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Wood Mine cobalt works and associated mines, 340m east of White Barn Farm

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: Wood Mine cobalt works and associated mines, 340m east of White Barn Farm

List entry Number: 1020181

Location

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

County:

District: Cheshire East

District Type: Unitary Authority

Parish: Alderley Edge

County:

District: Cheshire East

District Type: Unitary Authority

Parish: Nether Alderley

National Park: Not applicable to this List entry.

Grade: Not applicable to this List entry.

Date first scheduled: 10-Oct-2001

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: 33863

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

Cobalt ores usually occur as vein minerals in association with other metals, particularly nickel and copper. Although found in traces in most orefields, it is only found in workable deposits in Cornwall, at Alderley Edge (Cheshire) and in the Lake District. At Alderley Edge the ores are mostly impregnated into the local sandstone. The refined metal is used in pigments. Until the mid-19th century the pigment was produced in the form of azure or `smalt' by concentrating and then calcining the ore, then grinding and melting with fine quartz to form `zaffre', a yellow colour, named after saffron. This was then converted to azure by grinding and melting with potash. In the later 19th century a more efficient process was developed in which the parent ore containing cobalt, nickel, copper and iron was smelted to a `regulus' which was then calcined and dissolved in hydrochloric acid. The iron and copper were removed and the cobalt precipitated out with a bleaching powder, dried and heated to produce pure cobalt oxide. Copper was extracted in Britain intermittently from the Early Bronze Age (about 2000 BC) until the early 20th century, after when the industry was confined to by-product production and small scale reworkings of mines and dumps. There is very limited evidence for copper mining before the 15th and 16th centuries, and most known sites are of later date, principally of the industry's 18th and 19th century peak after it had been revitalised by developments in smelting technology. In the 18th and 19th centuries, as perhaps it had also been in prehistory, British production was important on a European scale. Nucleated copper mines are a prominent type of field monument produced by copper mining. They consist of a range of features grouped around the adits and/or shafts of a mine. The simplest examples contain merely a shaft or adit with associated spoil tip, but more complex and, in general, later examples may include remains of engine houses for pumping and/or winding from shafts, housing, lodging shops and offices and power transmission features such as wheel pits and leats. The majority of nucleated copper mines are of 18th to 20th century date, earlier mining being normally by rakes, opencuts and open levels, and including scattered ore dressing features. An essential part of a copper mining site is the ore works, where the mixture of ore and waste rock extracted from the ground was separated (dressed) to form a smeltable concentrate. The range of processes can be summarised as: picking out clean lumps of ore and waste; hammering (breaking down lumps to a smaller size by manual hammering or by mechanical crushing); jigging and buddling (separation of finer material by washing away the lighter waste in a current of water). Field remains of ore works include crushing devices, separating structures and tanks and tips of distinctive waste from the various processes, together with associated water supplies. Simple ore dressing devices had been developed by the 16th century, but the large majority date from the 18th to 20th centuries, when technology evolved rapidly. During English Heritage's national evaluation of the copper industry, 130 sites were assessed. This is a highly select sample of the numbers of sites that historically existed in England; although there are no national estimates, for the south west alone an estimate has been made of over 10,000 sites. It is considered that protection by scheduling is appropriate for less that 50, with alternative means of protection or management being considered more appropriate for the other nationally important sites. Although the cobalt processing at Alderley Edge was only working for a short time, it is historically important as an example of the discovery and application of the new 19th century technology in the preparation of metal pigments. Beneath the overgrown ground level there will be the remains of the buildings, tanks, mine workings and machinery which were associated with the production of both copper and the minor metals, lead, nickel and cobalt at this site. There are foundations of buildings, including offices, cottages, furnaces and a cooling tower which may be located and identified by further archaeological work. The site preserves an unique opportunity for the development of an educational resource for future students.

History

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

Details

The monument includes the earthworks and buried remains of the metal ore processing works adjacent to Wood Mine and West Mine on the western side of Windmill Wood on Alderley Edge. The locations of the original Wood Mine and West Mine entrances are included in the protected area as are the modern entrances to each. The works were set up to process copper and lead ores and later to extract cobalt from the copper ores a short time before 1860 by the Alderley Edge Mining Company. The lead works were closed in 1863. Work at the cobalt plant ceased in 1864 and production of copper was abandoned at this site in 1878. Although only operating for a short time, the works processed 168,269 tons of copper ore and produced 3,200 tons of fine copper metal. In addition, almost 100 tons of lead and 11 tons of cobalt-nickel were produced. After 1878 the site stood idle until a new works was constructed, possible in a different location, in 1914. This was sold off in 1926. Among the metal extraction processes on this site, the production of cobalt is of great interest in the history of mining and smelting in England and it is believed that this processing site is unique. The copper ore from the mines was first crushed and then fed into wooden leaching tanks where the copper was removed by dissolution with hydrochloric acid. The resulting liquid was then put into precipitating tanks where scrap iron was added to the acidic mixture causing the iron to be dissolved at the expense of copper which precipitated in a metallic state. The remaining solutions contained iron, manganese, nickel and cobalt. These were treated by being concentrated and then evaporated to produce a cobalt/nickel `speiss'some of which was sold on to manufacturers of paint or enamels. Whilst the production of cobalt at this site is of technological interest, documentary evidence suggests that a ready market for the product was never found. The features of the process which will survive here include the remains of the wooden tanks for acid dissolution and precipitation, the bases of the furnaces for heating the cobalt bearing solutions, the foundations of the cooling tower for evaporating the heated mixture and the beds for the steam engines which powered the entire process. In addition there are the remains of the copper ore crushing machinery, the inclined tramways which brought the ore from Wood Mine and West Mine, the offices and workshops of the processing works and the accommodation for some of the senior artisans on the site. Also on the site, within the monument, there are the remains of the pitheads and shafts of several entrances to the ore-bearing veins in each mine. Notable among these are the foundations for the winding engine houses of Wood Mine and West Mine, the crusher and buddling floors of Wood Mine, and the dressing floors common to the two mines located beside West Mine. The adit entrance shaft for Wood Mine are located in the eastern side of the monument area at SJ85457760 and the possible remains of the winding engine house for West Mine are located on the western side of the site at approximately SJ85267753. The machinery on these sites was finally sold off in 1926 when the mines finally closed. Immediately to the east of the central processing area were four cottages and a well which may have been built for workers in the copper mines and were still in occupation in 1950. At least one of these dated to 1747. Of these only the brick foundations survive and they are included in the scheduling. To the south of the central processing area there were massive hills of waste sand from the copper processing and the remains of the largest sandhill are also included in the scheduling. All fence posts, gates and waymarkers 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
Carlon, C, The Alderley Edge Mines, (1979), 68-71
Carlon, C, The Alderley Edge Mines, (1979), 68-71
Timberlake, S, The Alderley Edge Survey, (1998)

National Grid Reference: SJ 85272 77491

Map

Map
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This copy shows the entry on 19-Nov-2017 at 08:14:22.

End of official listing