[Research of genesis of black bands in Burma jadeite]

A kind of jadeite jade with black bands appeared in the mining area of Burma, which presents a gray-black to black appearance. X-ray powder diffraction analysis shows that the components of the sample are mainly jadeite and a small amount of omphacite. A large number of small, dark mineral inclusions were observed by SEM (scanning electron microscopy), distributed in the mineral grain gaps and tensional fractures of jadeite. These inclusions show specific peak at 1582 cm(-1) , and some of them also show a peak at 1346 cm(-1), indicating that these black inclusions are single crystal graphite and amorphous graphite, based on characteristic Raman spectra. These graphite inclusions forming different types of group lead to great light scattering loss in the range of 3000 nm to visible wavelength resulting in large transparency loss and cause the black band in sample. Two series of zircons were found in the sample by microexamination with high crystallinity and inconspicuous metamictization, as testified by Raman spectroscopy.