Wheal Jane sits near Baldhu and Chacewater in West Cornwall, in a district that has been worked for tin probably since the mid-18th century, and almost certainly since long before that on a smaller scale. The country rock here is killas, intruded by Cornubian granite, and the ore lodes carry not just tin but arsenic, copper, silver and zinc, the usual polymetallic blend that forms in veins around cooling granite plutons. By around 1885 most of the nearby mines were uneconomic. Wheal Jane held on a few more years on its arsenic revenue, then closed around 1895. It reopened in 1906 as part of Falmouth Consolidated under a modernisation programme, then closed again within a decade. In the lead-up to the Second World War the operators reworked the old spoil heaps for tin until 1946. The mine reopened a final time in 1969 with new underground development and a modern processing plant. Ownership eventually passed to Rio Tinto Zinc.

On 24 October 1985 the International Tin Council, which had quietly stabilised world tin prices since the 1950s, ran out of money to support the market. The buffer-stock manager defaulted. Tin prices collapsed from about 8,500 pounds a tonne to less than 4,000 in a few weeks. The London Metal Exchange suspended tin trading for years. Cornwall's last working tin mines - Geevor on the north coast, South Crofty near Camborne, Pendarves and Wheal Jane - faced an instant existential crisis. Wheal Jane staggered on under various rescue schemes, but it never recovered. In early January 1992 the pumps were finally switched off. Geevor closed in 1990. South Crofty held out until 1998, marking the official end of working tin mining in Britain, an industry that had sent Cornish miners around the world for three thousand years.

The pumps had been doing more than just keeping the mine workable. They had been holding back the groundwater that wanted to refill it. Without them, water rose through the abandoned workings, washing over freshly exposed rock faces, picking up acid mine drainage and dissolved metals. On 13 January 1992 it overtopped the existing drainage system, escaped into surface watercourses, and roared into the Carnon River and on toward Falmouth Bay. Fish died. Wildfowl were contaminated. The water at Restronguet Creek turned a chemical orange that became one of the defining environmental images of British mining's collapse. Emergency lime treatment began within days. By 1994 large settling ponds were operational, where the acid water is now neutralised with lime, allowing the dissolved metals to settle as a thick rust-coloured sludge. The treatment plant has run continuously ever since.

These were, the Wikipedia entry on Wheal Jane drily notes, the days before Environmental Impact Assessments. The Carnon Valley plume forced new thinking about how abandoned mines should be closed, what reserves should be set aside for ongoing water treatment, and who pays when the closure plan was made by companies long since dissolved. By 2002 the public bill for treating Wheal Jane's water had passed twenty million pounds. The site itself has become an industrial estate, the old surface buildings repurposed, the underground workings still slowly equilibrating. Specimens of beautiful blue-green ludlamite on quartz come out of the Wheal Jane spoil and end up in mineral collections worldwide. The mine that gave Cornwall its last tin gave the country a lasting reminder that closing a mine is not the same as making it go away. The orange water still flows. It is now just being filtered.