Poldice
Encyclopedia
Poldice mine is a former metalliferous mine located in Poldice Valley in south-west Cornwall
, England
, United Kingdom
. It is situated near the hamlet of Todpool
, between the villages of Twelveheads
and St Day
, three miles (5 km) west of Redruth
.
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
s of ore. When the adit reached Poldice in the late 1760s, the mine was using two Newcomen steam engine
s, with cylinders of diameter 66 inches and 60 inches to drain the mine into the adit.
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. 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.
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.
, olivenite
, mimetite
and liroconite
.
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
. It is situated near the hamlet of Todpool
Todpool
Todpool is a hamlet in south-west Cornwall, United Kingdom. It is located between Chacewater and St Day villages and is three miles east of Redruth....
, between the villages of Twelveheads
Twelveheads
Twelveheads is a hamlet in Cornwall, England, in the United Kingdom. It lies between Truro and Redruth.Twelveheads has a small Methodist chapel; Billy Bray, the Methodist preacher, was born here. The former village pub and post office are both now private housing.The name comes from the hamlet's...
and St Day
St Day
St Day is a civil parish and village in Cornwall, United Kingdom. It is situated between the village of Chacewater and the town of Redruth.St Day is located in a former mining area and St Day accrued considerable wealth from mining...
, three miles (5 km) west of Redruth
Redruth
Redruth is a town and civil parish traditionally in the Penwith Hundred in Cornwall, United Kingdom. It has a population of 12,352. Redruth lies approximately at the junction of the A393 and A3047 roads, on the route of the old London to Land's End trunk road , and is approximately west of...
.
Early 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.The Great County Adit
In 1748, Poldice's chief adventurer William Lemon and manager John Williams started the Great County AditGreat County Adit
The Great County Adit, sometimes called the County Adit, or the Great Adit was a system of interconnected adits that helped drain water from the tin and copper mines in the Gwennap area of Cornwall, in the United Kingdom...
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
Lode
In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fissure in a rock formation or a vein of ore that is deposited or embedded between layers of rock....
s of ore. When the adit reached Poldice in the late 1760s, the mine was using two Newcomen steam engine
Newcomen steam engine
The atmospheric engine invented by Thomas Newcomen in 1712, today referred to as a Newcomen steam engine , was the first practical device to harness the power of steam to produce mechanical work. Newcomen engines were used throughout Britain and Europe, principally to pump water out of mines,...
s, with cylinders of diameter 66 inches and 60 inches to drain the mine into the adit.
Tin and copper
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.Woolf pumping engine
In November 1821 a 90 inch WoolfArthur Woolf
Arthur Woolf was a Cornish engineer, most famous for inventing a high-pressure compound steam engine. As such he made an outstanding contribution to the development and perfection of the Cornish engine.Woolf left Cornwall in 1785 to work for Joseph Bramah's engineering works in London...
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
Consolidated Mines
Consolidated Mines, also known as Great Consolidated mine, but most commonly called Consols or Great Consols was a metalliferous mine about a mile ESE of the village of St Day, Cornwall, England. Mainly active during the first half of the 19th century, its mining sett was about 600 yards...
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. 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.
Difficult times
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 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 six 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.Arsenic
The mine switched to arsenicArsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
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.
Other minerals
Apart from the enormous quantities of the common ores mined at Poldice, the area was also known for rarer and more valuable minerals including chalcophylliteChalcophyllite
Chalcophyllite is a rare secondary copper arsenate mineral occurring in the oxidized zones of some arsenic-bearing copper deposits. It was first described from material collected in Germany...
, olivenite
Olivenite
Olivenite is a copper arsenate mineral, formula Cu2AsO4OH. It crystallizes in the monoclinic system , and is sometimes found in small brilliant crystals of simple prismatic habit terminated by domal faces...
, mimetite
Mimetite
Mimetite, whose name derives from the Greek Μιμητής mimethes, meaning "imitator", is an arsenate mineral which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite. The name is a reference to mimetite's resemblance to the mineral pyromorphite...
and liroconite
Liroconite
Liroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula Cu2Al[4|AsO4]·4. It is a vitreous monoclinic mineral, colored bright blue to green, often associated with malachite, azurite, olivenite, and clinoclase...
.