Web: www.cornish-mining.org.uk
Mining in Cornwall began in the early Bronze Age approximately 2,150 BC and ended with the South Crofty tin mine closing in 1998. Tin and later also copper were the most productive of the metals extracted: some tin mining continued long after mining of other metals had become unprofitable.
Historically extensive tin and copper mining has occurred in Cornwall, as well as arsenic, silver, zinc and a few other metals. Now there are no active metalliferous mines remaining. However, tin deposits still exist in Cornwall, and there is talk of re-opening South Crofty tin mine. Geological studies were made worthwhile due to the economic importance of mines and quarries: about forty distinct minerals have been identified from type localities in Cornwall, e.g. endellionite from St. Endellion. Quarrying of the igneous and metamorphic rocks has also been a significant industry: in recent times the extraction of kaolin has been the most important economically.
Cornwall provided most of the United Kingdom's tin, copper and arsenic until the 20th century. Originally the tin was found as alluvial deposits in the gravels of stream beds, as still preserved at Tolgus Tin, but eventually underground working took place. Tin lodes outcropped on the cliffs and underground mines sprang up as early as the 16th century.
There are few remains of prehistoric tin mining in Cornwall, probably because later workings have destroyed early ones. However, shallow cuttings used for extracting ore can be seen in some places. There are a few stone hammers, such as those in the Zennor Wayside Museum. It may well be that mining was mostly undertaken with shovels, antler picks and wooden wedges. There have been finds of tin slag on the floors of Bronze Age houses, for example at Trevisker.
In the Iron Age bronze continued to be used for ornaments though not for tools and weapons, so tin extraction seems to have continued. An ingot from Castle Dore is probably of Iron Age date.
The tin resources are said to have been a reason why the Romans invaded Britain but they had control of mines in Spain and Brittany in the first and 2nd centuries. Later production in Spain was curtailed, probably by raiding. Production in Britain increased in the 3rd century, for use in coinage, and there was extensive use of tin in pewter manufacture. West Devon and Cornwall are areas which are less Romanised than many other parts of England and it may be tin mining was in local hands with tin purchase by the imperial authority. A possible official stamp has been identified on the Carnington tin ingot.
St. Piran (patron saint of tinners) is said to have landed at Perranporth from Ireland about 420 AD.
There is no record of tin mining in Domesday Book, possibly because the rights were Crown Property. For the first half of the 12th century Dartmoor provided most of the tin for Europe, exceeding the production of Cornwall. The Pipe Roll of Henry II gives the annual tin production of Dartmoor to be about 60 tons. In 1198 he agreed that "all the diggers and buyers of black tin, and all the smelters of tin, and traders of tin in the first smelting shall have the just and ancient customs and liberties established in Devon and Cornwall." This shows that mining had been going on for a long period by this time. A charter confirming the miners' rights was granted by King John in 1201.
In 1305 King Edward I established separate Stannaries for Devon and Cornwall to administer the law. Water was used to operate "stamps" to crush the ore, the lighter waste being washed away. The mineral "black tin" was placed in furnaces and layered with peat. The molten metal was poured into granite moulds which produced ingots of tin. These were taken on pack horses to the Stannary towns for assaying. Usable deposits in Devon became worked out and so Cornwall was then the center of tin production. In 1337 Cornish tin production was 650 tons but in 1335 it had been reduced to 250 tons by the Black Death. In 1400 Cornish production rose to 800 tons. The production in Devon was only 25% of that of Cornwall in 1450-70.
The Cornish Rebellion of 1497 originated among Cornish tin miners who opposed the raising of taxes by Henry VII in order to make war on Scotland. This levy was resented for the economic hardship it would cause; it also intruded on a special Cornish tax exemption. The rebels marched on London, gaining supporters as they went, but were defeated at the Battle of Deptford Bridge.
Quarrying was of very limited importance in medieval Cornwall. Stone for church building was very rarely imported from outside the county but most church building was in whatever stone could be brought for short distances. For some ornamental features such as doorways, pillars and fonts good use was made of varieties of elvan e.g. Polyphant and Catacleuze. The granite was not quarried but collected from the moorlands and worked on site. Quarrying of slate developed in north Cornwall in the later Middle Ages and later developed in early modern times into larger undertakings.
