Nepal Gem Tourmalines

Abstract

Gem quality tourmaline crystals from pockets in the pegmatites at Hyakule and Phakuwa in the Sankhuwa Sabha District, Kosi Zone, eastern Nepal, have been mined for over 50 years with a production of at least a ton of gem crystals. Mining continues, despite land-slide problems, in sporadic operations at both mines. Minerals associated with the elbaite tourmalines include quartz, muscovite biotite, lepidolite, beryl (occasionally of gem aquamarine), both spessartine and hessonite garnets, danburite, hambergite, apatite, and both micro-cline and cleavelandite feldspar The gem-bearing pegmatites are associated with schist and carbonate rocks in the Khitya Khola formation as defined by E. Andrews in an article in this journal in 1985. The origin of these intrusive pegmatites is still controversial as no body of source granite is exposed in the area. Additional tourmaline-bearing pegmatites are reported in the Sankhuwa Sabha, Taplejung Jajarkot, and Rasuwa districts. Five distinct mineral species of the tourmaline group occur in Nepal.