南红玛瑙的宝石学特征

Gemmological Characteristics of Nanhong Agate

  • 摘要: 对南红玛瑙进行常规宝石学测试、能量色散X射线荧光光谱测试和红外光谱测试,旨在总结南红玛瑙的宝石学特征并探索其鉴定方法。结果表明,南红玛瑙的宝石学性质与玉髓基本一致,但也具有独特之处,其原石和成品均有明显胶质感,放大检查发现红色半透明部分中可见颜色由大量红色点状颗粒组成,而红色不透明部分观察不到红色点状颗粒;能量色散X射线荧光光谱仪测试到南红玛瑙中含有大量Si元素,其次为Fe元素及少量K、Ca、Ti、Zn、Cr等元素,因此推测南红玛瑙由Fe3+元素致色,红色半透明部分中红色点状颗粒成分可能为Fe2O3,并且红色鲜艳程度与Fe元素质量分数呈正比;南红玛瑙的红外光谱与玉髓和石英岩的匹配度均很好,因此推断其结构介于隐晶质和显晶质之间,属于石英质向玉髓的过渡阶段。

     

    Abstract: Nanhong agate is studied by using conventional gemmological tests,EDXRF and infrared spectrometer to summarize gemmological characteristics and identification methods.The regular inspection result shows that gemmological characteristics of Nanhong agate are basically similar to those of chalcedony,with only some unique features,such as obvious colloid feeling and red particle structure.Many red particles can be observed in the colour of semitransparent parts by magnification,and it can’t be observed in the red and opaque Nanhong agate samples.EDXRF result shows that the main chemical composition of Nanhong agate is Si with microelectronics such as Fe,K,Ca,Ti,Zn,Cr,etc.It can be concluded that the trivalent Fe3+contributes to red colour of Nanhong agate,and red particles of red semitransparent parts are composed of Fe2O3.In addition,it can be seen that the bright degree of red part is directly proportional to the content of Fe.The results show that infrared spectra of Nanhong agate match well with those of chalcedony and quartz,which reveal that Nanhong agate is transitional phase from quartz to chalcedony agate with the texture between cryptocrystalline and phanerocrystalline.

     

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