四川雅安绿色软玉的宝石矿物学特征  

Gemmological and Mineralogical Characteristics of Nephrite from Ya'an,Sichuang Province

作　　者：金晓婷[1] 丘志力[1] 戴苏兰[2] 易建华 李榴芬[1] 张跃峰[1] 

机构地区：[1]中山大学地球科学与工程地质学院,宝玉石研究鉴定(评估)中心,广东广州510275 [2]四川省产品质量监督检验检测院,四川成都610000 [3]宝兴润东矿业发展有限责任公司,四川雅安625700

出　　处：《宝石和宝石学杂志》2014年第5期1-8,共8页Journal of Gems & Gemmology

基　　金：国家自然科学基金(40073021;41173041);高校基本科研业务费项目(12lgjc13)部分资助

摘　　要：四川雅安地区新近发现一处颇具特色的绿色—浅绿色软玉矿产资源,该软玉在产出状态、外观特征、玉石结构、构造及成矿特点等方面明显有别于国内外同类型软玉矿床。采用X射线粉末衍射仪、扫描电子显微镜、傅里叶变换红外光谱仪及电子探针等测试方法,重点就该类软玉的物相、微组构、振动光谱、微区化学成分等特征进行了分析。观察与测试结果表明,雅安软玉具致密块状构造和典型的纤柱状交织结构,其主要矿物组成为透闪石(95%~98%),还含少量钙铬榴石、铬铁矿及石英等次要矿物;红外吸收光谱显示其吸收谱带数目、峰位均与透闪石标准图谱相吻合;透闪石微区化学成分分析结果显示,雅安软玉相对贫Mg,富Fe,含Cr,其中w(FeOT)=1.810%~2.365%,w(Cr2O3)=0.019%~0.152%,Mg/(Mg+Fe)在0.944~0.957区间内变化,其中Fe、Cr元素可能是导致雅安绿色软玉致色的主要因素。Recently, a distinctive deposit that produces green to light green nephrites has been discovered in Ya~ an, Sichuan Province. This nephrite deposit differs from the others in terms of output state and appearance, as well as nephrite texture, structure and its metallo- genic features. The deposit located at the southeast section of Mount Longmen Fault Zone, Sichuan Province, where fault structure was rich and magmatic actions were developed. Nephrite deposit from Ya ~ an is related to ultrabasic rock clusters, mainly distributing around the contact zone of augite peridotite and marble with stratoid and lentoid output. In general, augite peridotites went through tremolitization, serpentinization, chloritization and sili- eonization to various extents, and alteration zone has a length of 1 to 3 meters without obvi-ous zoning. In this paper, the mineral components, microstructure, spectroscopy, micro ar- ea chemical compositions characteristics of nephrites from Ya＇an were studied through tes- ting methods like X-ray powder diffraction, scanning election microscope, Fourior transform infrared spectrometer and electron microprobe. Combined XRD results with field occurrence and specimen observation, it is suggested that nephrites from Ya＇an are mainly composed of tremolites （95 ~//00~98~）, and a few uvarovites, calcites and chromites, etc. The further ob- servation results from SEM show that crystalline particle of tremolite mineral in nephrite from Ya＇an is relatively big compared with similar nephrites at other deposits home and a- broad. Most particles are in the shape of long columnar and plate columnar, and some parts are of fiber/column shaped interwoven structure distributing along a certain direction. Most particles have a width of about 30 htm, a length about 80 ptm and a thickness about 1 l^m. The particles have no obvious deformation, indicating the nephrites were in a stable environ- ment with rare reformation in the later period. FTIR results show that the numbers of ab- sorption bands and the po

关 键 词：软玉 物相分析 振动光谱 微组构 四川雅安 

分 类 号：P619.28[天文地球—矿床学] TS93[天文地球—地质学]