摘要
对澳大利亚某矿区蓝宝石样品的宝石学和谱学特征进行研究,并为该矿区蓝宝石的优化处理工艺提供理论依据。采用常规宝石学仪器、傅里叶红外光谱仪,激光剥蚀等离子体质谱仪、显微紫外-可见分光光度计和激光拉曼光谱仪等对澳大利亚蓝宝石样品的宝石学特征、化学成分、红外光谱、拉曼光谱、紫外-可见光谱进行了系统研究。结果表明,澳大利亚蓝宝石样品的颜色分布不均匀,普遍发育六边形平直生长色带,其包裹体主要包括二相包裹体(CO_2和H_2O)、蓝宝石、金红石、锆石、硬水铝石、角闪石等;红外光谱中3 310 cm^(-1)处的吸收峰指示着该矿区蓝宝石生长于还原条件下,其Cr/Ga比值小于1且Fe/Ti比值大部分介于10～100,为典型岩浆岩型蓝宝石的比值;澳大利亚蓝宝石样品的颜色主要与Fe、Ti、Si、Mg等元素质量分数有关:Ti质量分数较少的区域常出现由Fe^(3+)离子的d-d电子跃迁导致的377、387、450 nm处的吸收峰;而Ti质量分数较多的区域常出现由Fe^(2+)—Ti^(4+)离子对电荷转移导致的以559 nm为中心的黄绿区的吸收带;Fe^(2+)—Fe^(3+)离子对电荷转移常常与Fe^(2+)—Ti^(4+)离子对电荷转移同时出现并导致以754 nm附近为中心的700～800 nm处的宽缓吸收带,且根据Fe^(2+)—Fe^(3+)、Fe^(2+)—Ti^(4+)离子对电荷转移的比例不同,吸收带的中心会发生偏移。
Australia is a major producer of sapphire.The main purpose of this study is to analyze the gemmological and spectrcal characteristics of sapphire samples from Australia,and to provide a theoretical basis for the treatment of sapphires.The gemmological and spectral characteristics of sapphire samples from Australia were studied by using the conventional gem test,Fourier transform infrared spectroscopy(FTIR),laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS),micro-ultraviolet-visible spectroscopy(UV-Vis)and laser Raman spectroscopy.The result showed that the specific gravity of sapphire samples from Australia is 3.74-4.20,N e=1.762-1.770,N o=1.770-1.778,DR=0.008,and strong glass gloss and inertia under ultraviolet fluorescent lamp.Blue and yellow hexagonal colour zone,healing fissures and inclusions are extremely common in sapphire sample from Australia,where have kinds of solid inclusions,two-phase inclusions and healing fissures.Infrared peaks such as 630,519,490,454,436 cm^-1 in the fingerprint region,and absorption peak at 3 310 cm^-1 indicated that these sapphires from Australia grew in reducing condition.The chemical composition and geological origin by LA-ICP-MS,showed that the Cr/Ga ratio is less than 1 and the Fe/Ti ratio is mostly between 10-100,which is the ratio of typical magmatic sapphire,and the iron content is between 3 230×10^-6-9 431×10^-6.Comprehensive analysis of UV-Vis absorption spectroscopy and chemical compositions turns out that the colour is mainly relevant to the content of Fe,Ti,Si,Mg.Absorption peaks of 377,387 and 450 nm are caused by the d-d electronic transition of Fe^3+and Fe^3+-Fe^3+in the region with less Ti;Fe^2+-Ti^4+charge transfer leads to the yellow green region absorption band centered at 559 nm in the region with multiple Ti;Fe^2+-Fe^3+charge transfer often occurs with Fe^2+-Ti^4+charge transfer,and causes the wide absorption band in 700-800 nm centered in 754 nm,center may shift with different ratio of the charge transfer of Fe^2+-Fe^3+and Fe^2+-Ti^4+.Raman spectroscopy showed that the inclusions mainly include two-phase inclusion(CO 2 and H 2 O),sapphire,rutile,zircon,diaspore,amphibole and so on,sulphur on healing fissures means that S element participated in the transaction of sapphire.
作者
徐娅芬
狄敬如
方菲
XU Yafen;DI Jingru;FANG Fei(Gemmological Institute, China University of Geosciences, Wuhan 430074, China)
出处
《宝石和宝石学杂志》
CAS
2019年第2期24-33,共10页
Journal of Gems & Gemmology
基金
国家重点研发计划(2018YFF0215400)
中国地质大学(武汉)珠宝学院科研基金项目(CIGTXM-S201713
CIGTWZ-2018015)
关键词
蓝宝石
宝石学特征
谱学特征
颜色成因
包裹体
澳大利亚
sapphire
gemmological characteristic
spectral characteristic
colour origin
inclusion
Australia
