Canada is one of the main producing areas of green nephrite, and there are three main mines in Canada: Polar, Cassiar and Kutcho; nevertheless, the qualities of green nephrite from different mines are different, but 1ittle research has been devoted to this diversity. In this paper, characteristics of mineral compositions and chemical components of green nephrite samples from Cassiar were studied by means of the conventional gemmological testing, orthogonal polarization microscope, electron microprobe analysis, X-ray powder diffraction and infrared spectrometer.The results indicate that the main mineral components of Cassiar green nephrite are tremolite and actinolite, together with minor quartz, whereas the black solid inclusions are iron-chromite and grossular, suggesting that the green nephrite from Cassiar of Canada is a product of the alteration of ultrabasic rocks. Its type is the same as that of the Manasi and the Hotan nephrite deposit. A comparison of the Cassiar mine with the Kutcho mine shows that the values of their main elements in green nephrite are different.