Directorate of Mines & Geology
Government of Goa

Mineral Resources of Goa - MANGANESE

  • The manganese deposits of Goa are of Lateritoid type. Geographically the manganese deposits are more concentrated in the southern parts of Goa
  • The manganese ore deposits of Goa occur as lensoid concordant bodies within the pink shales and phyllites and the associated quartzite’s.The deposits generally occur at the edge of a plateau or ridge from where the slope suddenly falls. Manganese deposits are also noticed on the small humps and elevations along the slope of hill and on some mounds and knolls. Very rarely or perhaps never does the manganese deposit occur at the top of a plateau or ridge. This characteristic topographic control for manganese ore concentration could be seen at all places. Many of the humps on the slope of the hills and small low mounds and knolls on which the manganese deposits occur forms minor anticlinal or domal structures. The concentration of ore is maximum at the core or apex and dwindles down on both the sides along the slopes. The lengths of the individual deposit vary from 20 m to 500 m and the widths from 15 m to 60m.
  • The depth of concentration into the hill varies from about 15 m to 60 m. When the quarry working is pushed gradually into the hill, the concentration of ore decreases and ultimately vanishes into the altered country rock.
  • The Goan manganese ores contains some iron, increasing as the manganese content decreases. Iron ores also contain a certain amount of manganese.
  • The Goan manganese ores are generally poor in grade with manganese content varying from 30 to 45%. But at places the grade increases to 58-60% manganese. There are some thin concentrations of 2 to 3 m thick zones of black iron and ferruginous manganese ore in some deposits above the manganese ore.
  • The concentration and enrichment of ores are maximum at and near the surface, dwindling down with depth. The big boulders and even a crude bedded nature of the ores at the upper zones give place to smaller boulders and nodules.