A second tin boom came around the 16th century when open cast mining was used. German miners came in who had knowledge of the new techniques. A third boom occurred in the 18th century when shafts were dug to extract the ore.
However it was in the 19th century that mining reached its zenith, before foreign competition depressed the price of copper, and later tin, to a level that made Cornish ore unprofitable. The areas of Cornwall around Gwennap and St. Day and on the coast around Porthtowan were among the richest mining areas in the world and at its height the Cornish tin mining industry had around 600 steam engines working to pump out the mines (many mines stretched out under the sea and some went down to great depths). Adventurers put up the capital, and the mines would hopefully return them a profit.
In 1748, Poldice's chief adventurer William Lemon and manager John Williams started the Great County Adit in the Carnon Valley. It formed a cheap and effective method of draining many of the mines in the locality and also provided a means of locating new lodes of ore. When the adit reached Poldice in the late 1760s, the mine was using two Newcomen steam engines to drain the mine into the adit.
Caradon Hill had the most productive mine in east Cornwall. The South Caradon Copper Mine, 1km to the SW of the transmitter, was the largest copper mine in the UK in its heyday, 150 years ago. Captain James Clymo and the Kittow family acquired the lease for the area and started an adit running eastwards from the Seaton Valley. Despite shortage of resources the miners continue to persevere in extending the adit, following promising signs of ore deeper into the hill. It took them three years to strike copper. The mine was soon producing over 5,000 tons of ore a year and employing 600 people. The area around Caradon hill was said to resemble the gold rush mining camps of the Western USA. The world price of copper dropped in the 1860's eventually closing the many mines. Other disused copper and tin mines are scattered around the base of the hill and the village of Minions. By the mid-19th century Looe had become a major port, one of Cornwall's largest, exporting local tin, arsenic and granite, as well as hosting thriving fishing and boatbuilding industries. Menheniot was a centre of lead mining and is now surrounded by disused shafts and engine houses. Lead seams were discovered in the 1840s and Menheniot became the centre of a mining boom which lasted until the 1870s. During this period the population doubled. Kit Hill Country Park is steeped in mining history. Metals extracted included, tin, silver, copper and wolfram. The main mines were Kit Hill Summit Mines (which included a windmill near the present stack) (started about 1826; Kit Hill United closed in 1864); East Kit Hill Mine, worked from 1855 to 1909; Hingston Down mine (which worked westwards towards Kit Hill, may have started in the 17th century, it closed in 1885; and South Kit Hill Mine, worked from 1856 to 1884.
The last Cornish Stannary Parliament was held at Hingston Down in 1753. The Stannary Courts were formally abolished in 1836.
By the middle and late 19th century, Cornish mining was in decline, and many Cornish miners emigrated to developing mining districts overseas, where their skills were in great demand: these included South Africa, Australia and North America. Cornish miners became dominant in the 1850s in the iron and copper districts of northern Michigan in the United States, as well as in many other mining districts. In the first 6 months of 1875 over 10,000 miners left Cornwall to find work overseas.
During the 20th century various ores became briefly profitable, and mines were re-opened, but today none remain. Dolcoath mine, (Cornish for Old Ground), the 'Queen of Cornish Mines' was, at a depth of 3500 feet (1067 m), for many years the deepest mine in the world, not to mention one of the oldest before its closure in 1921. Indeed, the last working tin mine in Europe, South Crofty, was to be found near Camborne until its closure in March 1998. An attempt was made to re-open it but the mine was then abandoned.
In 1992 Geevor Mine was acquired by Cornwall County Council as a Heritage Museum, which is now run by Pendeen Community Heritage. Both Geevor Tin Mine and Morwellham Quay in Devon have been selected as "anchor points" on the European Route of Industrial Heritage.
The extraction of china clay continues to be of considerable importance: the larger works are in the St. Austell district. The amount of waste in proportion to kaolin is so great that huge waste mounds were created whose whiteness in the early years means that they can be seen from afar. The Eden Project has been developed on the site of a former china clay quarry. Extraction of slate and roadstone by quarrying still continues on a reduced scale: it was formerly an important industry and it has been carried on in Cornwall ever since the Middle Ages. Several quarries have been productive enough to need their own mineral railways. Granite of high quality has been extracted from many Cornish quarries such as De Lank, Porthoustock and Delabole, and some has been taken very long distances for use in building.
