Use of Crystal Morphologies to Unravel the Origin of Vein Graphite in Sri Lanka

Abstract

Sri Lanka is well known for high quality vein graphite with extensive mineralization and large reserves. Many scientists have provided their tremendous efforts to discuss the origin of Sri Lankan vein graphite, but still it is controversial. However, recent investigations have proved that Sri Lankan vein graphite has a distinctly different structural variation. Nevertheless the relationship between the structural variations and the formation of vein graphite has not been studied yet. Therefore, this study focuses on the formation of Sri Lankan vein graphite, combining with the hydrothermal activities, crystallization process and crystal morphologies. Two major veins expose at the deeper levels and shallow levels, at the Kahatagaha – Kolongaha mine were selected for this study. SEM, XRD and purity analysis (ASTM – 561) have evidenced that, temperature, pressure gradient and influence of the impurity elements movement caused for the crystallization of different morphological layers with different purity, chemistry and crystallinity in a single vein.