缅甸抹谷粉色石榴石的宝石学和谱学特征  

Gemmological and Spectral Characteristics of Pink Garnet from Mogok,Myanmar

作　　者：张龙博 林碧菡 万水芸 陈涛[1,2] 张倩 ZHANG Longbo;LIN Bihan;WAN Shuiyun;CHEN Tao;ZHANG Qian(Gemmological Institute,China University of Geosciences,Wuhan 430074,China;Hubei Gems and Jewelry Engineering Technology Research Center,Wuhan 430074,China;National Center for Quality Inspection and Testing of Gem&Gold-Silver Jewelry,Henan Institute of Product Quality Inspection Technology,Zhengzhou 450047,China)

机构地区：[1]中国地质大学(武汉)珠宝学院,湖北武汉430074 [2]湖北省珠宝工程技术技术研究中心,湖北武汉430074 [3]河南省产品质量检验技术研究院国家玉石金银饰品质量检验检测中心(河南),河南郑州450047

出　　处：《宝石和宝石学杂志（中英文）》2023年第3期16-21,共6页Journal of Gems & Gemmology

基　　金：国家自然科学基金面上基金项目(42072252),中国地质大学(武汉)珠宝检测技术创新中心文章编号CIGTWZ-2022007。

摘　　要：采用折射仪等常规宝石学仪器、电子探针(EPMA)、激光剥蚀电感耦合等离子体质谱仪(LA-ICP-MS)、激光拉曼光谱仪、傅里叶变换红外光谱仪和紫外-可见光谱仪对2颗产自缅甸抹谷的粉色石榴石样品进行测试。红外光谱及拉曼光谱表明其属于较纯净的钙铝榴石端元。电子探针测试得到其化学成分均接近钙铝榴石端元,平均晶体化学式分别为Ca_(3.08)(Al_(1.84)Ti_(0.06)Fe_(0.01)Mg_(0.01))_(1.92)[(Si_(2.90)Al_(0.10))_(3.00)O_(12)]和Ca_(3.06)(Al_(1.84)Ti_(0.08)Fe_(0.01)Mg_(0.01))_(1.94)[(Si_(2.91)Al_(0.09))_(3.00)O_(12)]。LA-ICP-MS测试结果表明,2颗粉色石榴石样品均含有Ti、Fe、Zr、Mn、Nb、Ga、Sn等微量元素,相比于颜色相近的墨西哥草莓红钙铝榴石前者Ti含量较高,在5444~10035 ppm,而Mn含量较低,仅有47~132 ppm。紫外-可见吸收光谱结果显示,2颗粉色石榴石样品分别在489 nm和495 nm处有吸收带,均有以550 nm为中心的吸收宽带,结合微量元素测试结果及其他学者对石榴石及其他硅酸盐矿物中Mn离子吸收光谱的研究分析,推测样品的粉红色由Mn 3+导致。In this paper,2 pink garnet samples from Mogok,Myanmar were studied by electron microprobe,laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS),Raman spectrometer,infrared spectrometer and ultraviolet-visible spectrometer and other conventional gemmological tests.Infrared and Raman spectra results indicated that they are close to the grossular endmember.The chemical composition of the samples was tested by electron microprobe.The result also demonstrated that the 2 samples are close to the endmember of grossular.The average chemical structure formulas of the samples G1 and G2 are Ca_(3.08)(Al_(1.84)Ti_(0.06)Fe_(0.01)Mg_(0.01))_(1.92)[(Si_(2.90)Al_(0.10))_(3.00)O_(12)]and Ca_(3.06)(Al_(1.84)Ti_(0.08)Fe_(0.01)Mg_(0.01))_(1.94)[(Si_(2.91)Al_(0.09))_(3.00)O_(12)],respectively.The test result of LA-ICP-MS showed that both samples contain trace elements such as Ti,Fe,Zr,Mn,Nb,Ga and Sn.The content of Ti in the samples,ranging from 5444 to 10035 ppm,is higher than that in raspberry-red grossular from Mexico,while the content of Mn is lower,only 47 to 132 ppm.Ultraviolet-visible spectra analysis revealed that the samples G1 and G2 have absorption bands at 489 nm and 495 nm,respectively.There is an absorption broad band centered at 550 nm in both samples.Combined with the trace elements in the samples and the previous research about the role of Mn in garnet and other silicates,it is believed that the absorption broad bands are related to Mn 3+,which means their colour is probably due to the presence of small amounts of Mn 3+.

关 键 词：粉色钙铝榴石 宝石学特征 谱学特征 颜色成因 缅甸抹谷 

分 类 号：P575[天文地球—矿物学] TS93[天文地球—地质学]