Gem mineral distribution in the area around Uggalkaltota off Balangoda

Abstract

The area around Uggalkaltota off Balangoda lies in the Precambrian Metamorphic terrain of Sri Lanka. Geological and detailed structural mapping show that the area is adjacent to a major geological boundary. Among the major types of rocks found in the area marble rocks show effects of alterations and injections as calcite veins into surrounding rocks. The area is rich in large pegmatite dykes and quartz veins. A Stream Sediment Survey carried out in the area shows high concentrations of gem minerals in association with marble rocks and pegmatite dykes. Mineralogical analysis of soils and rocks show that pegmatite dykes contain considerable amounts of topaz and no other gem minerals except moonstones. Carbonate rocks in the area contains variety of gem stones (including topaz). Furthermore concentrated pockets of gem stones are found in the carbonate rocks in the area.