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An ancient greenstone belt that hosted one of the deepest mines humans have ever dug in pursuit of gold.

Kolar sits on a greenstone belt of the Dharwar Craton — a band of Neoarchean volcanic and sedimentary rocks, roughly 2.7 billion years old, that were folded and metamorphosed deep in Earth’s early history. Threaded through these ancient rocks are the gold-bearing quartz veins that made the region famous.

Mining at Kolar reached extraordinary depths — several kilometres below the surface — making it for a long time one of the deepest mines in the world. The mines have since closed, but the belt remains a classic example of Archean gold geology.

Sources

• Geological Survey of India

A short reference note: this summary draws on third-party sources such as the Geological Survey of India and Wikipedia. In time I plan to give every geological feature its own learning-oriented write-up — with custom diagrams, graphs, and study pointers — as I’ve already done for the 11 locations that have an Instagram reel.