|Ag – Silver||As – Arsenic||Au – Gold||Cu – Copper|
|Mn – Manganese||Pb – Lead||Sn – Tin||W – Tungsten|
Cornwall & Devon
These counties are rich in a variety of metal ores, and are the UK’s only source of tin. It was found in veins associated with five major granite intrusions (Land’s End, Carnmenellis, St Austell, Bodmin Moor and Dartmoor) and eleven small ones (St Michael’s Mount, Tregonning-Godolphin, Carn Brea, Carn Marth, St Agnes, Cligga Head, Castle an Dinas, Belowda Beacon, Kit Hill Hingston Down and Hemerdon Ball) of Lower Permian age (280 Mya). As the granites cooled metal-rich fluids from them entered faults and cooled to form mineral veins, some of which were rich in metallic sulphides, oxides or carbonates. These included: tin, copper, iron, arsenic, lead-silver, zinc, tungsten and manganese.
Tin was being worked in Cornwall and Devon up to 4000 years ago, and by mediaeval times, along with lead and wool, it was one to England’s main exports. From 1198 the Cornish tinners had royal protection for their activities and bodies called stannaries’ were established to oversee and regulate the mining, smelting and sale of tin.
Where veins outcropped, they were worked by opencuts or closely spaced, shallow shafts sunk onto them. In other areas, where veins had been eroded by weathering, granules of tin were found in the subsoil. Such deposits are called ‘shoad’ and were usually found on gently sloping valley sides, away from streams. Tinners worked these as opencasts, called stream-works, often leaving behind a distinct landscape of linear banks of overburden.
As demand for tin increased more mines were sunk and more lodes were discovered. As the workings became deeper they were troubled by water. The difficulties of draining mines sometimes led to them being abandoned prematurely, but a range of methods of overcoming flooding were developed for pumping water. Alternatively, adits were driven into the workings.
During the eighteenth century, steam engines were increasingly used for pumping and by 1812 Richard Trevithick had designed the slow-acting but powerful and economic Cornish engine. This became the principal driving force for pumps in mines, as well as water and sewage works, and the ruins of its distinctive tall, narrow houses still survive in many parts of the world.
From the late seventeenth century a lot of copper mines were also developed in Cornwall as demand for the metal grew. They prospered in the 1760s and 1770s when the Royal Navy began sheathing its ships with copper, to prevent barnacle growth and attacks by the shipworm. Nevertheless, many closed when Parys Mountain mine, on Anglesey, flooded the market with cheaper copper during the 1780s and 1790s. Cornish copper regained its importance in the early nineteenth century, however, until competition from foreign mines forced down prices from the 1860s. Some copper mines, like Dolcoath, were fortunate enough to find tin in their deeper levels and so were able to change their product, but many closed.
During the eighteenth century many small mines were amalgamated in order to give sufficient potential reserves to make it worthwhile sinking deeper shafts and installing dressing floors to crush and recover the black tin from the tinstone.
Tin mining continued into the twentieth century, but had to adopt new techniques to survive. Steam engines were replaced by electricity and many task formerly done by hand were mechanised. The mines were also amalgamated to allow them to be worked more efficiently.
The following pages refer to some of these areas in more detail:
Index of articles published by the Northern Mine Research Society, complied by Alasdair Neill
Other sites of interest:
Wheal Martyn China Clay Museum, Carthew, St Austell, Cornwall, PL26 8XG, 01726 850362
Cornish Mining World Heritage Site
A List of Mines in North Devon and West Somerset
King Edward Mine Museum, Troon, Camborne
Please note NMRS does not have any control over the contents of external websites.Return to previous page