The Kolar Gold Fields

Three kilometres down, and a neutrino laboratory at the bottom

For a century this was India’s gold, mined from some of the deepest shafts on Earth, about 100 kilometres from Bengaluru in Karnataka. The workings ran to over three kilometres down, hot and cramped, and the field had one of India’s first power stations built for it in 1889 to run the hoists and the pumps. The mines closed on 28 February 2001 when the gold price no longer paid for the depth, though gold is still in the rock. The town of Robertsonpet grew around the company and its people are still there. The deep tunnels had a second life that almost nobody expects: from the 1960s to 1992 physicists used them as a laboratory shielded by three kilometres of rock, and the Kolar experiments recorded some of the first atmospheric neutrino interactions ever seen.