Boulby Alum Quarries and works


Heritage Category:
Scheduled Monument
List Entry Number:
Date first listed:


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

Redcar and Cleveland (Unitary Authority)
National Park:
National Grid Reference:
NZ 75374 19432

Reasons for Designation

Alum is a chemical used principally in the textile industry for fixing dyes. It is not found in a natural state in Britain but can be manufactured from some types of shale. During the medieval period in Britain alum was imported, mostly from Italy. Domestic production began in the north of England in the early 17th century. The industry flourished in the north for 200 years until the mid-19th century when it was overtaken by new techniques using shale from coal mining, whilst after 1880 aluminium sulphate replaced alum for most industrial purposes. The last English aluminium works (at Goole) closed in 1950. Approximately 50 alum sites have been identified in England. Most were along the Cleveland and Yorkshire coast. Other early sites are known on the south coast, particularly in Dorset and Hampshire. Alum works comprise two main monument types: the quarry where extraction and initial processing took place, and the alum house where final processing took place. Alum shale was extracted from quarries sited on steep inland hillsides or coastal cliffs. Initial processing on the quarry floor consisted of calcination by burning shale in clamps, and the production in settling pits of alum liquor. The liquor was transported to processing works in sealed casks or through wooden channels known as liquor troughs. Larger quarries possessed inclines and haulage gear and sometimes harbour facilities. Stores, workshops and laboratories can also survive. Evidence of secondary industries such as epsom salts and iron silicates production is also preserved at alum works. The alum industry was the first chemical industry in Britain. Its quarries and works illustrate the early stages of the industry and the technological advances through the period known as the Industrial Revolution. The alum industry also offers important information about wider changes in social and economic conditions during this period. The large scale of the industry's workings also mean that its remains are today a major component of coastal landscapes. A sample of the better preserved sites, illustrating the regional, chronological and technological range of this class of monument, is considered to merit protection.

The alum quarries and associated works at Boulby survive well and significant remains of the technological processes are preserved. The Boulby quarry is one of the best national examples of a technically advanced alum quarrying complex. As a multi-period site the monument demonstrates the advances in technology and innovation over the years. The monument has a wider landscape importance as the nearby hamlet of Boulby was built almost exclusivly for the alum workers. Thus the site is also important for the study of social and domestic conditions.


The monument includes remains of the Boulby Alum Quarries and associated features, which lie on north facing coastal cliffs 1.5km north of Easington. The monument includes quarries, the remains of structures used for initial processing and transport of the alum on the quarry floor and an ironstone mine. The monument extends for about 1km along the coastline and the quarry face is up to 200m inland from the current cliff edge. The workings originally extended further north, but substantial areas have been lost to coastal erosion. The Boulby alum works was one of the most productive and long lived in the region. They were started in the 1650s by the Conyers family of Boulby Manor and soon after control passed to the Baker-Baker family. Despite fluctuations in the price of alum in the 18th century the works thrived and in 1784 expanded westward with the opening of the New Works. Technological improvements led to further increases in production and the halving of the workforce. However, advances in the alum industry elsewhere were having a serious effect on the industry in the region, making the use of massive calcining clamps at Boulby uneconomic. The sale of by-products such as Epsom salts and slam (a material used in glass manufacture) prolonged its life until the closure of the works in 1871. The alum was extracted from a seam of alum shale up to 60m thick which lay beneath a capping of sandstone. This overburden of stone was removed and much was used for building stone. There are two discrete areas of quarrying, the earliest being at the east end at Rockhole Hill where a large quarry scoop with three terraces survives. These are the remains of a stepped quarry face. The quarry waste generated was dumped on the land to the east where a series of spoil heaps still survive. To the west of Rockhole is the second area of quarrying known as New Works. This is separated from Rockhole by two large flat topped spoil tips formed from dumping waste material from New Works into the old quarry area to the east. The New Works consist of a long scree slope that descends from the back of the quarry from which massive boulders have fallen. Beyond this is a complicated series of terraces, quarry scoops and dumps that cut and re-cut each other through several phases. The sequence of quarrying became more complicated as the mining progressed westward and material was dumped to the east where it appears to have been modified or re-used in later periods of activity. At the west end, large stone revetment walls were built partly to support the sides of the quarry scoops whilst processing took place within the quarry floor and also to store burnt shale. The first stage of processing was calcination, which occurred in large clamps. Remains of these survive as large mounds of shale known as calcination bases, some of which were vented from below by stone tunnels which still survive. The next stage was steeping which occurred in stone lined pits. There were a total of 17 steeping pits in the New Works, but only fragments now survive protruding from the cliff edge, the remainder having been lost to coastal collapse. Remains of further steeping pits survive along the level area at the north edge of the Rockhole quarry. Excavations in the 1960s found several structures including three roomed buildings at Rockhole and at New Works, which are still exposed. These buildings are thought to be laboratories or a blacksmith's workshop. Extending west to east are the partial remains of a stone culvert which supported a wooden channel known as a liqour trough. This carried alum from the steeping pits to the alum house located to the east of the monument. Some cisterns, reservoirs, tunnels and further buildings, including a mess hut, also survive as visible structures. Remains of other structures such as culverts, workshops, offices and stores are also thought to survive below ground level throughout the monument. In the south east of the New Works is the remains of an ironstone drift mine tunnelled into the base of the quarry face.

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:
Legacy System:


Books and journals
Blood, K, Boulby Alum Mine, (1993), 12
Blood, K, Boulby Alum Mine, (1993), 1-20
Chapman, K, 'Cleveland Industrial Archaeologist' in Exavations at Boulby Alum Works, , Vol. 2, (1975), 27-34


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 Digital, Culture, Media and Sport.

End of official listing

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