Xinjiang,is one of the most important granitic pegmatite output areas in the world.Many researchers focused on its formation time.In the past twenty years,a number of age data have been published,but their accuracy is questionable.So the conventional dating methods encounter problems in the pegmatite dating.In this paper,we analyze the age data of the No.3 vein in Keketuohai dated by a variety dating methods.The K-Ar,40Ar-39Ar and Rb-Sr isochron methods may not be suitable for pegmatite,because of hydrother...