Gemmological Characteristic of Petrified Wood from Qitai, Xinjiang and Pagan, Burma
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摘要: 采用常规宝石学测试方法及偏光显微镜、扫描电子显微镜、电子探针、X射线粉末衍射仪等测试手段，对中国新疆奇台及缅甸蒲甘的硅化木样品，从显微结构、宝石学及矿物学特征等方面进行测试与分析。结果表明，本次研究所测试的两地硅化木样品主要矿物组成均为石英（SiO2占总质量分数的90%以上），微晶-显微隐晶质结构，其他矿物的质量分数较低。通过对石英结晶度计算和扫描电子显微镜下石英颗粒形态特征观察，发现缅甸蒲甘硅化木样品的石英结晶度明显高于中国新疆奇台硅化木样品。此外，通过手标本观察、偏光显微镜及扫描电子显微镜下观察，发现新疆奇台硅化木样品中透明度较好的区域，石英颗粒呈放射状或为纤维状玉髓，颗粒较小；而透明度较差的区域，石英颗粒呈柱状、粒状等形态，颗粒之间结合不够紧密。缅甸蒲甘硅化木样品整体均不透明，石英颗粒呈粒状，粒度较大，尺寸在微米级别。Abstract: Conventional gemmological methods, polarizing microscope, scanning electron microscope(SEM), electron microprobe analysis(EMPA), X-ray powder diffraction(XRD) were carried out to obtain the microstructures, gemmological and mineralogical characteristics of petrified wood samples from Pagan, Burma and Qitai, Xinjiang, China. The result shows that the petrified wood samples from two regions consist of quartz (account for over 90% SiO2), which is microcrystal to nanocrystal, and other minor minerals (such as pyrite, dolomite, clay mineral). Through calculating the crystalline index of quartz, together with observing the quartz morphology under scanning electron microscope, the quartz in petrified wood from Pagan, Burma, shows significantly higher crystallinity than that from Qitai, Xinjiang, China. In addition, in the petrified wood from Qitai, Xinjiang, the semitransparent part is fine radial quartz particles or fibrous chalcedony, but the slightly transparent part is granular quartz particles which are not compact. The wholly opaque petrified wood from Burma is granular quartz whose size is at the micron level.
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Keywords:
- petrified wood /
- microstructure /
- Qitai, Xinjiang /
- Pagan, Burma
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