四川汶川“龙溪玉”的宝石学特征及成因初探  

A Preliminary Study on the Gemmological Characteristic and Formation of“Longxi Yu”in Wenchuan,Sichuan Province

作　　者：白洞洲 张跃峰 丘志力 杨炯 王方[2] 段董念 BAI Dongzhou;ZHANG Yuefeng;QIU Zhili;YANG Jiong;WANG Fang;DUAN Dongnian(School of Earth Sciences and Engineering/Guangdong Key Laboratory of Geodynamics and Geological Hazards/Guangdong Key Laboratory of Geological Processes and Mineral Resources Exploration,Sun Yat-sen University,Zhuhai 519000,China;Chengdu Jinsha Site Museum,Sichuan Chengdu 610091,China;School of Tourism,Taishan College,Taian 271000,China;College of Earth Sciences/Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,Guilin University of Technology,Guilin 541006,China)

机构地区：[1]中山大学地球科学与工程学院/广东省地球动力作用与地质灾害重点实验室/广东省地质过程与矿产资源探查重点实验室,广东珠海519000 [2]成都金沙遗址博物馆,四川成都610091 [3]泰山学院旅游学院,山东泰安271000 [4]桂林理工大学地球科学学院/广西隐伏金属矿产勘查重点实验室,广西桂林541006

出　　处：《宝石和宝石学杂志（中英文）》2022年第3期1-9,共9页Journal of Gems & Gemmology

基　　金：国家自然科学基金项目(41673032)“肃北战国-汉代古采矿遗址(群)软玉:深部地质过程响应及其对丝绸之路华夏早期玉石文明的影响”;山东省自然科学基金面上项目(ZR2015DM008)“山东大汶口文化蛇纹石质玉器产地来源及其与泰山玉关系研究”部分资助。

摘　　要：四川汶川“龙溪玉”被认为是我国著名“三星堆遗址”“金沙遗址”古玉器玉料的可能来源。采用宝石学常规测试、傅里叶变换红外光谱、拉曼光谱、X射线荧光光谱等分析测试方法,对汶川产出典型“龙溪玉”样品的谱学特征及化学成分进行了测试,获得以下认识:(1)“龙溪玉”的折射率为1.61(点测),相对密度为2.95~2.99;“龙溪玉”可分为A和B两种不同的类型,A型黄绿色、质地纯、油脂光泽,以毛毡状交织结构为主,层理构造明显,质优者透闪石含量可达98%以上;B型以灰白夹杂灰黑色为主,质地较粗,丝绢-玻璃光泽,纤维状交织和叶片状定向结构为主,透闪石含量在70%~90%,含碳酸盐矿物等次要矿物,两类均属透闪石质玉;(2)“龙溪玉”样品的红外光谱、拉曼光谱与标准透闪石光谱特征峰一致,存在特殊的微量辉钼矿、钼铅矿等矿物包裹体,但B型料红外吸收光谱存在额外的1446 cm^(-1)吸收峰,表明样品含较多碳酸盐矿物;(3)化学成分特征显示,“龙溪玉”样品中Na_(2)O的含量与中酸性岩浆岩和镁质大理岩/白云质灰岩接触交代形成的透闪石玉类似,成玉过程有明显的热液参与,其中,B型料CaO含量、烧失量明显偏高,具有R型玉的特点;而A型玉料矿物组成单一、结构细腻,类似于P型玉。根据和国内其它产地闪石玉的化学成分特征的比较,初步认为高MnO和高P_(2)O_(5)可能是“龙溪玉”重要的主量元素产地标型特征之一。上述结果可为古玉溯源研究提供重要的参考。The“Longxi Yu”in Sichuan Province is considered to be the possible source of the ancient jade materials of the famous“Sanxingdui site”and“Jinsha site”in China.In this paper,the spectral characteristics and chemical compositions of typical“Longxi Yu”produced in Wenchuan,Sichuan Province were tested by conventional gemmological tests,Fourier transform infrared spectrometer,Raman spectrometer,X-ray fluorescence spectrometer,etc.The following conclusions are obtained:(1)The refractive index of the samples is 1.61(point measurement)and the relative density is 2.95-2.99,which is consistent with nephrite.Two kinds of“Longxi Yu”with high and low quality can be identified as type A and type B.The type A samples are with yellowish green colour,grease luster,pure in quality with fine texture,and the content of tremolite can reach 98%.The type B samples are gray-white mixed with gray-black in colour and mainly composed of tremolite(70%-90%)with a small amount of carbonate and other minor minerals.The type B samples are mainly coarse texture,silk-glass luster,fibrous interleaving and leaf-oriented structure,with obvious bedding structure.Both types of samples are classified as nephrite.(2)The infrared spectra and Raman spectra of“Longxi Yu”samples are consistent with standard tremolite spectrum.And trace minerals such as molybdenite and molybdenite are first reported.The infrared spectra of type B samples show a spectrum peak of 1446 cm^(-1),which is attributed to carbonate.(3)The chemical content of Na_(2)O of“Longxi Yu”is similar to that of nephrite formed by contact metasomatism between intermediate-felsic rocks and magnesia marble/dolomitic limestone,in which there is obvious hydrothermal participation in the forming process of“Longxi Yu”.However,the contents of CaO and loss on ignition(LOI)of the type B samples are obviously higher than that of general nephrite,which can be determined as replacement forming nephrite(R-type nephrite).Meanwhile,type A samples have a simple mineral component

关 键 词：透闪石 宝石学特征 成因类型 成分标型 龙溪玉 四川汶川 

分 类 号：TS93[轻工技术与工程]