Next time you travel from Penzance to St Just make a point of travelling upstairs on the bus, not only will you get a fantastic view of the Atlantic and the Longships from the top of Leswidden but you'll also get a bird's eye view of the site of Balleswidden Mine. While the south side of the site is dominated by the china clay pit the north side is host to another large depression about 270 feet long and 60 feet wide. This is the site of the great collapse, or fall of ground, which took place on the night of 29 January 1847. Much of the Balleswidden ground consists of soft kaolinised granite and in this instance the collapse was foreseen and no-one was injured. Cyril Noall describes the collapse as “perhaps, the largest ever known in the neighbourhood. At surface, the effects resembled a minor earthquake.”
At this point in time Balleswidden was the biggest mine in St Just with over 600 people employed above and below ground. A few years before the mine had been described as working an “inexhaustible lode”, running 144 head of steam stamps and 36 head of water stamps. In 1833-1841 it was claimed that the mine had raised £51,960 worth of black tin (£4,862,311 at today's values).
By the late 1850s Balleswidden was veering between break even and loss and the great days were over. The mine was still employing over 650 people and looking at new technologies to keep down costs. In 1856/7 they experimented with gas lighting in place of candles, an experiment which was deemed a success both technically and financially but it came to a premature end because of the financial constraints under which the mine was working. The coal gas plant, which had been acquired from Tresavean, was sold to Holman's Foundry in Nancherrow where it continued to operate until the late 1960s.
Balleswidden also operated the biggest steam engine ever worked in St Just, an 80” pumping engine acquired nearly new from Great Wheal Vor in 1860. In 1870 the engine was reported to be pumping 470 gallons a minute in the wet season, very wet by St Just standards .
The first written evidence for mining at Balleswidden is as back as 1507 when a bounds at Busvargus was registered at the Lelant Stannary Court. The mine eventually closed in 1873 though the property was resurrected as a china clay operation almost immediately afterwards. Bostraze Clay Works, at the north west end of the sett, continued working until about 1980.
Cyril Noall, The St Just Mining District, Bradford Barton, 1973
Allen Buckley, The Tudor Tin Industry, Penhellick Publications, 2009
Clive Carter, Tregaseal River, in Journal of the Trevithick Society 22, 1995