A Sedimentological Study of Manganese Powder from Devada, Srikakulam District, Andhra Pradesh

Though much work has been done on the manganese ore deposits of Koduru, Devada, Duvvam and Garividi, no attempt has been made so far to study the powder form occurring as thin beds Intercalated with the primary ore bands. Therefore, an attempt is made in the present paper to know the source of the manganese powder, its depositional environment, mineral constituents and textural features. For this purpose, the manganese powder from Devada was subjected to magnetic separation, and the magnetic and non-magnetic parts were analysed by size analysis, ore microscopic and X-ray studies.

The following are some of the Significant conclusions arrived at from this investigation (1) From the size analysis it is shown that the source of the manganese powder is very near and almost in situ, and the powder was formed due to crushing from the primary bedded ores. (2) The elongation and roundness studies show that most of the grams are not spherical, the average length is about 1.4 to 1.7 times the average width; and this also indicates a near source for the manganese powder. (3) The magnetic part consists of vredenburgite, magnetite and hematite with little pyrolusite, while the non-magnetic part comprises pyrolusite, psilomelane, hematite, hollandite, braunite, bixbyite, geothite and limonite. (4) A new mineral, quenselite (PbMnO₂(OH)) is reported for the first time from this area. (5) The magnetic susceptibility of different powder fractions is correlated with the amount of the sum of vredenburgite and magnetite; of these, coarse fractions contammg much vredenburglte are having high magnetic susceptibilies.