Geological and Composition Features of Nephrite from Qinghai Province

Nephrite from Qinghai Province has been recognized and loved gradually by people since the early 1990s.Especially，since it was selected to make the Gold，Silver，Bronze medals of 2008 Beijing Olympic Games，people have a great interest in it.At present，the nephrite from Qinghai Province has been a major source of nephrite in China.The geological features of nephrite from Qinghai Province are introduced in this paper.The nephrite samples of various colours and different causes from Qinghai Province are comprehensively and systematically tested by using the methods of polarizing microscopy，X－ray fluorescence spectrometer，infrared spectrometer，X－ray powder diffraction spectrometer and so on.The results show that the composition features of nephrite from Qinghai Province is SiO₂，MgO and CaO as the main chemical ingredients and its contents are stable.The main mineral composition of nephrite from Qinghai Province is tremolite and its content is more than 99%.