Petrological and Mineralogical Characteristics of Qinghai Nephrite

The mineral phases of Qinghai nephrite are analyzed through the microhardness test, scanning electron microscopic observation, qualitative analysis by X-ray powder diffractometry and crystallinity analysis. Compared with the Xinjiang Hetian nephrite, some characteristics of Qinghai nephrite, such as higher hardness, higher crystallinity, lower content of tremolite, were found. The Qinghai nephrite mainly appears as the felt-like texture, the micro-fibrous texture and the micro-leaf-like texture with excellent orientability. Qinghai nephrite also presents the distinct deposit geological characteristics, such as lack of Mg and Si but abundant of Ca in its parent deposit rocks, weaker dynamic reconstruction but higher mineralizing temperature. It is believed to be the ultimate cause for differences in petrological and mineralogical characteristics of Qinghai nephrite from that of Xinjiang nephrite. And it is also one of the reasons why Qinghai nephrite always shows higher transparency and lower oil luster.