Heavy minerals have become an essential commodity in modern-day technology. The objective of this study is to examine the current status of the heavy mineral industry of Sri Lanka. The present study also examines the economic viability of potential heavy mineral placer deposits, based on geochemical data. Field investigations suggested the occurrence of heavy minerals as beach-placers, and inland/raised beach deposits along the coastline of Sri Lanka. Geochemical results showed the enrichment of TiO 2 , Fe 2 O 3 , Al 2 O 3 , and trace elements, and depletion of other major oxides such as Na 2 O, K 2 O, MnO, MgO, CaO, and P 2 O 5 . Consequently, it suggests the abundance of ilmenite, leucoxene, rutile, sillimanite, garnet, and rare earth element (REE)-bearing heavy minerals in potential placer deposits. In contrast, this study illustrates the exported quantity (in the weight ratio of 35:3:1) of ilmenite, rutile, and zircon minerals during the last decade. Ilmenite is the dominant heavy mineral in Sri Lanka, and thus, its production and price volatilisations are essential to understand the current status and predict the future behaviour of the heavy mineral industry. Statistical observations suggest that the global production and unit price variations of ilmenite have increased gradually from 1950 to 2015. Besides, the forecasted variations in annual global production and unit price changes of ilmenite indicate healthy compound annual growth rates of 1.27% and 1.43%, respectively. However, Sri Lanka has less contribution (< 1%) to global ilmenite production. Consequently, the value addition of ilmenite must be highly encouraged with at least an immediate stage (e.g. synthetic rutile). The present study also highlights possible value addition stages of available heavy mineral resources (low-, intermediate-, or high-level value addition), and discusses action plans to improve the quality of the heavy mineral industry of Sri Lanka. In recommendations, imposing sustainable regulations and policies would uplift the heavy mineral industry of Sri Lanka. For example, value addition to local heavy minerals and terminating raw commodity export are highly recommended.

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Two radioactive mineral specimens (with compositions Th02 2.9--4.6 wt% and U02 5.8-7.8 wt%, respectively), collected from a placer deposit near Kolonna and a quarry near Masimbula, Sri Lank.a, were identified as metamict fergusonite. Identification was based on samples' chemical compositions and the observation that both specimens were transformed to crystalline fergusonite upon dry annealing at 550-600 °C, including the spectr oscopic observation of a high-temperature a� f3 transition (�750 °C) that is characteristic of this mineral. Strong negative Eu anomalies in chondrite-normalised REE patterns indicate reducing formation conditions. Both samples have experienced (perhaps even multiple) chemical alteration processes that led to the formation of decidedly heterogeneous internal textures. Fluid-driven alteration, especially along fractures and domain boundaries, has resulted in vast chemical changes.

Radioactive emanations (gamma-ray) from minerals due to the natural decay of radioactive elements (U, Th, K, etc.), is used as a tool to identify radioactive mineral occurrences. Sri Lanka is famed for occurrences of thorium-bearing minerals. A car-borne gamma-ray spectrometric survey has been initiated by Geological Survey and Mines Bureau (GSMB) to trace promising Th, U mineralization of the country. Herein we report and interpret the radiological, mineralogical, geochemical characteristics, and the possible origin of the radioactive anomalies identified during the survey in southwestern part of Sri Lanka covered by the Aluthgama-Galle geological sheet area. The typical gamma dose rate (GDR) recorded for the study area is 50 -80 nSv/h and the GDR values vary with the local geology. The identified anomalies were categorized into three groups based on the GDR and associated geology as; Group I: 100 -300 nSv/h, Group II: 300 -600 nSv/h, and Group III: > 600 nSv/h (Inland and beach/raised beach locations). The highest GDR value of 2300 nSv/h (Th -432 nSv/h, U -141 nSv/h, and K -49 nSv/h) is recorded at Uragasmanhandiya. Inland radioactive anomalies of Group III are associated with pegmatite occurrences (e.g. Uragasmanhandiya, Pituwala, Makubura, etc.) with characteristic mineralogy of quartz + feldspar + monazite + zircon ± biotite ± garnet ± ilmenite while higher monazite and zircon contents have been reported for beach/raised beach anomalies. The average Th/U ratio for the Group III anomalies is 32.99, which is higher than the average ratio for the upper crust, indicating the high abundance of Th compared to U in the terrain. Higher enrichment factors compared to the average upper crust have been reported for high field strength elements especially for Th, La, Ce and Zr (e.g. 28 -1400 for Th, 5 -407 for La, 5 -445 for Ce and 1 -291 for Zr). The combined analysis of radiology, mineralogy, and geochemistry shows that the radioactive anomalies mainly depend on the monazite content at each locality, and monazite serve as the main source for the high concentration of Th, La and Ce. The frequent distribution of radioactive anomalies and occurrences of pegmatites along the shear zones, faults and major lineaments of the terrain suggests a structurally influenced radioactive mineralization. The results of the analysis show that the main source for the monazite placer deposits in the southwestern coastal region is the monazite-rich granitic pegmatites and associated gneisses of the region. A widespread study is suggested to evaluate the U, Th, La and Ce mineralization in the country in terms of the extent and economic potential.