UV-Vis-NIR, FTIR, XANES

Abstract

Rough green beryls from Madagascar were studied for their gemological characteristics after heat treatment. The conversion of the iron oxidation state after heating was studied using the modern technique of X-ray absorption spectroscopy. The X-ray absorption near edge spectroscopy (XANES) results are in conclusively agreement with the traditional Ultraviolet-visible-near infrared (UV-Vis-NIR) technique, where Fe3+ in an octahedral site is changed into Fe2+ after heat treatment. The undesirable yellow tinge in the stone, therefore, is expelled and, thus, an attractive blue color is developed. The green beryls contained moderate amounts of chromophore iron (up to 1.08 wt.% FeO(total)), and relatively low amounts of Cs and Na. Fourier transform infrared (FTIR) spectroscopic features and chemical analyses are consistent with alkali-poor beryl. The gemological characterization of Malagasy green beryl is also presented in detail.

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Published

2016-04-11

How to Cite

CHANKHANTHA, C., THANASUTHIPITAK, P., & KIDKHUNTHOD, P. (2016). Iron K-Edge Xanes Study of Heated Green Beryl from Madagascar. Walailak Journal of Science and Technology (WJST), 13(12), 977–983. Retrieved from https://wjst.wu.ac.th/index.php/wjst/article/view/2380