缅甸翡翠化学成分的变化对其红外光谱的影响
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摘要
缅甸翡翠是以硬玉为主要矿物的多晶集合体,硬玉的晶体化学成分可以用NaAlSi2O6来表示,天然产出的硬玉常常存在类质同象替代,Na被Ca替代,Al被Mg,Fe,Cr等元素替代,形成不同的翡翠类型,使得翡翠的化学成分变得更加复杂,而且其物理性质也产生变化,这种变化包括颜色、透明度、折射率、比重、结晶程度以及红外吸收光谱的特征。探索了翡翠的化学成分对其红外光谱的影响及规律,使用傅里叶红外光谱仪(Fourier transform infrared spectroscopy,FTIR)对10个含不同化学成分的缅甸翡翠样品进行漫反射法测量,分析结果表明,翡翠的红外吸收峰的位置随着样品的Na/Na Ca的摩尔比例增加而向高波数发生位移;在低波数区域,在424,576和658cm-1附近的吸收峰位的波数与Na/Na Ca比值存在很好的线性相关,相关系数依次为R21=0.944 2,R22=0.928 3,R23=0.909 7。采用红外光谱测试技术结合所建立的线性模型可以推断未知翡翠样品的Na/Na Ca的摩尔比例,当翡翠样品的Na/Na Ca比值等于0.8时,红外吸收峰应该在658.7,574.5,422.5cm-1处;如果翡翠样品的红外吸收峰波数<658.7,<574.5cm-1,422.5cm-1,则翡翠样品的Na/Na Ca比值大于0.8,为硬玉质翡翠。该工作为红外光谱技术测量翡翠样品,分析翡翠化学成分,确定翡翠矿物种属提供了一种快捷、省时、方便的无损测量分析方法。
Myanmar jade is crystalline aggregate with the major mineral of jadeite.Jadeite can be represented by the crystalchemical formula NaAlSi2O6.Isomorphous substitution occurs in the natural jadeite frequently,with replacement of Na by Ca,and replacement of Al by Mg,Fe,Cr etcetera,which makes the component of Myanmar jade much more complex and leads to the variation of its physical features,including color,transparency,refractive index,specific gravity and infrared spectrum characteristics,forming different types of Myanmar jade.The studies show that the vibrational spectra characteristics of the Myanmar jade varies depending on the substitution of different elements.In this work,we studied the impacts of the variation of Myanmar jade component on its infrared spectroscopy.10 Myanmar jade samples which consisted of different chemical composition were measured using Fourier Transform Infrared Spectroscopy(FTIR),and results show that the IR absorption peaks shift to higher wave numbers,as the atomic ratio of Na/Na Ca of the samples increases.In the low wave number region,the wave number of the IR absorption peaks at 424,576 and 658cm-1 and the atomic ratio of Na/Na Ca of the samples share fine linear correlation,and the correlation coefficients(R2)are,in order,R21=0.944 2,R22=0.928 3,R23=0.909 7.We can utilize infrared spectrum technologies combined with linear model built by us in this work to predicate the atomic ratio of Na/Na Ca of the unknown Myanmar jade samples.As the atomic ratio of Na/Na Ca of the unknown Myanmar jade samples equals 0.8,the IR absorption peaks should be at 658.7,574.5,422.5cm-1.If the wavenumbers of the IR absorption peaks are less than 658.7,574.5and 422.5cm-1,the atomic ratio of Na/Na Ca of the unknown Myanmar jade samples is less than 0.8,which is indicating that the unknown Myanmar jade sample isomphacitic jade,while the wavenumbers of the IR absorption peaks are more than658.7,574.5and 422.5cm-1,the atomic ratio of Na/Na Ca of the unknown Myanmar jade samples is more than 0.8,which is indicating that the unknown Myanmar jade sample is jadeitic jade.The studies of this work offer a super-quick time-saving and labor-saving nondestructivetesting method for using infrared spectrum technologies to test Myanmar jade samples,analyze their component and predicate which mineral styles the unknown samples are.
