Roseworthy Arsenic Works, 700m west of Cornhill Farm

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.



Despite some damage the Roseworthy Arsenic Works survive well and represents an important survival of the arsenic refining industry. Contemporary photographs together with good documentation enhance the interest of the site. The condensing chambers survive particularly well and the survival of waste dumps is notable.

Details

The monument includes a 19th and early 20th century arsenic works which was operated by the English Arsenic Company between 1897 and 1926. The arsenic works stands in the bottom of a valley formed by an unnamed tributary of the Red River and its associated flue leads up the side of the east facing slope terminating in a substantial chimney. The arsenic works was built during the 1850s and appear on the 1876 edition of the Ordnance Survey map. In 1889 the manager was Captain Josiah Thomas and in 1919, 35 tons of arsenical pyrities and 1,492 tons of arsenic were produced. Arsenic refining ceased in 1926 when the English Arsenic Company abandoned the operation. The structural remains of the arsenic works include a series of eleven stone and brick built conjoined condensing chambers, a shaft calciner in which the arsenic was heated, the truncated remnants of the refining building and a large detached building situated within the northern part of the complex. Leading from the condensing chambers is a stone built underground flue which leads for 250m to a large tapering stone and brick chimney standing on the hillslope above and to the west of the calciner. Waste material from the refining process was dumped to the north where an elongated irregular shaped mound survives. Modern fences and track surfaces are excluded from the scheduling, but the ground below them is included.

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

Legacy

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

Legacy System number:

36047

Legacy System:

RSM

Sources

Other
PRN 26591, Cornwall County Council HES, Cornwall Historic Environment Record,

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