应用X射线衍射－激光拉曼光谱－电子探针等分析测试技术研究旬阳朱砂玉的矿物学特征

摘要

近年来外观形似鸡血石的红色朱砂玉备受关注，其中吉林、贵州、青海等地这种红色岩石已有矿物成分、岩性等相关方面的研究。本文利用常规宝石常数测定手段（偏光显微镜）、X射线粉晶衍射、激光拉曼光谱、电子探针等分析测试技术，对陕西旬阳朱砂玉的矿物学和宝石学特征进行了研究。结果表明，该产地朱砂玉的矿物成分以石英、辰砂为主，含有少量的方解石、白云石、重晶石、黄铁矿；其中主要矿物成分辰砂的颜色随铁含量的增加而逐渐加深；矿物结构以碎屑结构、粒状变晶结构、穿插交代结构为主。根据矿物成分以及矿床成因的研究分析，初步认为陕西旬阳朱砂玉属于沉积－热液－强烈改造型矿床。该地区的朱砂玉与鸡血石的相似之处在于矿物的主要成分都含有辰砂，致使外观品质上具有一定的相似性，但具体矿床成因以及矿物成分有着明显的差别：旬阳朱砂玉产于沉积－热液－强烈改造型矿床中，其“地”主要矿物成分为石英岩，“血”为辰砂；而浙江昌化和内蒙古巴林鸡血石均产于中生代交代蚀变酸性火山岩的次级断裂小构造中，其“地”主要为地开石、高岭石、叶腊石，“血”为辰砂。此次研究采用多种分析测试手段为旬阳朱砂玉与鸡血石的鉴别提供了可靠的依据。%In recent years,due to the similar appearance of Chicken-blood stone,red cinnabar jade has been a research concern of mineral composition,lithology and other related aspects in Jilin,Guizhou,Qinghai and other places.To investigate this further,mineralogical and gemological research has been conducted on cinnabar jade in Xunyang, Shannxi Province,by means of conventional gemstone constant determination method (Polarizing Microscope ),X-ray Powder Diffraction (XRD),Laser Raman Spectroscopy (LRS)and Electron Probe.The main mineral compositions of the samples are quartz and cinnabar,with minor calcite,dolomite,barite and pyrite.The color of cinnabars becomes darker with the increase of iron content.The mineral textures are mainly clastic,granular and interpenetration metasomatic.Both the red cinnabar jade samples and bloodstone contain cinnabar,leading to their similarity in appearance.Moreover,there are obvious differences in deposit genesis and mineral composition between them.Cinnabar jade in Xunyang belongs to sedimentary-hydrothermal-strongly alteration ore deposit.The matrix of the samples is quartz, and the phenocryst is cinnabar.Chicken-blood stone of Changhua in Zhejiang Province and Balin in Mongolia Province are found in secondary fractures of Mesozoic metasomatic acidic volcanic rocks and the matrix minerals are dickite, kaolinite and pyrophyllite,with the same phenocryst of cinnabar as the samples used in this study.The multi-analytical techniques used in this study provide the reliable basis for identification of Xunyang cinnabar jade and chicken-blood.