Some Characteristics of Nanyaseik Area Corundum and Other Assorted Gemstones in Myanmar

摘要

The rock sequence of the study area consists of medium to high grade metamorphic rocks, marble, gneiss and intrusive igneous rocks, mainly biotite microgranite and serpentinite. Although the primary occurrences of gemstones in this area seem to be scarce, the secondary placers gem-bearing deposits are noteworthy. The Nanya rubies are characterized by their distinct colours of which, the commonest colour being, light pinkish red and intense red and rarely pigeon's blood red. A glassy texture with excellent transparency makes the stone more attractive. In crystal forms, rubies usually have rounded corners, rhombohedrons, pinacoids and not well developed prism faces. Habitually, rhombohedral faces display coarse striations and some with pitted surfaces. It is probable that the Nanyaseik area is situated near the plate boundaries and within the northern splay of the Sagaing fault. Moreover, it also forms a segment of Jade Mine region. Therefore, it is reasonable that the pressure had played an important role more effectively than the temperature in the process of metamorphism.