Heavy Mineral Potentiality and Alteration Studies for Ilmenite in Astaranga Beach Sands, District Puri, Odisha, India

摘要

Fifteen beach sandsamples were collected from a depth of 1mt at different locations of the Astarangabeach, Puri with an interval of 300 mts. The beach sand samples were studiedfor heavy mineral concentration at different location points and were subjectedto scanning electron microscope studies for the mineral ilmenite. The percentageof total heavy mineral in Astaranga beach varies from 16.42% to 24.47%. Theimportant minerals are ilmenite, rutile, zircon, sillimanite, garnet, monazite,pyroxene and others. For all samples a set of sieves bearing ASTM nos. 30, 40, 60,80, 100, 120, 140, 170 and 200 corresponding to 0.59 mm, 0.42 mm, 0.25 mm,0.177 mm, 0.149 mm, 0.125 mm, 0.105 mm, 0.088 mm and 0.074 mm respectively wereused to separate different size fractions. The sieve mesh sizes vary from 0.59 mmto 0.74 mm. It was observed that maximum concentration of heavies was confinedto +200 ASTM sieve or 0.74 mm. The total average heavy mineral concentrationand light mineral concentration was found to be 20.07% and 79.49% respectively.The concentration percentage of different heavy minerals varied from higher tolower in the order like ilmenite, zircon, sillimanite, garnet, rutile,pyroxene, monazite and others. The ilmenite mineral in this area is found tohave altered to secondary phases like pseudorutile, leucoxene and rutile alongthe fractures, cavities and grain boundaries. The alteration condition was observedas streaks, irregular patches, bands, and rim like structures around theilmenite grains. Detailed study of alteration in ilmenite was carried out byEnergy Dispersive Spectrometer (EDS) attached to Scanning Electron Microscope.The potentialities of heavies found at different locations of the Astarangabeach suggested a good source for the exploration. The alteration of themineral ilmenite and high concentration of heavy minerals clearly pointed tothe sedimentary environment and mechanical concentration process due torepeated wave action.