“加瓷”处理绿松石的成分及谱学特征研究

doi:10.3964/j.issn.1000-0593(2021)07-2245-06

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Abstract In recent years, a kind of turquoise treated with a new type of inorganic binder has appeared on the market. The turquoise treated by this method is very similar to the natural turquoise, which is generally characterized by a fine structure, glassy luster or greasy luster. It is called “porcelain-added” turquoise in markets. Conventional gemological testing instruments, infrared absorption spectrometers, UV-Vis spectrometers and energy dispersive X-ray fluorescence spectrometers were used to systematically study and analyze the gemological properties, vibration spectrum characteristics and chemical composition characteristics of “porcelain-added” turquoise. The results show that the density of turquoise samples treated with “porcelain” is mostly less than 2.2 g·cm^-3, and its density is related to the density of turquoise before treatment. The samples treated with “porcelain” are mainly turquoise with a lower density. The turquoise treated by “porcelain” is characterized by typical low density, delicate structural appearance and strong wax-glass luster combination, which is inconsistent with the characteristics of natural turquoise and can be used as an important auxiliary identification feature of turquoise treated by “porcelain”. The luminescence of turquoise treated by “porcelain” under long-wave and short-wave UV fluorescence is nearly consistent with natural turquoise. Under microscopic observation, the white melting matter often appears in the iron wire and crevasses, and hair-like crystals can be seen in the pores. The main chemical composition of “porcelain-added” turquoise is similar to the natural turquoise, with CuO, Al₂O₃ and P₂O₅ as the main components, and containing a certain amount of FeOT, ZnO, SiO₂, K₂O and CaO. Among them, the SiO₂ content of the “porcelain-added” turquoise sample is basically above 6.40%, which is higher than that of the natural turquoise (1.96%～6.25%), and its Al₂O₃ and P₂O₅ contents are lower than those of the natural turquoise, and the proportion of phosphorus and aluminum is basically the same as that of the natural turquoise, about 1.10. The high content of SiO₂ and surface feature in turquoise can be effectively distinguished from natural turquoise by “adding porcelain”. The infrared absorption spectrum of turquoise treated by “adding porcelain” is basically the same as that of natural turquoise, which is difficult to distinguish. The Ultraviolet absorption spectrum of turquoise treated by “porcelain addition” shows the absorption peak at 620～750 nm and the relatively sharp absorption peak near 425 nm. The peak positions are slightly shifted due to different colors, but the overall UV absorption spectrum characteristics are consistent with those of natural turquoise.

Key words：“Porcelain-added” treatment of turquoise; Infrared absorption spectrum; Chemical composition; Ultraviolet absorption spectrum; Gemmological characteristic

Received: 2020-01-08 Accepted: 2020-05-12

ZTFLH:

P575.4

Corresponding Authors: CHEN Quan-li E-mail: chenquanli_0302@163.com

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2021)07-2245-06 OR https://www.gpxygpfx.com/EN/Y2021/V41/I07/2245