Lantian Jade is one of the most famous jades in Chinese history, but there still exists controversy among researchers in recognition of the difference between modern Lantian Jade and ancient Lantian Jade, and hence the research on mineralogical characteristics of modern Lantian Jade is of great importance in the archaeological study of Lantian Jade.In this paper, the techniques of proton induced X-ray emission (PIXE), X-ray diffraction (XRD) and laser Raman spectroscopy (LRS) were employed to analyze the chemical composition and mineral structure of modern Lantian Jade from Shaanxi Province.The proportions of several samples were estimated.The results indicate that the specimens can be divided into two kinds.The major mineral of the first kind is serpentine, the major mineral of most specimens is antigorite whose Raman characteristic peaks occur at 231, 373, 458, 527, 648, 681 and 1045 cm-1, and the formula of specimen LT2 is Na0.30(Mg5.08, Al0.14, Fe0.26) (Si4.06O10)(OH)8.However, one of the specimens belongs to lizardite whose Raman characteristic peaks occur at 226, 344, 379, 462, 623, 690 and 1098 cm-1, with lizardite being found in Lantian Jade for the first time.The major minerals of the second kind are serpentine, calcite or augite, together with minor dolomite, talc and tremolite.The formation mechanism of Lantian Jade seemed to be regional metamorphism together with contact metasomatic metamorphism.The formation process is as follows: dolomitic marble generated low temperature metamorphic mineral serpentine by magmatic hydrothermal metasomatism at low temperature, with two kinds of specimens corresponding to different serpentinization levels.There are no other minerals in the first kind, because the calcium was moved away by hydrothermal SiO2.The existence of dolomite and calcite in the second kind suggests incomplete serpentinization.In trace elements, the content of Mn, Zn and Zr is higher than that of other rocks.Both Lantian Jade and Xiuyan Jade belong to serpentine jade, but they can' t be distinguished from each other by available technologies.These characteristics can provide useful data for the study of archaeology and civilization of Lantian Jade.%通过外束质子激发X荧光(proton induced X-ray emission,PIXE),X射线衍射(X-ray diffraction,XRD)、激光拉曼光谱(laser Raman spectroscopy,LRS)等技术对现代陕西蓝田玉进行成分、物相和结构分析,并且计算了部分玉石中主要矿物的含量.结果表明样品可分为两类:第1类主要矿物为蛇纹石,其中大部分样品主要矿物为叶蛇纹石,其拉曼特征峰位于231、373、458、527、648、681和1045 cm-1处;另外有1块蓝田玉的主要矿物为利蛇纹石,其拉曼特征峰位于226、344、379、462、623、690、1 098 cm-1处,这是在蓝田玉中首次发现利蛇纹石.第2类主要矿物为蛇纹石、方解石或斜辉石,并含少量白云石、滑石、透闪石.两类样品的蛇纹石化程度不同.微量元素中,Mn、Zn和Zr的含量较高.这些特征为考古学和文明史的研究提供了有益的数据资料.
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