The coastal sands between Nizampatnam and Lankavanidibba near the estuary of the river Krishna contain as many as 20 heavy minerals of high commercial value. They include titanium, zirconium and rare earths. Researchers from Andhra University, Visakhapatnam and Yogi Vemana University, Kadapa, have found heavy minerals spread over an area of 1,825 square km along the estuary of the river Krishna. As many as 60 transects (locations) have been identified along the 24-km stretch between Nizampatnam and Lankavanidibba in Guntur. The research team comprised Dr K.S.N. Reddy, D. Deva Varma, E.N. Dhanamjaya Rao and B. Veeranarayana of Andhra University, and T. Lakshmi Prasad of Yogi Vemana University.
“The beach sands, deposited by the river Krishna, contain ilmenite and magnetite (47.67 per cent), pyriboles (20.35 per cent), garnets (3.66 per cent), epidote (3.23 per cent) and sillimanite, zircon, staurolite, kyanite, apatite, spinel, monazite, biotite, topaz, leucoxene and chlorite in less than three per cent concentration,” Dr K.S.N. Reddy said. Ilmenite is a titanium-iron oxide mineral, useful in the production of titanium oxide. Researchers divided the area into seven sectors for purpose of the study and found different concentration of heavy minerals in them. The sectors nearer to the river mouth showed higher concentration of high specific gravity minerals like ilmenite and magnetite than those away from the river mouth.
Sector I had the highest concentration of heavy mineral, which ranged from 12.47 to 31.42 per cent. The dominant heavy minerals were ilmenite (34.88 per cent), followed by sector II with heavy mineral concentration ranging from 12.73 to 29.75 per cent. It contained ilmenite, magnetite, pyriboles, besides gemstones like garnet. “Ilmenite, magnetite, pyroxenes, amphiboles, garnet, epidote and sillimanite are heavy mineral assemblage in the Nizampatnam- Lankavanidibba area. The wave processes are responsible for heavy mineral concentration and the redistribution of heavy minerals along the coast is due to alongshore currents and creek dynamics,” said Dr Reddy.