机构地区:[1]中山大学地球科学与工程学院广东省地质过程与矿产资源探查重点实验室广东省地球动力作用与地质灾害重点实验室
出 处:《光谱学与光谱分析》2020年第3期956-960,共5页Spectroscopy and Spectral Analysis
基 金:国家自然科学基金项目(41673032,41173041)资助
摘 要:石英质玉分布广泛,在我国十几个省区均有产出,是国内市场上重要的特色玉石品种,其使用历史悠久,是岭南先秦时期重要的玉石材料。石英质玉石的产地区分具有重要的宝石学和考古学意义。然而,由于石英质玉产地众多,外观、成分特征相似,尚缺乏有效的产地判别方法,其产地来源标型特征的研究仍然非常薄弱。"台山玉"是产于广东台山的一种石英质玉石,因其颜色质感酷似田黄而日益受到重视。该研究在常规的宝石学测试基础上,采用X射线粉末衍射(XRD)、傅里叶变换红外光谱(FTIR)、显微激光拉曼光谱(Raman)等分析方法,对6件具有代表性不同类型的台山玉的谱学特征及矿物组成进行了测试分析。实验结果显示,台山玉主要矿物为石英,次要矿物为地开石或高岭石;地开石、高岭石在台山玉中以其中一种为主,二者不共存;利用XRD-Rietveld法定量计算出台山玉中石英含量低于85 Wt%,高岭石族矿物含量介于17 Wt%~36 Wt%。台山玉的拉曼光谱缺失斜硅石的502 cm^-1特征峰,暗示了台山玉的主要矿物石英与玉髓、玛瑙类低温石英相比具有较高的结晶度;台山玉可分为地开石石英岩玉和高岭石石英岩玉两种类型,其中地开石型石英质台山玉红外光谱羟基振动区出现3 622, 3 653和3 703 cm^-1三个谱带,而拉曼光谱相应地出现3 622, 3 644和3 706 cm^-1三个谱带,二者均有谱带分裂明显,峰强向高频方向递减的特点,台山玉多为此类型;高岭石型台山玉红外光谱羟基振动区出现3 620, 3 652, 3 670和3 695 cm^-1四个谱带,而拉曼光谱出现3 620, 3 651, 3 670和3 687 cm^-1四个谱带,其中3 670 cm^-1带强度很弱,不易识别,该类型台山玉比例相对较少。台山玉中高有序度地开石、高岭石的出现指示其原岩中富Al质矿物经历了中温酸性热液交代蚀变作用,成矿条件与黄龙玉、金丝玉、霍山玉等石英岩玉存在差异。可以确定,Quartzose jade, which is widely distributed and has been mined in more than 10 provinces and regions in China, is an important characteristic jade in the domestic market. It has been used for thousands of years and wasthe predominant jade material inthe pre-Qin period of Lingnan area. The origin distinction of quartzose jade is of great significance in gemology and archaeology. However, due to the similar appearance and composition characteristics for quartzose jades from different mines, there is still a lack of effective origin discrimination methods for quartzose jades, and the study on the origin typomorphic characteristics of quartzose jade is still very weak. Taishan jade, produced in Taishan, Guangdong Province, is a kind of quartzose jade increasingly valued for its Tianhuang-like appearance. On the basis of conventional gemological tests, the spectral characteristics and mineral composition of 6 representative samples of Taishan jade were studied by using X-ray powder diffraction spectrometer(XRD), Fourier transform infrared spectrometer(FTIR) and Raman spectrometer. The results showed that the main mineral of Taishan jade is quartz and the minor mineral is dikite or kaolinite, with other minerals spectroscopycally undetectable. The two kinds of kaolin group minerals do not coexist in Taishan jade. Based on the XRD-Rietveld quantitative analysis, the content of quartz in Taishan jade is less than 85 Wt%, while the content of kaolin group mineralsis between 17 Wt% and 36 Wt%. The absence of 502 cm^-1 band, which is the diagnostic Raman band for moganite, in the Raman spectra of Taishan jade indicates that the quartz in Taishan jade has a higher crystallinity than the quartz formed at low temperature, such as chalcedony and agate. Taishan jade can be divided into two types: dickite quartzose jade(the main type) and kaolinite quartzose jade(the secondary type). The infrared spectra of dickite quartzose Taishan jade showed three intense OH-stretching bands at 3 622, 3 653 and 3 703 cm^-1, while the Raman spe
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