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Gunnislake Clitters copper, tin, arsenic and wolfram mine

List Entry Summary

This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Culture, Media and Sport.

Name: Gunnislake Clitters copper, tin, arsenic and wolfram mine

List entry Number: 1017088

Location

The monument may lie within the boundary of more than one authority.

County:

District: Cornwall

District Type: Unitary Authority

Parish: Calstock

National Park: Not applicable to this List entry.

Grade: Not applicable to this List entry.

Date first scheduled: 08-Sep-2003

Date of most recent amendment: Not applicable to this List entry.

Legacy System Information

The contents of this record have been generated from a legacy data system.

Legacy System: RSM

UID: 15545

Asset Groupings

This list entry does not comprise part of an Asset Grouping. Asset Groupings are not part of the official record but are added later for information.

List entry Description

Summary of Monument

Legacy Record - This information may be included in the List Entry Details.

Reasons for Designation

For several millennia the south west peninsula has been one of the major areas of non-ferrous metal mining in England, its more important and prolific products including copper and tin, along with a range of minor metals and other materials, notably arsenic, which occur in the same ore bodies. Before the 16th century, exploitation of this region's non-ferrous metal resources almost exclusively involved tin. Extraction focussed along valley floors and hillslopes on and around the granite uplands of the south west where tin ore, cassiterite, had accumulated after natural erosion from the parent lodes. These accumulations were exploited by streamworks, using carefully controlled flows of water to expose and then concentrate the ore, leaving behind distinctively deepened valley floors with various patterns of spoil heaps, together with extensive water management features and downstream silting. By this method, Dartmoor became Europe's chief source of tin in the 12th century with a further peak of production between about 1450 and 1550. By the early post-medieval period, most substantial deposits susceptible to streamworking had been exhausted and the focus of exploitation transferred to the mineralised lodes themselves, a change which also marks the appearance of copper as an important product of the south western mining industry. The early post-medieval extraction from lodes was restricted by the ability to drain the cut, resulting in relatively shallow workings directly into lode exposures at the bedrock surface, often by pits, called 'lode-back pits', sometimes enlarged to form longer openworks along the lodes. Tin ore from later medieval and early post-medieval extraction sites was processed and smelted using water-powered tin mills sited nearby. In the 18th century, ore extraction and processing rapidly expanded to meet growing demands, aided and promoted by technological development, with ore shipped to Bristol and later South Wales for smelting. Surface workings became larger and more extensive, and deeper extraction was achieved from shafts, the water pumped from larger mines by early steam engines or drained through near-horizontal tunnels called adits which also served to access the lodes. Horse powered winding engines lifted ore from the shaft while larger and more efficient waterwheels served ore processing areas. By such means, west Cornwall became England's main producer of copper ore in the 18th-early 19th century. Intensification accelerated in the late 18th-early 19th century with more efficient steam powered pumping engines allowing deeper shafts from which extensive underground workings spread out. By the mid-19th century, steam also powered winding and ore processing operations, the engines, boilers and ancillary machinery housed in distinctive masonry buildings grouped around the main shafts and dressing areas. Later in the century, compressed air was used for underground extraction equipment, fed from steam powered compressors on the surface. Ore processing became increasingly mechanised, along with the development of more effective methods of separating and retaining different ores, particularly in the production of arsenic which became a major saleable product in the 19th century, with the south west mines forming the world's main producer. The transport systems serving mines was also revolutionised in the 19th century, with tramways replacing packhorse and cart tracks; later, railways were built specifically to provide fuel and materials to mines and to export their ore. With these advances, east Cornwall and west Devon became one of the world's main sources of copper ore until the later 19th century, while in west Cornwall the copper ores became exhausted and replaced as that area's main product by the tin ores present at deeper levels. From the 1860s, the south western mining industries declined with competition from cheaper sources of copper and tin ore overseas, especially from South America, leading to a major economic collapse and widespread mine closures in the 1880s. Limited ore extraction continued into the 20th century, some from shaft mining, but attention mostly turned to reprocessing spoil from earlier mines. Among the developments to make these activities cost effective, electric power and internal combustion engines increasingly replaced steam for ore processing, winding and pumping in the early 20th century, activities which were housed in large framed sheds rather than masonry structures. Ore processing underwent further advance and the invention of electro-magnetic separators enabled efficient extraction of the tungsten ore wolfram. Urgent demands for metals during the First and Second World Wars led to the reopening of several mines and reprocessing mills, with wolfram a particularly important ore, but slumping ore prices between and since the wars curtailed any profitable development of these enterprises.

