Mineralogy and coloration of oil-green jadeite jade were investigated using X-Ray diffraction (XRD), Fourier transform infrared absorption spectroscopy (FTIR) and scanning electron microscopy (SEM). XRD results show that “flesh” of oil-green jadeite jade is mainly composed of relatively pure jadeite, whereas the “skin” of which is dominated by jadeite, chlorite and chrysotile. The mineral constituents revealed by FTIR are fairly consistent with XRD. Three typical adsorption peaks of ~2 956, ~2 919 and ~2 850 cm-1 related to organic matters occurred in both “flesh” and “skin” of oil-green jadeite jade. Jadeite in “flesh” exhibits an obvious columnar growth and has a better crystallinity than that of “skin”. However, jadeite in “skin” is richer in magnesium than that of “flesh”, suggesting an intense water-rock reaction of jadeite in “skin”. Chrysotile just occurs in “skin” of oil-green jadeite jade, and it presents a curved crystal plane. Flaky chlorite was detected in both cracks of “flesh” and “skin”, which might be the main cause of coloration of oil-green jadeite jade. Chlorite, formed in the reducing water-rock reaction, would adsorb or wrap a certain amount of organic matters, resulting in the occurrence of the characteristic adsorptions of oil-green jadeite jade.