Heavy Mineral Concentration on the Visakhapatnam - Konada Coast as Evidenced by Magnetic Susceptibi1ity and Radioactivity

Magnetic susceptibility, radioactivity, bulk density (ρ) and texture of black sands from the Visakhapatnam-Konada belt on the east coast of India were studied. The sands are fine-grained and well sorted with a nearly symmetrical distribution. Mass susceptibility (χ) and radioactivity (R.A.) are related to weight percentage of magnetic minerals and grain percentage of radioactive minerals respectively. The magnetic fraction is made up of magnetite and ilmenite. The radioactive minerals present in the sands are monazite and rarely zircon. Susceptibility and R.A. of finer sieve fractions are high, reflecting higher proportions of magnetic and radioactive minerals.

Mass susceptibility, Radioactivity and bulk density of black sands are high south of outcropping rock formations across the coast, reflecting heavy mineral concentration. A structural aspect of the coast, namely the Eastern Ghat formations cutting across the coast, seems to be one of the controls on heavy mineral concentration.