Abstract:

Na’e small pegmatitic beryllium deposit has recently been proved in the western Yunnan Province. The ore bodies are found in garnet and albitite granite pegmatite dikes within monzonitic granite. These ore bodies range from 100-1 150 m in length, 0.43-3.70 m in thickness ,and contain BeO, Ta2O5, Rb2O in concentrations of 0.007%-1.790%, 0.003 2%-0.053 3% and 0.041%-0.317%, respectively. The mainly major useful element in the ore is beryllium, associated with tantalum and rubidium. Some few ore mainly contains tantalum, and associated with beryllium and rubidium. The ore minerals include beryl, niobium tantalite, muscovite and K-feldspar. The beryl-bearing pegmatite is a siginificant prospecting indicator in the area, followed by garnet bearing albionite pegmatite. EPMA results show that beryl falls into the alkali-free beryl to low alkali beryl. The molecular formula for beryl is Be2.8928-2.9481Al1.9766-2.0225Si6O18. Muscovite contains w(Li2O) 0.500 1%-2.427 9% and w(Rb2O) 0.730 3%-2.304 2%, belonging to muscovite-polysilica muscovite-Li-rich muscovite. K-feldspar has a high w(Rb2O) content of 0.486 1%-1.033 4%, with a molecular formula of K0.8932-0.9713 \[Al1.0013-1.0151 Si2.9809-2.9990O8\]. Energy spectrum of garnet is characterized by the development of Mn and Fe bipeaks, mainly spessartine (Spe) and almandine (Alm), with spessartine accounting for 67.02%-69.07%, indicating a magmatic origin of spessartine. Beryllium is mainly occurred in beryl, rubidium in K-feldspar and muscovite, and lithium in muscovite-polysilica muscovite-Li-rich muscovite. The composition of muscovite and berylite shows that lithium was not initially enriched in granitic magmas in the Na’e  area, but the late pegmatite evolution involving highly enriched F-Li fluid activity in magmas played an important factor in the abnormal enrichment of rare metals in this area.

Key words: Na’e beryllium deposit in western Yunnan Province')">

Na’e beryllium deposit in western Yunnan Province, pegmatitic beryllium deposit, granite pegmatite, beryl, mica, K-feldspar, garnet, rare metal deposit