HAN Wen1, LIU Yang2, ZHANG Jun1, LU Tai-jin1
(1. National Gems & Jewelry Administrative Centre, Beijing 100013, China;
2. Pingzhou Lab, National Gemstone Testing Centre, Foshan 528251, China)
Abstract: The Lavender Jadeite Jade is an important variety of natural jades, with high economic value. There are two types of lavender jadeites, including the pure purple one and bluish purple one. In this paper, besides methods of traditional spectroscopy and chemical analysis, Electron Paramagnetic Resonance (EPR) and X-ray Photoelectron Spectroscopy (XPS) were specifically used to investigate the color origins and chemical valences of the chromogeneic elements of two types of lavender Jadeite jades. The results show that colors of both two types of lavender jadeites were caused by the jadeite particles themselves. For the pure purple jadeite jade, the color is related to the contained Mn (w(MnO)：0.0035%－0.036%) which causes the 580 nm absorption band of UV-VIS, mainly in form of Mn3+ rather than Mn2+ based on the EPR results. Both Fe and Ti (w(FeO)：0.039%－0.25%; w(TiO2)：0.018%－0.17%) resulted in the bluish purple color of the second lavender jadeite jade. The XPS analysis suggests that the major chromogenic cations are Fe2+, Fe3+, and Ti4+. It is believed that the Fe2+-Ti4+ and Fe2+-Fe3+ charge-transfers are responsible for the bluish purple coloration which causes the 530 and 610 nm absorption bands of UV-VIS.
Keywords: Lavender jadeite jade; electron paramagnetic resonance; X-ray photoelectron spectroscopy; color origin
ACTA MINERALOGICA SINICA Vol. 40, No.5, 2020, page 549-555
