7 PRECIOUS STONES IN THE SOUTHERN COASTAL ZONE OF SRI LANKA Jinadasa Katupotha Abstract Sri Lanka has many varieties of precious (gemstones) and semiprecious stones globally known for more than 2500 years. The precious stones are mainly ruby, sapphire, emerald and chrysoberyl and the semiprecious stones consist of spinel, zircon, amethyst, aquamarine, garnet, moonstone, quartz, topaz and tourmaline. Macro and microscopic analysis show that semiprecious gemstones mainly consist of green and honey tourmaline, spinel, topaz and garnet. Minerals of corundum family are rare, while locally concentrated gold dust is also present. The presence of different varieties of gem minerals and gold dust in petrographic slides leads to the conclusion that mining has economic value in localised areas. Traditional manual mining methods are suitable to obtain gems from the deposition sequences. Although the gem bearing gravels are not so deep (less than 3.0m), fluvial and wind-blown deposits overlay them. Quartz and ironstone gravel of the gem- bearing layers has been deposited as fluvial material under a dry climatic condition during the last glacial period. INTRODUCTION Sri Lanka has been famous for more than 2500 years for its gemstones owing the fact that in an area of only 65,610 km 2 , many varieties of precious and semi-precious stones exist. However, until recently, exploration for gemstone was carried out using traditional methods only. Traditional gem mining areas are concentrated mainly in the Ratnapura, Openayake, Balangoda, Deniyaya and Rakwana areas, and the methods of gems exploration are still based on information passed down by word of mouth (Dissanayake et. al, 1993). Extensive gem bearing gravels are found in the coastal area between Ranna and Pallemalala in the Hambantota District. They are of considerable geological significance in the study of stratigraphy, geoarchaelogy and sea level changes. Minerals of the corundum family, mainly ruby, sapphire as well as Cat's Eye (gem quality variety of the chrysoberyl) found in these gem fields. Proceed. Ann. Res. PGS (2001) Faculty of Graduate Studies. Proceedings of the Annual Research Session. PGS (2001). University of Sri Jayewardeneputa, Nugegoda, Sri Lanka.