Poldice Mine
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Poldice mine is a former metalliferous mine located in Poldice Valley in southwest
Cornwall Cornwall (; or ) is a Ceremonial counties of England, ceremonial county in South West England. It is also one of the Celtic nations and the homeland of the Cornish people. The county is bordered by the Atlantic Ocean to the north and west, ...
,
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,
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
. It is situated near the hamlet of Todpool, between the villages of Twelveheads and St Day, three miles (5 km) east of
Redruth Redruth ( , ) is a town and civil parishes in Cornwall, civil parish in Cornwall, England, United Kingdom. According to the 2011 census, the population of Redruth was 14,018 In the same year the population of the Camborne-Redruth urban area, ...
.


History

A legal document of 1512 about a theft of tin "near Poldyth in Wennap" indicates that mining was probably taking place around Poldice at that time, but this mine is certainly known to have been in operation by the 17th century. At the end of the 17th and beginning of the 18th century, 800 to 1,000 men were employed. 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
lode In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fracture (or crack) in a rock formation or a vein of ore that is deposited or embedded between layers of rock. The current meaning (ore vein) dates from th ...
s of ore. When the adit reached Poldice in the late 1760s, the mine was using two
Newcomen steam engine The atmospheric engine was invented by Thomas Newcomen in 1712, and is sometimes referred to as the Newcomen fire engine (see below) or Newcomen engine. The engine was operated by condensing steam being drawn into the cylinder, thereby creating ...
s, with cylinders of diameter 66 inches and 60 inches to drain the mine into the adit. As the mine was some distance from the sea, transport to market was a problem for the mining operation. A pioneering railway, the Portreath Tramroad was opened in 1812 giving access to Portreath harbour. In November 1821 a 90-inch Woolf single-cylinder pumping engine was installed at the mine, the third one of this size in the county, after two had been installed at Consolidated Mines in February of the same year. These were by far the largest steam engines in Cornwall at the time. In 1842 this engine was raising an average of 887 gallons per minute and it was one of the most heavily worked engines in the county.Barton 1966, p. 102 It was re-cylindered as an 85 inch in 1845 and was still working well when it was sold for £700 in August 1867 to Great Western Deep Coal Co. in the Forest of Dean. By the 1860s the copper industry was in decline, and some time between 1869 and 1872 the mine sold £12,000 worth of redundant equipment to J. C. Lanyon & Son of Redruth, a major dealer and exporter of mine equipment. Despite these sales, the mine purchased from
Perran Foundry Perranarworthal () is a civil parishes in England, civil parish and village in Cornwall, England, United Kingdom. The village is about four miles (6.5 km) northwest of Falmouth, Cornwall, Falmouth and five miles (8 km) southwest of ...
a new 85-inch pumping engine that cost £2,250 and which was in operation by early 1873. At the time it was needed to deal with the water flooding into the mine as a result of a very wet winter, but in July 1873 after working for just 6 months, the engine was up for sale and the mine had closed because it was unable to cope with the cost of pumping water out of the workings. The engine was sold to a company in Scotland.


Minerals

The mine was extracting tin ore in 1748, but by 1788 the output of copper ore exceeded that of tin, and by the 1790s it was making a good profit. In the early 19th century the mine merged with neighbour Wheal Unity. The mine switched to
arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...
extraction, although metals were still being mined in decreasing quantities, but by the 1910s most of the activity was over and although small-scale mining continued into the 1920s, it closed in 1930. Apart from the enormous quantities of the common ores mined at Poldice, the area was also known for rarer and more valuable minerals including chalcophyllite, olivenite,
mimetite Mimetite is a lead arsenate chloride mineral () which forms as a secondary mineral in lead deposits, usually by the Redox, oxidation of galena and arsenopyrite. The name derives from the Greek ''mimetes'', meaning "imitator" and refers to mimeti ...
and
liroconite Liroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula copper, Cu2Aluminium, Al OH)4, Arsenic, Asoxygen, O4·4(H2O). It is a vitreous monoclinic mineral, colored bright blue to green, often associated wit ...
.


The site today

Today, the ruins of many mine buildings and mineshafts are visible in the Poldice Valley, which has not seen any further development since the end of mining. The valley is now a nature reserve, and is a popular location for mountain bicycling.


Mineral Statistics

From Robert Hunt's ''Mineral Statistics of the United Kingdom''''.''


See also

* Consolidated Mines * Devon Great Consols * Wheal Vor * Wheal Jane *
Mining in Cornwall and Devon Mining in Cornwall and Devon, in the southwest of Britain, is thought to have begun in the early-middle Bronze Age with the exploitation of cassiterite. Tin, and later copper, were the most commonly extracted metals. Some tin mining continue ...
* Portreath Tramroad


References

* ''Poldice Valley'', Bob Acton, Landfall Publications, 1990.


Sources

* {{Cornwall, state=collapsed Arsenic mines in Cornwall Copper mines in Cornwall Tin mines in Cornwall Industrial archaeological sites in Cornwall