The Dharwar System

What is the Dharwar System, and how old is it really?

• The Dharwar System is India’s oldest metamorphosed rock system, built from ancient sedimentary and volcanic rock. It formed in the Archean era, over 2.5 billion years ago.
• It takes its name from Dharwad, the Karnataka town where geologists first studied these rocks.
• The system forms part of the Dharwar Craton, a stable, ancient block of continental crust. It also sits within the wider Peninsular Gneissic Complex.

Where does this rock system actually sit?

• Its main belt runs through the Dharwad, Shimoga, and Chitradurga districts of Karnataka.
• Geologists divide the craton into three blocks: Western, Central, and Eastern.
• Three rock groups make up the system, from oldest to youngest: Sargur, Bababudan, and Chitradurga. Sargur rocks survive only as scattered older enclaves inside the Western Block’s gneiss.

Which rock types carry the gold, and why are there no fossils?

• The system’s rocks include schists, quartzites, phyllites, slates, and crystalline limestones and dolomites.
• Gold sits mainly in schist belts, long narrow strips squeezed between older granite and gneiss. Many of these are greenstone belts, formed from ancient volcanic lava and ash.
• Some quartzite layers alternate with banded iron formations, iron-rich bands laid down when early oxygen-producing microbes reacted with dissolved iron in ancient seawater.
• The rocks hold no fossils at all. Billions of years of intense metamorphism destroyed any trace of ancient life, a genuine exam trap for students who assume “sedimentary” always means “fossil-bearing.”

How does the Dharwar System compare to India’s younger rock systems?

• The much younger Vindhyan System, by contrast, does preserve some early fossil-like structures.
• Rocks of similar Archean age also appear in Jharkhand, Chhattisgarh, Odisha, and parts of the Himalayas, but as separate outcrops, not one continuous belt.
• The Singhbhum Craton in Jharkhand yields iron ore, copper, and uranium. The Bastar Craton in Chhattisgarh holds iron ore reserves that feed nearby steel plants.

What minerals besides gold come from these rocks?

• The Dharwar System is a genuine mineral treasure house: gold, iron ore, manganese, copper, and chromite all occur within it.
• The Bababudan group hosts high-grade iron ore. Manganese and chromite from these rocks go into alloy-steel production.
• Dharwar-age granites are also quarried as building and monument stone.

What makes the Kolar Gold Fields so unusual?

• The Kolar Gold Fields sit in a narrow greenstone schist belt, and its Champion Reef mine is one of the deepest gold mines in the world, with shafts once running past 3 km underground.
• Kolar was among the first places in Asia to run on hydroelectric power, needed to run the pumps and lifts for such deep shafts.
• At its peak, Kolar supported an entire dedicated township, complete with hospitals, schools, and clubs.

What did India just approve for the Kolar Gold Fields?

India is reviving mining at the Kolar Gold Fields, its first gold-mine restart since independence, after Karnataka’s Cabinet approved the Centre’s proposal in June 2024. (Source: Trak.in, June 16, 2025)

• The project targets 13 old tailing dumps spread across roughly 1,003 acres, holding about 32 million tonnes of leftover material.
• Engineers estimate around 23 tonnes of gold remain recoverable, using surface-level extraction methods, not the old deep-shaft mining.
• The modern process, heap leaching combined with carbon-in-pulp recovery, targets about 750 kg of gold a year. The original mine closed in 2001.