Delineation of potential sites for gemstone mining in Kura Ganga catchment, Ratnapura: a GIS approach

Abstract

Sri Lanka has been known as 'Ratnadeepa', which translates to 'Island of gems' because of the precious natural gemstones found in its gravelly soil. Even though the gem industry in Sri Lanka extends back to ancient times, studies on patterns of gemstone occurrences were rare. However, identification of potential gem bearing lands can provide guidelines in mining and land valuation. This study was carried out to identify the potential lands for gemstone mining in Kuru Ganga catchment, Ratnapura, based on patterns of gemstone occurrences and mining cost using integrated geo-spatial technologies. Fieldwork was conducted to collect gravel samples from riverbanks and gem mines. The samples were subjected to microscopic analysis to trace potential gemstones. The results obtained were combined with the data gathered from gem mines and mapped on a GIS platform to identify the occurrence patterns. Mining cost at each sampling location was estimated based on depth to the gem bearing gravel layer, "illamaSubsequently, potential lands for feasible gemstone mining were delineated through a knowledgedriven weighted analysis. The results depict that the South Western region of the Kuru Ganga catchment encompasses the highest feasibility of gem mining while North Eastern region of the catchment has the least feasibility of gemstone mining based on mining cost and values of potential gem varieties in the area.