SRINAGAR: Altered volcanic rocks are the most probable source of lithium in the bauxite deposits of Salal-Haimna in Reasi, with the mineral subsequently released through weathering and concentrated in clay minerals, particularly kaolinite, a new Geological Survey of India study has found. The research establishes the geological mechanism behind Jammu and Kashmir’s first reported sedimentary-type lithium-bearing bauxite occurrence and identifies the clay-rich matrix, rather than the visible pisolites, as the principal host of the lithium.
The findings are reported in a research paper, Metallogenic environment for lithium mineralisation in bauxite from Salal-Haimna area, Reasi, North West Himalaya of Jammu-Kashmir, India, published in Discover Geoscience in 2025. The paper says the Salal-Haimna area hosts the country’s first reported occurrence of sedimentary-type lithium-bearing bauxite, belonging to the Cretaceous-Eocene period.
The paper was authored by Rohit Sharma, Shabir Ahmad Mir, PS Misra, Ajay Kumar and Deepak Kumar, all associated with the Geological Survey of India. Sharma and Misra are with GSI, Jammu; Mir is with GSI, Srinagar; Kumar is with GSI, Nagpur; and Deepak Kumar is with GSI, Jaipur. Rohit Sharma is the corresponding author.
The fall 2025 paper is published by Springer Nature owned Journal.
The Only Lithium Deposit
Lithium is regarded as a critical mineral because of its importance in batteries, electric vehicles, electronics and a range of industrial applications. The researchers note that India’s known lithium occurrences are predominantly hard-rock deposits associated with granite and granite-pegmatite, particularly in the Peninsular region.
Salal-Haimna is different. It represents the only known sedimentary-type lithium occurrence in India in which lithium is hosted in bauxite. The deposit is of the clay type, broadly comparable with lithium-bearing sedimentary deposits documented in parts of south-west China.
The deposit occurs within the Outer Himalayan sequence in Reasi district. The bauxite-bearing Jangalgali Formation, dating to the Cretaceous-Eocene, overlies the Proterozoic Sirban Limestone, with the contact marked by chert-quartzite breccia. The Jangalgali Formation is itself overlain by the Eocene Subathu Formation.
The Numbers
Earlier Geological Survey of India exploration had established lithium concentrations ranging from 15 to 2,847 parts per million (ppm) in bedrock samples and from 209 to 1,620 ppm in drill-core samples, with an average concentration of 583 ppm.
The present study provides a more detailed explanation of where that lithium resides within the bauxite. Chemical analysis showed that the clay-rich matrix contains an average of 503 ppm lithium, compared with 325 ppm in the pisolites. This indicates that the clayey matrix is the principal host of lithium mineralisation.
The more detailed LA-ICP-MS analysis produced substantially higher lithium readings in individual kaolinite-rich portions. In one mapped area, kaolinite showed lithium concentrations ranging from 1,274.92 to 8,333.73 ppm, while another clay mineral sample recorded 9,007.28 ppm. By comparison, lithium in pisolitic material was considerably lower.
The significance of these measurements is that lithium is not distributed uniformly through the bauxite. It is preferentially associated with clay minerals, with kaolinite emerging from the study as the dominant lithium-bearing phase.
Volcanic Rocks
The major contribution of the study is its explanation of how the lithium reached the bauxite.
During geological fieldwork, the researchers identified a previously important feature around Salal village: a greyish-white to creamish-yellow, fine-grained rock identified as tuffite. It occurs interbedded with quartzite and chert breccia and is overlain by the bauxite-bearing Jangalgali Formation.
Microscopic and scanning-electron studies revealed features characteristic of volcanic material. These included glass shards, vitric fragments and so-called Pele’s hair within the tuffite and claystone. The researchers also identified volcanic textures in associated rocks, including quartz phenocrysts and a glassy matrix.
Taken together, the evidence led the researchers to interpret the tuffite and associated claystone as volcanogenic material that had subsequently undergone alteration and devitrification, producing clay minerals.
The study therefore proposes that the volcanic material supplied the lithium. Weathering and leaching released lithium from the volcanic precursors, after which it was transported and adsorbed by clay minerals within the developing bauxite profile.
The authors specifically link the process to volcanic ash and rhyolitic material. In their proposed model, lithium was leached from volcanic rocks by meteoric and hydrothermal fluids and subsequently bound to clay minerals formed in ash-rich sedimentary environments.
The Key Host
The study’s mineralogical and geochemical evidence points repeatedly to kaolinite.
The bauxite is predominantly composed of diaspore, boehmite and clay minerals, while the claystone at its base is dominated by kaolinite and illite. LA-ICP-MS and SEM-EDX analyses showed that lithium is much more strongly associated with the kaolinitic matrix than with the aluminium-rich pisolites.
The researchers attribute this to kaolinite’s capacity to adsorb and retain lithium. Lithium released during weathering was therefore not simply lost from the geological system; it became concentrated in the clay-rich portions of the bauxite.
The process is described by the authors as involving eluviation, the removal and movement of soluble material through the weathering profile, followed by secondary concentration through adsorption onto clay minerals.
Complex History
The Salal-Haimna deposit developed through a sequence of weathering, sedimentation, alteration and later geological processes.
The researchers describe the bauxite as a diasporic profile, with a pisolitic upper horizon, a non-pisolitic or weakly pisolitic lower horizon and claystone at the base. The bauxite column generally ranges from 2 to 5 metres in thickness, with an average exposed thickness of about 3.5 metres.
The researchers argue that weathering of parent rocks released lithium, while clay minerals formed during the process acted as its principal repository. Subsequent diagenetic processes further altered the mineral assemblage.
They also point to the geological environment in which the deposit developed. The area represents a marine-continental transitional setting in which tropical climatic conditions, low salinity, paleohydrology and paleoclimate were favourable to the formation and enrichment of sedimentary bauxite-associated lithium deposits.
The Study
The researchers conclude that Salal-Haimna hosts clay-type lithium mineralisation within bauxite and that the underlying volcaniclastic rocks are the most probable source of the lithium.
Their evidence shows that the lithium is concentrated principally in kaolinite and, to a lesser extent, illite. The enrichment occurred through leaching of volcanic ash and subsequent adsorption by clay minerals within the bauxite profile. The authors consequently propose a genetic connection between the lithium-rich bauxite and contemporaneous volcanic activity.
The finding is important because it shifts the understanding of the Salal-Haimna occurrence from simply being a lithium-bearing bauxite deposit to a deposit with an identifiable metallogenic history: volcanic material supplied the lithium, weathering mobilised it, and clay minerals subsequently concentrated it.
Implications
The study provides a geological model that could be useful for further exploration of lithium-bearing lateritic and sedimentary deposits. Rather than looking only for visibly lithium-rich bauxite, the findings suggest that exploration should also examine the nature and distribution of associated volcanic and volcaniclastic rocks and the clay-mineral assemblages within the weathering profile.
The authors’ conclusion that the volcaniclastic unit beneath and around the bauxite represents the probable lithium source provides a geological target for understanding the wider mineralisation system. The identification of kaolinite as the principal lithium host also provides an important mineralogical guide for future investigation.
The research was undertaken as part of the approved annual field programme of the Geological Survey of India, Government of India, with no additional funding. The authors acknowledged scientific personnel at GSI laboratories in Lucknow, Bengaluru, Faridabad and Jaipur for assistance with the analytical work.
