Nandkumar M. Kamat
This article follows last week’s focus on rare earth elements and yttrium in Goa, because suddenly, we see that some news is flashed that this or that non-ferrous element or deposit is ‘discovered for the first time’ in Goa. So, it is important to present what has already been surveyed and published officially about the elements in the periodic table found in Goa.
This article is about nickel, chromium, and cobalt in Goa. These three metals form the triad of metals that quietly sustain modern civilisation. Nickel is essential for stainless steel and battery cathodes; chromium strengthens alloys and resists corrosion; cobalt stabilises superalloys and stores power in rechargeable batteries. These three elements underpin electric mobility, renewable energy systems, and high-temperature industrial processes.
As India invests heavily in deep-sea exploration of polymetallic nodules in the Central Indian Ocean Basin to secure its future supply of critical metals, it is important to recognise that measurable concentrations of the same elements already exist within the country’s landmass. The Geological Survey of India has, over the last 15 years, produced detailed geochemical data showing that parts of Goa contain discernible enrichments of nickel, chromium, and cobalt in lateritic and ultramafic terrains. This knowledge provides a valuable terrestrial baseline and invites renewed attention to India’s accessible onshore resources, even as the nation explores mineral wealth several kilometres beneath the ocean surface.
Three GSI investigations conducted between 2006 and 2019 mapped the entire state under the National Geochemical Mapping Programme using X-ray fluorescence and inductively coupled plasma mass spectrometry. The surveys covered the coastal belt, inland ferruginous tracts and the eastern highlands extending through Usgaon, Dharbandora, Molem, Karmani, Takwada, and Makazan. They consistently revealed that nickel, chromium, and cobalt occur together within the ultramafic and banded iron formation belts of eastern and south-eastern Goa.
Nickel is most abundant in the lateritised ultramafic complexes of the Usgaon–Dharbandora–Molem–Karmani–Takwada sector, with concentrations ranging from about 80 to 180 parts per million. The metal occurs in soils and slope-wash sediments derived from serpentinised peridotite and gabbro, fixed within ferruginous laterite rich in iron and manganese oxides. Stream sediments from the same area show comparable values, confirming that nickel remains residually trapped within the weathered profile. Moderate levels of 30 to 70 ppm extend westward to Sanvordem and Sanguem, while the coastal plains contain only background values below 20 ppm. The 2018–19 mapping phase traced the nickel anomalies as a northwest–southeast belt parallel to the Dharwar schist contacts near Makazan
and Takwada.
Cobalt closely follows this pattern. Concentrations vary between 40 and 137 ppm, peaking near Karmani and Takwada where cobalt is retained in lateritic crusts rich in iron and manganese. The earlier surveys of 2006–09 and 2017–18 showed the same positive correlation between cobalt, nickel, and chromium, indicating derivation from ultramafic protoliths. Values diminish westward through Dharbandora and Usgaon to below 20 ppm in the plains and coastal belt. Cobalt is present in regolith and slope deposits alike, showing that it remains immobile and stable under oxidising tropical conditions.
Chromium defines the core geochemical axis of Goa’s eastern uplands. Maximum concentrations of about 2700 ppm occur in banded iron formations and quartz-chlorite schists east of Molem and Makazan. The Dharbandora–Usgaon corridor records 1500–2000 ppm, while the Karmani–Takwada zone averages 800–1000 ppm. Chromium occurs mainly as disseminated chromite within dunite and peridotite that have been altered to ferruginous laterite. In the inland plains chromium ranges between 200 and 400 ppm and drops below 100 ppm in the coastal and estuarine tracts. Stream sediments from the upper catchments of the Ragado and Cudnem rivers exhibit the same chromium enrichment, linking them directly to the ultramafic rocks of the
Dharwar belt.
Taken together, these three surveys show a stable spatial pattern. The eastern uplands from Usgaon to Takwada form a continuous enrichment belt containing nickel 80–180 ppm, cobalt 40–137 ppm, and chromium up to 2700 ppm. The central interior around Sanvordem and Sanguem displays intermediate levels, while the western lateritic plains and coastal areas register only background traces. The alignment of the anomalies follows the structural grain of the Dharwar schist belt and coincides with the ultramafic–banded iron formation contacts. All three metals occur with iron, manganese, and magnesium oxides that act as geochemical hosts.
The earliest 2006–09 survey first detected this Ni–Co–Cr triad in north-eastern Goa near Bicholim and Sattari, where small ultramafic lenses are interbedded with metamorphic schists. The 2017–18 study extended the mapping southward into Usgaon and Dharbandora and identified stronger anomalies.
The 2018–19 phase confirmed the continuation of this pattern through Molem, Makazan, Karmani and Takwada, recording the highest values. The combined dataset delineates a single geochemical corridor running northwest–southeast through the eastern highlands that defines Goa’s ultramafic province. Within this zone, nickel and cobalt are concentrated in the ferruginous oxide horizon of mature laterite, whereas chromium remains locked within
relict chromite grains deeper in the profile. The degree of lateritisation influences their relative concentration: thicker, more deeply weathered profiles show higher values, while thinner crusts yield lower ones. The coastal and
estuarine sediments derived from reworked lateritic material display negligible enrichment, confirming that the higher concentrations inland arise directly from the bedrock composition. Across the entire dataset the eastern belt averages about 2000 ppm chromium, 120 ppm nickel and 90 ppm cobalt. The inland plains contain half these amounts, and the coastal belt rarely exceeds 10–20 ppm for nickel and cobalt or 100 ppm for chromium. These figures have remained consistent across three surveys conducted over more than a decade, demonstrating the reliability of the
geochemical pattern.
When these land-based concentrations are compared with India’s officially documented data for polymetallic nodules in the Central Indian Ocean Basin, an instructive contrast emerges. The oceanic nodules, collected from depths of 4,500–6,000 metres, contain about 1.0–1.3 % nickel (10,000–13,000 ppm), 0.15–0.25 % cobalt (1,500–2,500 ppm), and roughly 0.01 % chromium (around 100 ppm). Thus, while nodules are far richer in
nickel and cobalt, Goa’s chromium content is significantly higher. The deep-sea nodules occur in remote abyssal plains under several kilometres of water, where retrieval requires highly specialised submersible mining systems, complex logistics, and compliance with international seabed regulations.
The cost, energy requirement, and ecological risks of such operations remain extremely high, making commercial recovery a long-term challenge. In contrast, Goa’s lateritic and ultramafic terrains, though containing lower concentrations, are accessible, well-mapped, and scientifically characterised. The metals occur in surface and near-surface horizons, within
land areas that are already part of established geological frameworks. As extraction and beneficiation technologies advance, these terrestrial sources may become more practical and sustainable to utilise than the technically demanding
deep-sea alternatives.
The geochemical evidence from Goa, obtained entirely from verifiable GSI data, therefore defines an inland belt rich in nickel, cobalt, and chromium relative to the rest of
the state. The concentrations—nickel up to 180 ppm, cobalt up to 137 ppm and chromium up to 2700 ppm—represent natural enrichments within weathered ultramafic and banded iron formations. The same metals sought today on the seabed are already present, in measurable form, within Goa’s ancient rocks
and laterites.
As India continues its search for strategic metals, this factual record of onshore occurrences stands as a reminder that critical resources may lie closer to the surface
than the ocean floor.
