Spectroscopy and Spectral Analysis, Volume. 45, Issue 1, 183(2025)

Study on Spectral Characteristics of Turquoise Imitations of Single and Multiple Component Mixtures

YANG Chi-yu... WANG Tian-tian*, ZHANG Wei-xiao and TANG Wei-xi |Show fewer author(s)
Author Affiliations
  • Tongji Zhejiang College, Jiaxing 314051, China
  • show less

    Raman spectra, infrared spectra, chemical composition analysis, and UV-Vis NIR spectra analysis were carried out for new turquoise imitations in gem wholesale markets. The main spectral characteristics were summarized. The results show that the imitations are mainly composed of a single component or multiple mixed components of barite, gibbsite, and calcite powder, which are pressed, cemented by epoxy resin or acrylate, and dyed. The infrared spectra results are as follows: The imitations of a single mineral component are significantly different from turquoise. The imitation of barite shows a 1 078 cm-1 absorption peak caused by[SO42- asymmetric stretching vibration and the imitation of calcite shows a 1 476± cm-1 absorption peak caused by[CO32- symmetric stretching vibration. The multi-component imitations can be seen to integrate the absorption spectra of various mineral characteristics, the spectral characteristics are complex. According to the missing water peak, or only showing the absorption peaks of 3 623, 3 528, 3 472, and 3 388 cm-1 caused by the stretching vibration of OH- of gibbsite, and there are[SO42- and[CO32- groups correlated absorption peaks in the fingerprint region, we can roughly distinguish the imitations from turquoises. The micro-Raman spectra show that the mineral compositions of the multi-component imitations are different at different test locations, and the characteristic peaks of gibbsite (3 360,3 432,3 522,3 614 cm-1), barite (989 cm-1)and calcite (1 088 cm-1)can be measured respectively. Combined with the results of micro-Raman spectra and chemical analysis, the specific mineral composition of the imitation product can be further confirmed. The UV-Vis-NIR spectra show that the samples are dyed and showed 633± nm, 713± nm or 610± nm, and 675± nm broad absorption peaks.

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    YANG Chi-yu, WANG Tian-tian, ZHANG Wei-xiao, TANG Wei-xi. Study on Spectral Characteristics of Turquoise Imitations of Single and Multiple Component Mixtures[J]. Spectroscopy and Spectral Analysis, 2025, 45(1): 183

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    Paper Information

    Received: Dec. 26, 2023

    Accepted: Feb. 28, 2025

    Published Online: Feb. 28, 2025

    The Author Email: Tian-tian WANG (1468586297@qq.com)

    DOI:10.3964/j.issn.1000-0593(2025)01-0183-08

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