Myanmar jade is crystalline aggregate with the major mineral of jadeite.Jadeite can be represented by the crystalchemical formula NaAlSi2O6.Isomorphous substitution occurs in the natural jadeite frequently,with replacement of Na by Ca,and replacement of Al by Mg,Fe,Cr etcetera,which makes the component of Myanmar jade much more complex and leads to the variation of its physical features,including color,transparency,refractive index,specific gravity and infrared spectrum characteristics,forming different types of Myanmar jade.The studies show that the vibrational spectra characteristics of the Myanmar jade varies depending on the substitution of different elements.In this work,we studied the impacts of the variation of Myanmar jade component on its infrared spectroscopy.10 Myanmar jade samples which consisted of different chemical composition were measured using Fourier Transform Infrared Spectroscopy(FTIR),and results show that the IR absorption peaks shift to higher wave numbers,as the atomic ratio of Na/Na Ca of the samples increases.In the low wave number region,the wave number of the IR absorption peaks at 424,576 and 658cm-1 and the atomic ratio of Na/Na Ca of the samples share fine linear correlation,and the correlation coefficients(R2)are,in order,R21=0.944 2,R22=0.928 3,R23=0.909 7.We can utilize infrared spectrum technologies combined with linear model built by us in this work to predicate the atomic ratio of Na/Na Ca of the unknown Myanmar jade samples.As the atomic ratio of Na/Na Ca of the unknown Myanmar jade samples equals 0.8,the IR absorption peaks should be at 658.7,574.5,422.5cm-1.If the wavenumbers of the IR absorption peaks are less than 658.7,574.5and 422.5cm-1,the atomic ratio of Na/Na Ca of the unknown Myanmar jade samples is less than 0.8,which is indicating that the unknown Myanmar jade sample isomphacitic jade,while the wavenumbers of the IR absorption peaks are more than658.7,574.5and 422.5cm-1,the atomic ratio of Na/Na Ca of the unknown Myanmar jade samples is more than 0.8,which is indicating that the unknown Myanmar jade sample is jadeitic jade.The studies of this work offer a super-quick time-saving and labor-saving nondestructivetesting method for using infrared spectrum technologies to test Myanmar jade samples,analyze their component and predicate which mineral styles the unknown samples are.
引文
[1]Rossman G R.America Mineralogist,1974,59:868.[2]XIE Yi-hong,WANG Cheng-yun(谢意红,王成云).Rock and Mineral Analysis(岩矿测试),2003,22(3):183.[3]ZHU Wei-shan,HUANG Zuo-liang,KOU Da-ming(朱薇珊,黄作良,寇大明).Liaoning Geology(辽宁地质),2000,17(2):159.[4]SHEN Ke-ya(申柯娅).Chinese Journal of Spectroscopy Laboratory(光谱实验室),2000,17(3):348.[5]Htein W,Naing A M.Journal of Gemmology,1995,24(5):317.[6]QI Li-jian(亓利剑).Journal of Gems&Gemmology(宝石与宝石学杂志),2005,7(4):24.[7]GAO Yuan(高媛).Infrared Technology(红外技术),2008,30(7):427.[8]YUAN Xin-qiang,QI Li-jian,ZHENG Nan(袁心强,亓利剑,郑南).Journal of Gems&Gemmology(宝石与宝石学杂志),2005,7(4):19.[9]WU Shu-qi,GUO Li-he(吴淑琪,郭立鹤).Rock and Mineral Analysis(岩矿测试),1997,16(4):250.[10]ZHANG Bei-li,GAO Yan,AO Yan(张蓓丽,高岩,奥岩).Journal of Gems&Gemmology(宝石与宝石学杂志),1999,1(4):4.[11]CUI Shuo-jing,ZHAO Ting-he,YAN Xue-wei,et al(崔硕景,赵廷河,阎学伟,等).Journal of High Pressure Physics(高压物理学报),1994,8(2):99.[12]ZHAO Kai-ming(赵开明).Yunnan Geology(云南地质),2002,21(2):159.[13]YUAN Xin-qiang(袁心强).Applied Gemology of Myanmar Jade(应用翡翠宝石学).Wuhan:China University of Geosciences Press(武汉:中国地质大学出版社),2009.62.