绿松石及其处理品的鉴别研究

Identification of Turquoise and Treated Turquoise

  • 摘要: 绿松石是中国的四大名玉之一,因产量较少、温润而颇受人们喜爱。近些年,由于资源过度开采,品质优良的绿松石日渐稀少,价格逐渐走高。市场上出现了大量质地较差绿松石的处理品。目前,国内外对绿松石的系统鉴定资料较少,因此建立系统简便鉴别天然绿松石、注无/有色胶和Zachery处理绿松石方法对规范宝玉石市场尤为重要。以天然绿松石、注无/有色胶和Zachery处理绿松石为研究对象,通过常规宝石学特征、红外光谱、显微激光拉曼光谱、X射线荧光光谱等测试结果发现,天然绿松石为鲜明的天蓝色、绿色,呈油脂光泽-玻璃光泽;注胶处理绿松石的颜色呆板,呈弱玻璃光泽-蜡状光泽,弱到强的蓝白色荧光,表面有时见胶残留或胶富集,其密度、折射率均比天然绿松石低;Zachery处理绿松石的裂隙两侧有颜色集中现象,密度、折射率与天然绿松石相当。红外光谱测试结果发现,注胶绿松石的红外光谱存在位于2 920cm -1处高分子聚合物中的νas(CH2)不对称伸缩振动谱带和位于2 850cm -1νs(CH2)对称伸缩振动吸收谱带,位于2 960cm -1νas(CH3)不对称伸缩振动谱带,位于1 733cm -1处ν(C=O)伸缩振动谱带,具有鉴定意义。激光拉曼测试结果发现,注胶绿松石位于1 453,1 455cm -1处的CH2弯曲振动弱谱峰可作为其鉴定特征峰。X射线荧光光谱分析显示Zachery处理绿松石中的K元素含量可达4.4%,可能是注入了无机钾盐。

     

    Abstract: Turquoise is one of the four most famous jade in China.Due to its scarcity, quality, and its beautiful appearance, turquoise has been popular with people.In recent years, resource exploitation has made beautiful and good quality turquoise less and less.Therefore, a lot of treated turquoise and imitations appeared on the market.We chose natural turquoise, polymer impregnated turquoise and Zachery treated turquoise as the research objects.We conducted the basic gemmological tests, infrared spectral analysis and laser micro-Raman spectroscopy and X-ray fluorescence spectrometry on these test objects.It is concluded that natural turquoise appears as bright sky blue, green with light oily-vitreous luster, and polymer impregnated turquoise appears as dull colour with weak vitreous-waxy luster, and sometimes one can see polymer residue or polymer enrichment on the surface.Additionally, the density and refractive index of polymer impregnated turquoise is lower than natural turquoise, and the impregnated turquoise appeared with weak to strong blue-white fluorescence.We found that Zachery treated turquoise showed microscopic cracks on both sides of the colour concentration, with the same density, refractive index as natural turquoise.Impregnated turquoise showed infrared spectral characteristics of polymer:ν(as)(CH2) asymmetric stretching vibration band at 2 920cm-1, νs(CH2) symmetric stretching vibration band at 2 850cm-1, and ν(as)(CH3) asymmetric stretching vibration band at 2 960cm-1 and infrared absorption band at 1 733cm-1 caused by ν(C=O) stretching vibration can be used for identification.According to laser Raman spectra, the weak spectrum peaks at 1 455, 1 453cm-1 of CH2bending vibration can be used to identify polymer impregnation processed turquoise.X-ray fluorescence spectroscopy showed K element content of Zachery treated turquoise can reach 4.4%.

     

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