宝石级蓝锥矿宝石学特征及鉴定

Gemmological Characteristic and Identification of Gem-Quality Benitoite

  • 摘要: 蓝锥矿是一种仅产于美国圣贝托尼的稀有宝石,近年来因其独特的蓝紫色而逐渐走进大家视野。为了在日常检验工作中能快速准确的鉴定出蓝锥矿,对12粒刻面蓝锥矿样品及1块蓝锥矿原石矿物标本进行常规宝石学测试,并运用能量色散型X射线荧光光谱仪、紫外-可见光分光光度计、红外光谱仪及拉曼光谱仪等大型仪器进行测试分析。测试结果表明,蓝锥矿抛光面光泽可至亚金刚光泽,常光折射率约为1.757,双折射率大,非常光折射率超过折射仪测试范围;长波紫外光下呈惰性,短波紫外光下强蓝白色荧光;放大检查常见白色发丝状、针状、短柱状固态包裹体。V元素可能为其致色元素之一,但具体机理需进一步研究。红外光谱在453、502、773、942、1 063 cm-1处的特征吸收峰和拉曼光谱在220、575、935 cm-1处的特征吸收峰是蓝锥矿区别于其他蓝色宝石的诊断性鉴定依据。

     

    Abstract: Benitoite is a rare gemstone originated in San Benito County, California, USA, which has gotten more and more attention. In order to identify the benitoite correctly and rapidly, the authors investigated samples with the help of conventional gemmological identification methods and advanced instrumentations including energy dispersive X-ray fluorescence spectrometer, UV-Vis spectrophotometer, Fourier transform infrared spectrometer, and Raman spectrometer. The results showed the polished facet of benitoite is sub adamantine luster, and the refractive index exceed maximum of refractometer. Under short-wave ultraviolet light the benitoite showed strong bule-white fluorescence. It is usually observed that in benitoite there are many hair-like, needle-like, short-cylinder-like solid inclusions. Vanadium perhaps causes the benitoite's blue colour. Fourier transform infrared spectrum results showed strong absorption peaks at 453,502,773,942,1 063 cm-1 and Raman spectrum results showed strong absorption peaks at 220,575,935 cm-1, which are the identification bases of benitoite.

     

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