Color Mechanism of Blue Myanmar Jadeite Jade: The Role of Trace Elements and Mineralogical Characteristics

Myanmar blue jadeite jade is a rare and highly prized gemstone, yet its coloration and formative mechanisms remain poorly understood. In this study, petrographic analysis, ultraviolet–visible (UV–Vis) spectroscopy, electron probe microanalysis (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were performed on a sample of Myanmar blue jadeite with small white blocks to investigate its mineral composition, trace element distribution, and coloration mechanisms. Most of the sample was found to be blue, with surrounding white areas occurring in small ball-shaped blocks. The main mineral component in both the blue and white domains was jadeite. Although both areas underwent recrystallization, their textures differed significantly. The blue areas retained primary structural features within a medium- to fine-grained texture, reflecting relatively weaker recrystallization. The white areas, however, were recrystallized into a micro-grained texture, reflecting relatively stronger recrystallization, with the superimposed effects of external stress producing a fragmented appearance. The blue jadeite had relatively higher contents of Ti, Fe, Ca, and Mg, while the white jadeite contained compositions close to those of near-end-member jadeite. It was noted that, while white jadeite may have a high Ti content, its Fe content is low. UV–Vis spectra showed a broad absorption band at 610 nm associated with Fe2+-Ti4+ charge transfer and a gradually increasing absorption band starting at 480 nm related to V4+. Combining the chemical composition and the characteristics of the UV–Vis spectra, we infer that the blue coloration of jadeite is attributed to Fe2+-Ti4+ charge transfer; i.e., the presence of both Ti and Fe in blue jadeite plays a key role in its color formation. V4+ exhibited no significant linear correlation with the development of blue coloration. Prominent oscillatory zoning was observed in the jadeite, transitioning from NaAlSi2O6-dominant cores to Ca-Mg-Fe-Ti-enriched rims, reflecting the trend of fluid evolution during blue jadeite crystallization. Petrographic analysis indicated that the formation of the Myanmar blue jadeite occurred in two or three stages, with the blue regions forming earlier than the white regions. The blue jadeite also underwent significant recrystallization. Our findings contribute to the understanding of the formation of blue jadeite and the diversity of colors in jadeite jade.