WANG Hui1, LIANG Rong2*, LAN Yan1,2, PAN Hai-hua3, AI Xia1, LIN Hui-feng4
(1. National Gemstone Testing Center Shenzhen Lab, Shenzhen 518026, China;
2. NGTC Gems & Jewelry Institute of Shenzhen , Shenzhen 518026, China;
3. National Gems& Artworks Appraisal Company Limited of Shenzhen, Shenzhen 518026, China;
4. Shenzhen Rose Blue Jewelry Co., Ltd. , Shenzhen 518026, China)
Abstract: The spectral characteristics, chemical composition, and coloration mechanism of emeralds from the Menzies area in Western Australian have been studied in this paper by using Infrared absorption spectroscopy, Raman spectroscopy, UV-Vis-NIR absorption spectroscopy, Laser induced breakdown spectroscopy (LIBS), and Electron probe microanalysis (EPMA). Infrared absorption spectra showed that the Menzies emerald has vibration characteristics of [Si6O18] group, with relatively high absorption intensity of the II type water comparing to that of the I type water in its structural channels. The characteristic Raman spectral peaks of the Menzies emerald are mainly located at 323 cm-1, 397 cm-1, 685 cm-1, and 1067 cm-1, with some detected weak scattering peaks at 142 cm-1and 190 cm-1. The UV-Vis-NIR absorption spectra were mainly the Cr3+, V3+, Fe2+and Fe3+ absorption bands in which the peaks at 424 nm and 611 nm are caused by joint action of Cr3+ and V3+, and the peaks at 644 nm, 661 nm and 682 nm are caused by Cr3+. EPMA data of the Menzies emerald show that its Cr2O3 content is significantly higher than its V2O3 content. The results of UV-Vis-NIR absorption spectra and EPMA show that the color of Menzies emerald was mainly produced by Cr3+. At the same time, the comparative analysis of the spectra and chemical compositions between the Menzies emerald and Yunnan emerald has been carried out in order to provide the reference for the gemological identification and quality evaluation of the Menzies emerald.
Keywords: Menzies emerald; spectroscopic characteristics; chemical composition; coloration mechanism
ACTA MINERALOGICA SINICA Vol. 39, No. 6, 2019, page 657-663