The 19th-early 20th century mine at Gunnislake Clitters has a good range of surviving remains from an unusually long sequence of operational phases, spanning much of the most intensive period of metalliferous mining in Cornwall. The upstanding features and buildings are complemented by areas of the mine's early processing activities sealed beneath the later dumps. The dumps themselves, from the various phases, are of particular importance in preserving particle size and colour differences denoting their functional association with the surviving processing structures from which they derive. The successive remains in this scheduling demonstrate clearly the varied impacts of technological development in extractive and ore processing methods throughout the mine's operational life, to the extent of adding a further ore, wolfram, to the mine's main products during the early 20th century. Such development is also clearly evident in the remains of the mine's supporting infrastructure: the appearance of complexes of masonry buildings in the mid- 19th century and their replacement with large framed sheds in the early 20th century; the extensive (though not total) replacement of water power by steam power in the 1860s and the installation of electric power in the early 20th century, and the replacement of trackways with tramways and the arrival of the railway at the edge of the mine's area in the later 19th century. These developments and the mine's periods of prosperity and closure also partly reflect changes in funding strategies and the wider economic context in which the mine operated, aspects which are well recorded for this mine in a wealth of historical documentation.

History

Legacy Record - This information may be included in the List Entry Details.

Details

The monument includes the remains of the Gunnislake Clitters Mine, a 19th-early 20th century copper, tin, arsenic and wolfram mine on a steep slope down to the River Tamar 1km WNW of Gunnislake village in south east Cornwall. The riverside pumping engine house and chimney in this scheduling are listed Grade II. The scheduling is divided into four separate areas of protection. The earliest visible remains on this steep slope south of the River Tamar are scattered early post-medieval workings within and beyond the scheduling, including deep openworks, pits and small shafts dug into the mostly east-west mineralised lodes. More intensive mining activity began about 1820: a long tunnel called an adit was driven south into the foot of the slope near the river, reaching over 900m in length. Cutting across successive lodes, it gave access to and drained water from workings and shafts extending from it. This early stage of the mine, called `Were Fox', had dressing floors and spoil dumps beside the adit entrance in an area now masked by later dumps. A water wheel in the adit outflow powered dressing floor machinery and drove a fan to clear air in the mine. An underground waterwheel was later installed to pump water up to the adit from working levels extending below river level. By the time operations ceased in 1827 it had produced 40 tons of copper ore. Reopening as the `Clitters Adit' mine in 1858 and renamed the `Gunnislake Clitters' mine in 1877, it continued production of copper, tin and arsenic until closure in 1889 at a time of widespread economic failure of Cornish mining. In this highly productive phase, the mine sold 32,686 tons of copper ore from 1860 to 1890 and 123 tons of tin ore from 1867 to 1873. Extraction, crushing and primary dressing were focussed around Skinner's Shaft, sunk deep into the main lode from the hillside 450m south of the original adit. Final ore dressing and concentration, and arsenic production, were sited over the lower slope behind the early phase adit. Extensive remains from this phase survive in both areas. Skinner's Shaft itself, eventually sunk to over 500m deep, is enclosed by a rectangular rubble wall with dressed quoins. In 1862-1864, steam engines were installed for pumping, winding and ore crushing, in engine houses which survive extensively at the Skinner's Shaft complex. The pumping engine house, north west of the shaft, is adjoined to the north by the largely intact walls and one extant gable of the boiler house which served all three engine houses in this complex. A building by the boiler house is identified as a miners' dry, where clothing was dried between shifts. A tall detached chimney serving the boiler house rises 20m to the west, largely of mortared rubble but with a brick-built upper quarter. The winding engine house is 13m north east of the shaft, with a partly demolished ore crusher house close to the south east. A building complex south west of the shaft includes the Account House, with a bay window facing east, and buildings and a yard identified as the carpenters' workshops and store. Extending 75m east from Skinner's Shaft is a large dressing floor, terraced along the slope and revetted by tall rubble walls; a map of 1883 shows the floor occupied by a long shed which has not survived. East of the dressing floor, a row of six small rectangular settling tanks survives, silted but with sluice gaps evident in their downslope walls; incomplete remains also survive from one of two larger tanks shown nearby on the 1883 map. South of the dressing floor's east end, an ore crusher building survives substantially intact and was powered from an engine house surviving adjacent to the south west beside the Dimson to Chilsworthy road. South of that road, walls survive of the 1860s miners' dry and smithy, alongside the levelled platform of a former forge. East of these buildings, the 1883 map shows reservoir ponds serving the boiler house; no remains of these are now visible. Extensive spoil dumps cover much of the hillslope below the Skinner's Shaft complex, down to the Dimson to Bitthams road. Early photographs and the 1883 map show them as much larger than they now survive and forming long `finger dumps' supporting tipping tramways emanating from the north of the dressing floor and the ore crusher by the Skinner's winding house. Their present extent results from 20th century reprocessing but the various dumps retain their differing particle sizes and colours corresponding to the stage of ore processing from which they derive. The west of the Skinner's Shaft dressing floor was linked to the lower slope dressing floors and arsenic works by a tramway between two finger dumps and extending north of the Dimson to Bitthams road. It does not survive south of that road but about 90m of its course remains visible north of