中国西北五地天河石矿物与地球化学特征研究

Mineralogical-Geochemical Characteristics of Amazonite from Five Localities in Northwest China

  • 摘要: 天河石是中国古代重要的玉石材料,其产地溯源对于揭示早期资源利用与文化交流具有重要意义。然而,以往研究多局限于单一产地或特定文物的分析,缺乏基于多区域地质背景的系统性对比分析,使不同产地天河石的地球化学指纹特征尚不明确,制约了文物溯源的准确性。本文选取中国西北地区新疆阿勒泰、星星峡国宝山、星星峡白石头泉以及甘肃阿克塞大红山、陕西华阳川5地天河石矿区矿料为研究对象,采用偏光显微镜、X射线粉晶衍射(XRD)、红外光谱与拉曼光谱、电子探针(EPMA)及电感耦合等离子体质谱(ICP-MS)等多种分析手段,系统分析了其矿物学、谱学及元素组成特征,旨在建立可靠的产地判别体系。结果表明:①各产地天河石均由微斜长石和少量钠长石组成,杂质矿物组合可作为初步区分依据;②红外光谱在430 cm−1附近的谱带形态具有产地指示性,星星峡样品呈单一主峰,阿勒泰、大红山等地样品为427 cm−1和448 cm−1双峰;③主微量元素分析显示,Rb含量与K/Rb比值以及稀土元素配分模式相互补充,是有效的产地判别指标。华阳川样品“低Rb,高K/Rb”且具有独特的Eu正异常,星星峡国宝山与白石头泉两地样品“高Rb,低K/Rb”,大红山样品呈明显Ce负异常。本研究揭示了不同产地天河石在矿物学、谱学及元素组成的差异,建立了一套多指标、可量化的天河石产地判别新方法,可应用于西北地区古代天河石文物的来源研究,进而为相关文化交流提供科学依据。

     

    Abstract: Amazonite was a significant gemstone in ancient China, and determining its provenance is crucial for understanding early interregional resource use and cultural exchange patterns. However, previous studies have often been limited to single localities or specific artifacts, lacking systematic multi-regional geological comparisons. This has left the geochemical fingerprint characteristics of amazonite from different sources unclear, hindering the accuracy of artifact provenance studies. This study focuses on five amazonite mining areas in Northwest China: Altay (Xinjiang), Guobaoshan, Baishitouquan (Xingxingxia), Dahongshan (Aksai, Gansu), and Huayangchuan (Shaanxi). Using various analytical techniques, including polarized light microscopy, X-ray powder diffraction (XRD), infrared and Raman spectroscopy, electron probe microanalysis (EPMA), and inductively coupled plasma-mass spectrometry (ICP-MS), the mineralogical, spectroscopic, and elemental composition characteristics of the samples were systematically analyzed, aiming to establish a reliable source identification system. The results show that: (1) Amazonite from all localities consists of microcline with minor albite, though the impurity mineral assemblages allow for preliminary differentiation; (2) Infrared spectral features near 430 cm−1 provide clear provenance indicators: samples from Xingxingxia show a single dominant peak, while those from Altay, Dahongshan, and other localities exhibit split peaks at 427 cm−1 and 448 cm−1; (3) Major and trace element analyses reveal that Rb content, K/Rb ratio, and rare earth element distribution patterns complement each other as effective discriminant indicators. Huayangchuan samples show “low Rb, high K/Rb” and a unique Eu positive anomaly, Xingxingxia samples (from both Guobaoshan and Baishitouquan) exhibit “high Rb, low K/Rb”, and Dahongshan samples show a clear Ce negative anomaly. This study reveals differences in mineralogy, spectroscopy, and elemental composition of amazonite from different localities and establishes a multi-indicator, quantifiable method for source identification. This method can be applied to trace the sources of ancient amazonite artifacts from northwest China, thereby providing scientific support for related studies on cultural exchange.

     

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