St Just and the surrounding area has been mined for copper and tin for perhaps 2000 years. Most of this was surface working, and mining as such commenced around 1820 and lasted till around 1930. The underground workings ran for a mile under the sea. Geevor mine at Pendeen was the last to close in 1990.
The geology of the area comprises slate (killas) and greenstone interspersed with granite, and laid down 280 million years ago. Granite caused tin and copper ores to be deposited in almost vertical fractures known as veins. These veins when mined are called lodes. Some 150 minerals have been found in these mines, including Botallackite, a mineral actually discovered at Wheal Cock in 1865.
- St. Just which is a very small town, is the only town in the area. Mining
families worked smallholdings the fields whose boundaries had existed for
hundreds of years.
Census returns show the effects of mining in increasing the population. St
Just increased from 2,779 in 1801 to 9,290 in 1861, with the greatest growth
occurring between 1831 and 1841. At this point mine workers made up one third
of the population in the area. However the boom did not last long, and by
the 1860’s most of the copper mines had closed and by 1900 the population
had halved. Miners and their families were forced to emigrate to get work.
Most of the lodes in the St Just area run at right angles to the coast. They
increase in value under the sea, and become less productive as one goes inland.
This is why the mining district is confined to the coastal fringe. As one
goes east from St Just, the lodes became less rich, and although there were
mines along the coast through Morvah and Zennor parishes towards St. Ives,
they were much less profitable. Inland, mining only took place at Leswidden,
and at Ding Dong, on the high moors to the east.
Thanks to the relative remoteness of the area, and the fact that little development
has taken place here since the mines closed, much of the mining archeology
has been preserved. The National Trust has in fact acquired many of the significant
sites. Geevor was bought by the Cornwall County Council in 1991 and has preserved
the existing machinery there.