两种新型仿孔雀石材料的宝石学特征

Gemmological Characteristic of Two New Malachite Imitations

  • 摘要: 针对近期瑞丽珠宝市场上出现的两种新型仿孔雀石材料,采用常规宝石学测试手段、红外光谱、紫外-可见光谱、X射线粉末衍射等方法对其基本性质、纹理形态、物相组成、谱学特征进行分析,并与天然孔雀石及早期仿孔雀石材料作对比研究。结果表明,两种仿制品均属于环氧树脂粘合的压制碳酸盐类,仿制品A以方解石为主,含部分白云石及很少量重晶石,质地较粗,色泽黯淡,具二色纹带。仿制品B为纯的方解石,质地细腻、色泽明艳、具三色纹带。这两种仿制品以其不规则的多变纹带、颜色组合、折射率、相对密度、硬度等基本特征可与孔雀石区分开来。相比早期的孔雀石仿制品,此二者碳酸盐(方解石、白云石)质量分数增加,重晶石组分减少,在物质组分、热针试验、遇盐酸反应等方面更接近天然孔雀石。

     

    Abstract: Two kinds of imitation products of malachite from Dehong Ruili jewelry wholesale market were tested in this paper. We used the conventional gemmological tests, infrared spectroscopy, UV-Vis spectroscopy and X-ray powder diffraction spectrometer to analyze two new types of malachite imitation, including gemmological characteristics, texture feature, mineral components and spectroscopy characteristics, comparing with natural malachite and other early malachite imitations. The results showed that both of the two imitation materials are repressed carbonates.The inorganic composition of malachite imitation sample A is mainly composed of calcite, including partial dolomite and very small amount of barite, which presents granular structure with two colours and dull hue.The malachite imitation sample B is pure calcite and presents fine texture, three colours bands and bright hue.They can be distinguished from malachite by its irregular and variable stripes, characteristic colour combination, low refractive index, relative density and hardness. Compared with the early malachite imitation, the carbonate(calcite, dolomite) content increased, while the barite reduced in the two malachite imitations, therefore they were more similar to natural malachite in material composition, heat needle test and hydrochloric reaction.In addition, infrared absorption spectrum and UV-Visible absorption spectrum can be used as auxiliary basis for distinguish.

     

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