In the metalliferous mines of Cornwall, some of the worst accidents were at East Wheal Rose in 1846, where 39 men were killed by a sudden flood; at Levant Mine in 1919, where 31 were killed and many injured in a failure of the man engine; 12 killed at Wheal Agar in 1883 when a cage fell down a shaft; and seven killed at Dolcoath Mine in 1893 when a large stull collapsed.
Cornwall has long had mines for tin, copper and other metal ores, but if mining is to take place below adit, means must be found of draining the mine. This may be done using horse power or a waterwheel to operate pumps, but horses have limited power and waterwheels need a suitable stream of water. Accordingly, the conversion of coal into power to work pumps was highly desirable to the mining industry.
A Cornish engine is a type of steam engine developed in Cornwall, mainly for pumping water from a mine. It is a form of beam engine that uses steam at a higher pressure than the earlier engines designed by James Watt. The engines were also used for powering man engines to assist the underground miners' journeys to and from their working levels, for winching materials into and out of the mine and for powering the ore stamping machinery.
A Cornish engine pumps by a falling weight that is lifted by the engine. Few remain in their original locations, the majority having been scrapped when their related industrial concern closed.
Wheal Vor (mine) had one of the earliest Newcomen engines before 1714, but Cornwall has no coalfield and coal imported from south Wales was expensive. The cost of fuel for pumping was thus a significant part of mining costs. This meant that many early Watt engines were erected by Boulton and Watt in Cornwall. They charged the mine owners a royalty based on a share of the fuel saving. The fuel-efficiency of an engine was measured by its "duty", expressed in the work (in foot-pounds) generated by a bushel (94 pounds) of coal. Early Watt engines had a duty of 20 million; later ones over 30 million. The Yorkshire engineer John Smeaton also took the Newcomen design and made significant design improvements.
The Cornish engine depended on the use of steam at above atmospheric pressure, as devised by Richard Trevithick in the 19th century. Trevithick's early "puffer" engines discharged steam into the atmosphere. This differed from the Watt steam engine, which depended solely on the creation of a vacuum when steam was condensed. Trevithick's later ones (in the 1810s) combined the two principles, starting with high pressure steam but also condensing it in a separate condenser. In a parallel development Arthur Woolf developed the compound engine, in which the steam expanded in two cylinders successively.
When Trevithick left for South America in 1816 he passed his patent right to his latest invention to William Sims, who built (or adapted) a number of engines, including one at Wheal Chance (operating at 40 pounds per square inch above atmospheric pressure, which achieved a duty of nearly 50 million, but its duty then fell back. A test was carried out between a Trevithick type single-cylinder engine and a Woolf compound engine at Wheal Alfred in 1825, when both achieved a duty of slightly more than 40 million.
The next improvement was achieved in the late 1820s by Samuel Grose, who decreased the heat loss by insulating the pipes, cylinders, and boilers of the engines, improving the duty to more than 60 million at Wheal Hope and later to almost 80 million at Wheal Towan. Nevertheless, the best duty was usually a short-lived achievement due to general deterioration of machinery, leaks from boilers, and the wearing out of boiler plates (meaning that pressure had to be reduced).
Minor improvements increased the duty a little further, but the engine seems to have reached its practical limits by the mid-1840s. With pressures of up to 50 pounds per square inch, the shocks are likely to have caused machinery breakages. The same improvements in duty occurred in engines operating Cornish stamps and whims, but generally came slightly later. In both cases the best duty was lower than for pumping engines, particularly so for whim engines, whose work was discontinuous.
The impetus for the improvement of the steam engine came from Cornwall because to the high price of coal there, but both capital and maintenance costs were higher than a Watt steam engine. This long delayed the installation of Cornish engines outside Cornwall. A second hand Cornish engine was installed at East London Waterworks in 1838, and compared to a Watt engine with favourable results, because the price of coal in London was even higher than in Cornwall. However, in the main textile manufacturing areas, such as Manchester and Leeds, the coal price was too low to make replacement economic. Only in the late 1830s did textile manufacturers begin moving to high pressure engines, usually by adding a high pressure cylinder, forming a compound engine, rather than following the usual Cornish practice.
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