Mineralogical characteristics of intrusive rocks in Boziguoer east mining area, Baicheng County, Xinjiang

The Boziguoer intrusive rocks in Baicheng County of Xinjiang are ore-bearing rocks with abundant useful elements such as Nb, Ta, U, Th, rare earth, Zr, Rb, Cs and Li etc.. A polarized light microscope and electron probe micro analysis (EPMA) is involved in detailed investigations into the mineralogical characteristics of intrusive rocks in this study. The results show that the main rock forming minerals include quartz, albite, potash feldspar, arfvedsonite characterized by rich Fe2+, Li-siderophyllite characterized by rich Si, Fe, low Al and poor Mg, and lepidolite characterized by rich Si, Li, low Al. Li-siderophyllite and lepidolite are minerals of trioctahedral mica group, belonging to the biotite-lepidolite series as different members. Moreover, the accessory minerals include pyrochlore, astrophyllite, fluocerite, monazite, thorite, fluorite, zircon, niobite etc. Then, the intrusive rocks are named as biotite alkaline granite. It is inferred that the magma might have been formed in an anorogenic intraplate tectonic setting in which diagenesis generally shows such characteristics as high-temperature, anhydrous nature and low oxygen fugacity.