Abstract:

The alaskites/pegmatites from the Spruce Pine region of USA and the muscovite granites/pegmatites from the Altay region of Xinjiang, China, were comparatively studied. The pegmatites from both regions might be melt-vapor differentiation products of the peraluminous granitic magmas. The pegmatites from the Spruce Pine region with high-purity quartz were developed on the schist or gneiss background, whose major rock-forming minerals are rich in plagioclase, showing high Na/K ratios, high large-ion lithophile elements Sr and Ba contents, low high-field strength and rare earth elements contents, positive Eu anomalies，and low impurity elements contents in quartz. All these characteristics can be used as the discrimination criteria of high-purity quartz pegmatities. The Altay region of Xinjiang is abundant of pegmatites, and some samples studied showed the features which evidenced that the Altay pegmatite region has a perspective to find the gualified pegmatites with high-purity quartz.

Key words: pegmatite, high-purtity quartz, Spruce Pine, Altay