TITLE:
Heavy Mineral Potentiality and Alteration Studies for Ilmenite in Astaranga Beach Sands, District Puri, Odisha, India
AUTHORS:
Sanuprava Mohapatra, P. Behera, S. K. Das
KEYWORDS:
Alteration, Astaranga, Heavy Minerals, Ilmenite, SEM, EDS
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.3 No.1,
March
25,
2015
ABSTRACT: Fifteen beach sand
samples were collected from a depth of 1mt at different locations of the Astaranga
beach, Puri with an interval of 300 mts. The beach sand samples were studied
for heavy mineral concentration at different location points and were subjected
to scanning electron microscope studies for the mineral ilmenite. The percentage
of total heavy mineral in Astaranga beach varies from 16.42% to 24.47%. The
important 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 were
used to separate different size fractions. The sieve mesh sizes vary from 0.59 mm
to 0.74 mm. It was observed that maximum concentration of heavies was confined
to +200 ASTM sieve or 0.74 mm. The total average heavy mineral concentration
and light mineral concentration was found to be 20.07% and 79.49% respectively.
The concentration percentage of different heavy minerals varied from higher to
lower in the order like ilmenite, zircon, sillimanite, garnet, rutile,
pyroxene, monazite and others. The ilmenite mineral in this area is found to
have altered to secondary phases like pseudorutile, leucoxene and rutile along
the fractures, cavities and grain boundaries. The alteration condition was observed
as streaks, irregular patches, bands, and rim like structures around the
ilmenite grains. Detailed study of alteration in ilmenite was carried out by
Energy Dispersive Spectrometer (EDS) attached to Scanning Electron Microscope.
The potentialities of heavies found at different locations of the Astaranga
beach suggested a good source for the exploration. The alteration of the
mineral ilmenite and high concentration of heavy minerals clearly pointed to
the sedimentary environment and mechanical concentration process due to
repeated wave action.