According to a Geological Survey of India (GSI) assessment, Meghalaya and Nagaland contain substantial amounts of coal, limestone, and minor strategic metals, while Assam and Arunachal Pradesh have shown promise as areas for graphite, vanadium, REEs, base metals, gold, coal, and limestone.
The 17 chemically related elements known as rare earth elements (REEs), which include lanthanum, neodymium, and yttrium, are essential for use in electronics, magnets, and green technology. Divided into light and heavy categories, REEs are essential components of electric vehicles, wind turbines, modern electronics, and defense systems.
The Lodoso region in the Papum Pare district of Arunachal Pradesh has produced a defined resource of 2.15 million tonnes of ferruginous phyllite that contains rare earth elements (REEs), with an average grade of 1.08 percent total REE (including yttrium). Significant levels of neodymium (Nd) have also been found in the districts of East Kameng and West Siang. Trench sampling and pedo-geochemical investigations have shown promising results for the Jashora and Samchampi alkaline complexes in Assam. Together with related elements like Nb and Y, these complexes have yielded REE values between 1000 and 5000 ppm.
Rare metals (RM) and rare earth elements (REE) may also be found in the granite gneisses of the Assam Meghalaya Gneissic Complex (AMGC). Titaniferous bauxite cappings are found in the Sung Valley ultramafic-alkaline-carbonatite complex in Meghalaya.
The granitic and gneissic cores of the Mikir Hills, the Shillong Group rocks in central Assam, and the sedimentary sequences of the Brahmaputra and Barak plains dominate the state's geology. The State has historically been recognized for its natural gas and oil reserves, but it also has rich amounts of REEs, glass sand, iron ore, and limestone. With more than 1,490 million tonnes identified from the Dima Hasao district alone, limestone is Assam's greatest non-energy mineral resource. These materials are appropriate for cement and other industrial uses and are found in the Jaintia Group's tertiary formations.
According to reports, the Chandardinga area in the Dhubri district contains iron ore deposits with an estimated resource of 18.29 million tonnes at an average grade of 37.45% Fe. Placer gold has been found in the Subansiri River basin in upper Assam, while glass sand with a high silica concentration has been found in the districts of Nagaon and Karbi Anglong. According to the research, these gold discoveries, despite their modest grade, are significant markers of possible upstream mineralization. The lush plains of Assam and Tripura are formed by Quaternary sediments that are widely distributed in the basins of the Brahmaputra and Barak rivers.
Recent research has shown promise for placer gold and groundwater-hosted lithium, even though these regions are typically less promising for hard-rock minerals, it continued. Through Geological Reports (GRs) and Geological Memorandums (GMs), GSI has conducted over 200 mineral exploration projects and identified 38 prospective blocks in the region across several states, including Arunachal Pradesh, Assam, Meghalaya, and Nagaland, between 2015 and 2024.