Study on Mineral Composition and Spectral Characteristics of “Middle East Turquoise”
XU Ya-fen1, LIU Xian-yu1*, CHEN Quan-li2, XU Chang3
1. School of Jewelry, Shanghai Jian Qiao University, Shanghai 201306, China
2. Gemmological Institute, China University of Geosciences (Wuhan), Wuhan 430074, China
3. School of Earth Sciences, China University of Geosciences (Wuhan), Wuhan 430074, China
Abstract:Recently, A kind of jade has appeared in gem wholessale markets, which is similar to veins turquoise, called “Middle East turquoise” and brings trouble to the normal order of the jewelry market. This paper analysed Microlithography, X-ray powder crystal diffraction, infrared spectroscopy, Raman spectroscopy, micro-UV visible spectroscopy and trace elements to determine its mineralogy and spectral characteristics. The results showed that “Middle East turquoise” is a kind of quartzite jade, mainly composed of transparent-microtransparent blue and white spherical minerals, with opaque lignite minerals, glass luster, the refractive index of 1.53~1.54, the relative density of about 2.48~2.60. Under short and long wave ultraviolet light, the blue part is blue and white fluorescence. Micrographic analysis shows that the blue and white annules are mostly crystalline radioactive pulp, part of the iron oxide brown; the center of the annule is 0.05~0.3 mm granular single crystal quartz. X-ray powder crystal diffraction analysis found that “Middle East turquoise” also contains low crystallization. FTIR spectroscopy shows that the characteristic absorption peak of “Middle East turquoise” coincides with quartz jade and 1 179, 1 104, 798, 781, 690, 540, 488 cm-1, resulting from Si—O asymmetric extension vibration, Si—O—Si symmetric extension vibration and Si—O bending vibration. Raman spectroscopy shows that the Raman shift with quartz 466 and 210 cm-1 in the blue annual and central part of the sample, and the brown-red part of the sample has not only quartz Raman shift but also the Raman shift 302 and 551 cm-1. Micro-UV visible spectrum and trace element analysis show that the blue of “Middle East turquoise” positively correlates with Cu element content, showing a 600~700 nm absorption band. While the appearance of “Middle East turquoise” is similar to wire turquoise, its mineral composition is not turquoise but a collection of crystalline quartz and chalcedony, containing a small amount of needle ore, so it should not be confused with turquoise. It can be named “quartzite jade”.
Key words:“Middle East turquoise”; Mineral composition; X-ray powder diffraction; Quartzite jade; Color origin
徐娅芬,刘衔宇,陈全莉,徐 畅. “中东绿松石”的矿物成分和谱学特征研究[J]. 光谱学与光谱分析, 2023, 43(09): 2862-2867.
XU Ya-fen, LIU Xian-yu, CHEN Quan-li, XU Chang. Study on Mineral Composition and Spectral Characteristics of “Middle East Turquoise”. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(09): 2862-2867.
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