[Vibrational spectra of black species of hetian nephrite (tremolite jade) and its color genesis].
ABSTRACT Black nephrite is a very uncommon jade type currently found only at Karakashi. In order to study the spectral characteristics and color-genetic mechanism of the black nephrite, samples collected from Karakashi were studied using EMPA, IR, Raman and XRD. The results are as follows: nephrite with different color has nearly the same major chemical compostions, while the black ones contain higher carbon; nephrite with different color has similar vibration spectrum, while the black ones show characteristic peak of graphite. It is speculated that the color of black nephrite is not only related with actinolite, but also related with the graphite inclusions. Obviously, Raman spectra is a very important nondestructive method to identify the color genesis and the origin of the black nephrite.