The Kolar Gold Fields, in Kolar District of Karnataka in southern India, were until their closure in 2001 the principal gold-mining district of India and one of the deepest underground mines in the world. Mining at Kolar predates written historical record, with archaeological evidence of pre-classical Indian gold extraction, and continued under successive Indian dynasties through the colonial period and into independent India. The deposits gave India a substantial proportion of its domestic gold supply for several centuries, and the district was the principal training ground for the Indian deep-mining engineering profession.

Geological setting

The Kolar deposits are hosted in the Kolar Schist Belt, an Archaean greenstone belt of the Dharwar Craton, dated to approximately 2.7 billion years and one of the oldest gold-mineralised terranes in the world. Gold occurs in quartz-carbonate veins within metamorphosed mafic to ultramafic rocks, with mineralisation associated with the Champion Reef and Mysore North Reef structures. The principal mines, namely the Champion Reef Mine, the Mysore Mine, the Nundydroog Mine and the Oorgaum Mine, exploited a series of parallel veins extending to depths approaching 3,000 metres below the surface, making them among the deepest underground operations in the world at the time of their peak production.

History

Pre-modern gold mining at Kolar is documented in Sangam-era Tamil literature and in the archaeological record from at least the third century BCE. The Hoysala and Vijayanagara empires worked the deposits during the mediaeval period. British commercial interest began in the 1870s with the formation of the John Taylor and Sons mining venture, which received concessions from the Maharaja of Mysore in 1881. Production grew rapidly through the late nineteenth and early twentieth centuries, peaking in the 1900s when Kolar supplied a substantial fraction of British India's gold output. After Indian independence in 1947, the mines were nationalised in 1956 under Bharat Gold Mines Limited.

Decline and closure

Kolar production declined progressively through the second half of the twentieth century as the most accessible reefs were exhausted and the operating depths became uneconomic at prevailing gold prices. Bharat Gold Mines was unprofitable for several decades before closure in 2001 under government direction. The town of Kolar Gold Fields, now Robertsonpet, has since become an industrial heritage site, with much of the surface infrastructure preserved or repurposed. The deep underground workings have been allowed to flood and are now permanently inaccessible.

Trade and gemmological relevance

From a contemporary jewellery trade perspective, Kolar is significant principally as a historical reference. Gold from Kolar in the form of small ingots and dore bars circulated in the Indian and international trade through the twentieth century without specific regional marking, and Kolar-origin material in finished jewellery cannot generally be distinguished from gold of other origins. The Kolar Gold Fields' contribution to the broader Indian goldsmithing tradition, however, was substantial, supplying the raw material for several generations of bridal and ceremonial jewellery in southern India. Artefacts and ingots of clear Kolar provenance occasionally appear in the auction market and command modest premiums for the historical interest, although the gold itself trades at the prevailing spot price.