Textural and Chemical Characters of Lean Grade Placer Monazite of Bramhagiri Coast, Odisha, India

Abstract

The present study aims to investigate the textural, mineralogical and geochemical characteristics of lean grade placer monazite from the Bramhagiri beach sand deposit to assess the possibility for its use in industrial applications. The bulk back dune sand deposit with 18 samples showed the elements uranium and thorium in traces, phosphorus and calcium in minor amounts, and alumina, silica and titanium in major amounts. Since apatite was absent in this placer deposit, P and Ca were attributed to monazite only. Based on the chemical analysis, it was established that the monazite mineral exists in this deposit. The monazite is generally below the −150- to +90-micron size range, and the concentration of the monazite mineral in the bulk back dune sand is around 0.01% by weight. The structural data and complete chemical analysis established that the monazite is Ce-monazite. The monazites with other heavy mineral sands of the Bramhagiri beach placer deposits were derived from the Eastern Ghats, which closely resembles the mineralogical composition of khondalite, charnockite, leptynite and pegmatite groups of rocks. The Eastern Ghats’ provenance appears to be the primary source for the heavy mineral assemblages of the Bramhagiri placer deposit. Thus, these monazite sands are derived from the granulite facies of metamorphic rocks such as khondalites and charnockites from the Eastern Ghats group of rocks. Garnet is the major mineral, following ilmenite and sillimanite. Zircon, rutile and monazite are minor minerals in the deposit. All these minerals are well liberated and have uniform shapes with variable densities and size ranges, with different magnetic, electrical and surface properties. Hence, the occurrences of these heavy minerals are of economic importance. Further, these minerals can be recovered individually for industrial applications.