Nondestructive analysis of Lantian jade from Shaanxi Province, China

Lantian jade is a kind of ancient Chinese jades. The modified external-beam proton-induced X-ray emission (PIXE), X-ray diffraction (XRD), laser Raman spectroscopy (LRS) and the scanning electron microscopy (SEM) were employed to analyze the chemical and mineral composition of the modern Lantian jade from Shaanxi Province. The jade samples can be categorized into two classes. The first class consists of mainly of antigorite and the level of serpentinization is high. One sample exhibited Raman characteristic bands of lizardite, a serpentine mineral which was described for the first time in Lantian jade. Therefore, Lantian jade can be further subdivided into Lantian antigorite jade and Lantian lizardite jade, which can be distinguished from each other by the XRD and Raman spectra. The second class consists mainly of calcite, serpentine and augite, with traces of talc, dolomite and tremolite. Also Mn, Zn and Zr contents are higher compared to the other trace elements. Lantian jade formed when dolomitic marble was converted to serpentine minerals by magmatic hydrothermal metasomatism at low temperature. These characteristics can provide useful data for archeological research on Lantian jade.