gems, jade, seal stones, China, Jilin, Changbai jade

Changbai jade is a type of jade ore with significant economic value found within the tuff of the Upper Triassic Changbai Formation of the Mesozoic era in Jilin Province, China. However, the mineral composition of the kaolinite-group minerals in Changbai jade has not previously been definitively identified, and systematic mineralogical and spectroscopic analyses have been lacking. To investigate the mineralogical and spectroscopic characteristics of Changbai jade, this study employed several modern analytical methods, including X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), Fourier-transform infrared absorption spectroscopy (FTIR), Raman spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy. Mineralogical and spectroscopic analyses were conducted on Changbai jade ore samples CB21 and CB22. The results indicate that the principal metamorphic minerals in the two samples are dickite, and that pyrite is the colouring agent responsible for the yellow portions. This research provides fundamental theoretical data for jade-processing technology and for determining the geological origin of Changbai jade.