The history of mining in Cornwall and West Devon stretches back into prehistory when the region was uniquely placed to supply the tin vital for the production of bronze and pewter in Britain. There is also strong archaeological evidence for trade between Cornwall, the eastern Mediterranean and northern Europe.
Long ago, Cornish people learned the tell-tale signs of mineralisation – the characteristic greens of oxidised copper minerals; the reds of iron-bearing rocks; the hard resistant whiteness of quartz; and the softening and erosion of other altered rocks that signalled the presence of valuable ores. They began to realise that common plants were stunted or absent where minerals occurred. Or that some species – indicator plants – alone thrived where certain minerals lay not far beneath the surface. The Cornish people dowsed, tasted the water and learned the smells of pyrite and mundic.
Picking up subtle hints from their natural environment, they developed an instinctive sense of geology long before it was written down or scientifically analysed.
Prehistoric and Roman tin works
Pebbles of ‘stream tin’ have been found at a number of prehistoric settlement sites and there is much evidence of prehistoric activity recorded from Cornish tin streamworks.
Until 1700, tin was the most important metal in the world. Cornwall and Devon had Britain’s only indigenous tin resource and were also the principal sources for countries in northern Europe (though in the first centuries BC and AD, the Mediterranean region may have obtained their supplies from Iberia).
Tin production was probably the main reason that the Romans ventured into this part of the Celtic kingdom of Dumnonia. The nearest Roman town was Exeter, in Devon, but small forts have been found in Cornwall, together with Roman milestones and hoards of Roman coins. A Roman fort at Tregear (Nanstallon) near Bodmin is close to an ancient ford and some important early tin works.
Medieval tin streaming and shallow shaft mining
The tin streams of Cornwall and Devon sustained an internationally important medieval tin industry. Shallow mining effectively mapped the major areas where tin occurred; copper at this time still being of little commercial interest.
Tin streaming and shallow shaft mining provided employment and wealth far beyond that to be expected from such a remote and poor agricultural area.
Countless valleys in Cornwall and West Devon were turned over for tin.
There is massive evidence of tin streaming found in hundreds of hectares of man-made landforms on Dartmoor, Bodmin Moor, West Penwith, Goss Moor, Breney Common and Redmoor – as well as in the wooded valleys of the region that drain the mineral rich areas. These remains are well documented and many have been surveyed in detail. An oak tinner’s shovel found in Boscarne tin stream (Bodmin Moor) has been radiocarbon dated to between AD635 and AD1045.
The importance of the tin industry in the medieval period was recognised by the establishment of a special legal framework. It was first set out in a charter from King John in 1201 that included a number of pre-existing common law practices. The charter gave privileges to the tinners and their industry, in return for which they paid a special tax to the Crown known as ‘coinage’. This tax was calculated when all the refined tin from the district was brought to be weighed, tested for quality and stamped before being sold. The testing involved cutting off a corner or ‘coign’ from each ingot to assay its tin content, thus leading to the term coinage. From the earliest records in the 12th century through to its abolition in 1838, the tax on tin production in Cornwall was levied at double the rate of that applied in Devon.
Early underground mining
True underground mining was first documented in the Crown-operated silver mines of the Bere Alston peninsula during the late 13th century. But it was not until the early 16th century, when the tin gravels of west Cornwall were approaching exhaustion, that tinners were forced to turn to the parent lodes, most probably in what were to become the coastal mines of west Penwith.