Betty Adit tailings works, 170m south west of Harley Farm


Heritage Category: Scheduled Monument

List Entry Number: 1021419

Date first listed: 01-Sep-2009


Ordnance survey map of Betty Adit tailings works, 170m south west of Harley Farm
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This copy shows the entry on 10-Dec-2018 at 21:41:20.


The building or site itself may lie within the boundary of more than one authority.

District: Cornwall (Unitary Authority)

Parish: Camborne

District: Cornwall (Unitary Authority)

Parish: Carn Brea

National Grid Reference: SW 66599 39789


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

Reasons for Designation

For several millennia the western part of the South West Peninsula, namely Cornwall and West Devon, has been one of the major areas of non-ferrous metal mining in England. It is defined here as prospecting, extraction, ore processing and primary smelting/refining, and its more important and prolific products include copper, tin and arsenic, along with a range of other materials which occur in the same ore bodies. Throughout much of the medieval period most of the tin was extracted from streamworks, whilst the other minerals were derived from relatively shallow openworks or shafts. Geographically, Dartmoor was at the peak of its importance in this early period. During the post-medieval period, with the depletion of surface deposits, streamworking gradually gave way to shaft mining as the companion to openworking methods. Whilst mining technology itself altered little, there were major advances in ore processing and smelting technologies. The 18th century saw technological advances turning to the mining operations themselves. During this period, Cornish-mined copper dominated the market, although it was by then sent out of the region for smelting. The development of steam power for pumping, winding and ore processing in the earlier 19th century saw a rapid increase in scale and depth of mine shafts. As the shallower copper-bearing ores became exhausted, so the mid to late 19th century saw the flourish of tin mining operations, resulting in the characteristic West Cornish mining complex of engine houses and associated structures which is so clearly identifiable around the world. Correspondingly, ore processing increased in scale, resulting in extensive dressing floors and mills by late in the 19th century. Technological innovation is especially characteristic of both mining and processing towards the end of the century. In West Cornwall, these innovations relate chiefly to tin production, in East Cornwall and West Devon to copper. Arsenic extraction also evolved rapidly during the 19th century, adding a further range of distinctive processing and refining components at some mines; the South West became the world's main producer in the late 19th century. From the 1860s, the South West mining industries began to decline due to competition with cheaper sources of copper and tin ore from overseas, leading to a major economic collapse and widespread mine closures in the 1880s, although limited ore-extraction and spoil reprocessing continued into the 20th century. A sample of the better preserved sites, illustrating the technological and chronological range, as well as regional variations, of non-ferrous metal mining and processing sites, together with rare individual component features, are considered to merit protection.

Betty Adit tailings works survives well and represents a good example of a 20th century tin reprocessing site. At one time there were many tailings works associated with the Cornish tin industry, but most have been destroyed by later activity. The tailings works at Betty Adit is essentially complete apart from the loss of its machinery and enough remains to be able to read the whole dressing process.


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


The monument includes a 20th century tin tailings works known as Betty Adit or Brea Adit together with an earlier leat and reservoir associated with the nearby Dolcoath Mine. The tailings works is situated on a revetted terrace immediately above and west of the Red River. The site lies within the Cornwall and West Devon Mining Landscape World Heritage Site. The visible remains are mainly associated with the 1920s tailings works and include a series of buddles, frames, settling pits and concrete machine plinths. The Robert Symons' map of 1850 shows a building and the Dolcoath leat in the area. An Ordnance Survey map for 1880 depicts the leat and a reservoir where the building once stood. The 1907 Ordnance Survey map illustrates a radical change in the level of activity within the area, with the appearance of the large primary settling tanks and a series of interconnected leats and channels. The next available Ordnance Survey map dates to 1967-75, shortly after the works were abandoned and shows less detail than is currently known to survive. The visible remains are considered to relate to the period of working between 1928 and 1962 carried out under the name Brea Tin Streams by Ewart Bawden. No trace of the 1880s Dolcoath leat and reservoir are visible on the site; but because the area has seen considerable build up of material they will survive below the later deposits. Tailings works were built downstream of most of the major Cornish mines and were built to reprocess wastes from their larger neighbours. They are essentially independent dressing floors involved solely with the extraction of black tin (cassiterite) from material that had already been processed on at least one occasion. The works rely on water for dressing purposes and the actual processing was carried out using a series of interconnected settling tanks and buddles. At Betty Adit, a complete set of tanks, round frames and buddles of different types survive together with machinery plinths, leats and channels. The raw material entered the works in suspension and flowed into the primary settling tanks in the southern part of the monument. From here it passed through a series of buddles, frames and smaller tanks until by the time it reached the lower northern part of the site much of the tin had been removed.

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


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

Legacy System number: 36048

Legacy System: RSM


Books and journals
Sharpe, A, Brea Adit tailings works, (2006)
Title: Ordnance Survey 1st Edition Source Date: 1880 Author: Publisher: Surveyor:

End of official listing