the road as a rubble-faced embankment running to a cutting before the truncation of its northern end by the western tramway of the 1900-1909 works. The lower slope operations were sited on terraces retained by high revetment walls. The 1883 map shows two rows of rotating waste/ore separators called buddles: six on an upper level and three below, associated with settling tanks. At the east of this complex, arsenic extraction structures were linked by a tortuous flue called a labyrinth to one of two detached chimneys. The 20th century reprocessing works and its dumps masked and partly removed a number of these lower slope features of the 1860s-1880s phase. The terraces survive well, as do the two chimneys and a reservoir, still water-filled, which supplied water to the dressing floor. Masonry survives from several buildings near the western chimney and others associated with the arsenic works further east, but the buddles, settling tanks and arsenic labyrinth were variously dumped over or removed by the later activity. Below the lower dressing floor is the 1860s smithy and office, with walls and chimney extensively intact. Close to the north, by the river, are extensive remains of another complex comprising a pumping engine house, adjacent boiler house, detached chimney and two settling tanks. These were built in 1882 to supply clean river water to the Skinner's Shaft boiler house and to augment water supply to the lower slope dressing floor. By then, the Clitters Adit outflow had been diverted 25m to the east, passing over a waterwheel before joining the river. The 1882 engine house was built over the wheel pit, which was left open and through which the adit outflow still passes. Water was fed to the engine house by a leat cut along the riverside and taken off the river at a weir 175m upstream of the engine house. The main export route for the mine's ore in the 1860s-1880s was a track from the lower dressing floors to the riverside and on, beyond this scheduling, to the head of the Tamar Navigation at Gunnislake. From at least 1872 and possibly earlier, the East Cornwall Mineral Railway ran from above the important quay at Calstock, passing south of the Skinner's Shaft complex, where sidings in this scheduling were built to unload materials required in the mine's operation. In 1900, a new company, Clitters United, amalgamated this mine with three others nearby. Minor underground work required a small powder magazine which survives upslope from the Clitters adit but the main investment lay in a large ore reprocessing mill built on the lower slope in this scheduling, east of the earlier lower dressing floor. It housed the latest electric powered equipment for extracting tin, wolfram and arsenic from spoil dumps around this and other nearby mines, especially from the Greenhill arsenic works on the upper slope beyond Skinner's Shaft. The mill's surviving remains extend across five revetted terraces, to 50m long, supporting concrete floors and an array of rendered machine bases. Contemporary photographs give external and internal views showing the mill's now demolished structure of timber and girder framed sheds with corrugated sheet walls pierced by rows of windows. Coarse waste was carried west by a short tramway and dumped over the buddles and tanks of the earlier lower slope dressing floor. A new dressing floor was built near the mill, its terraces surviving with two pairs of buddles and the wheel pit from which they were driven. Fine waste tailings were taken west of the 1882 riverside engine house and settling tanks to form a massive dump, 100m long, towering above the riverside. East of the dressing floor, surviving terraces of an ore drying plant support its kiln, white brick chimney and tank. South west of the mill's dressing floor was the focus of arsenic extraction; surviving remains include a Brunton calciner retaining its brick arched lower vault, hearth bed, central spindle, drive gear and lower bearing plinth. From there, the arsenic flue reuses elements of the earlier flue and passes beneath the floor levels of several buildings in its circuitous route to the western of the earlier chimneys. Steep inclined tramways brought ore and other materials to the mill and carried dressed ore from it. A western tramway rose from above the mill, passing 75m west of Skinner's Shaft, to enlarged sidings by the railway line above; its crossing over the nearby road is marked by a tall masonry abutment on the south. Its course down the slope remains clearly visible, with embankments and cuttings to smooth its gradient. An eastern tramway, also still visible, rose from above the mill to a blocked adit by the Dimson to Bitthams road; several lengths of tram rail survive as fence posts along a nearby field wall to the west. A third tramway descends to the riverside from the lower end of the eastern tramway, on almost the same alignment, and met a tramway along the former riverside track to Gunnislake. The reprocessing works produced 547 tons of tin ore and 443 tons of wolfram between 1902 and 1908 but it ceased operation in 1909. Following the outbreak of war in 1914, the mine was reopened for reprocessing ore for wolfram and tin. Some underground work was carried out but most ore derived from existing spoil dumps as before, supplemented by ore brought by aerial ropeway from reopened mines on Hingston Down and Kit Hill, beyond this scheduling to the WSW. The ropeway was supported on shuttered concrete stanchions; the two nearest the mine, in the south west of this scheduling, carried the ropeway over the railway line. By 1919 the mine had produced 37 tons of tin ore but slumping prices after the war led to final closure of the mine in the late 1920s. The modern fences, gates, signs, signposts, goat sheds, and goat and poultry keeping equipment are excluded from the scheduling, although the ground beneath them is included.

MAP EXTRACT The site of the monument is shown on the attached map extract.

Selected Sources

Books and journals
Sharpe, A, Duchy of Cornwall Industrial Sites: A Survey, (1989)
Smith, J R, Sharpe, A , Duchy Mineral Survey, (1985)
Other
Buck, C, Gunnislake Clitters Archaeological Assessment, 1998, Unpubl Rept for C/wall County Council
Title: 1:10000 Ordnance Survey Map; SX 47 SW Source Date: 1987 Author: Publisher: Surveyor:

National Grid Reference: SX 41981 71951, SX 42109 71912, SX 42167 72271, SX 42205 71995

Map

Map
© Crown Copyright and database right 2017. All rights reserved. Ordnance Survey Licence number 100024900.
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End of official listing