CONTEXT 185 : SEPTEMBER 2025 35 ROOFING West Highland Slate is the most famous of the Scottish slates, used internationally. The West Highland Slate islands of Seil, Easdale, Belnahua and Luing are known as ‘the islands that roofed the world’ for their history of global export. In all, West Highland Slate was produced from at least 64 separate quarries in Argyllshire and Inverness-shire, mainly centred around the villages of Ballachulish, Easdale, Cullipool and Tayvallich2. It is the darkest Scottish slate, typically dark grey to dark blue-black, and displays a distinctive crenulation (rippling) on the surface. Small iron pyrite (‘fool’s gold’) cubes up to 1 cm in size are common. Highland Border Slate was worked at around 80 or so quarries, all located within a narrow swathe of ground that extends from the Isle of Bute up to Dunkeld in Perthshire, along the boundary of the highlands. Although not as widely exported as West Highland Slate, Highland Border Slate was a regionally significant roofing material. Ranging in colour from reddish/purplish grey to grey and greenish grey, it can appear striped across the face of the slate if the original bedding of the rock is oblique to the cleavage. This gives rise to the particularly distinctive ‘tartan’ slates of Aberfoyle, which are striped in alternating red and green. Macduff Slate was sourced from a few hundred, often comparatively small quarries clustered around the Hills of Kirkney and Tillymorgan (the ‘slate hills’) in Aberdeenshire and some other quarries in Banffshire, and it is a significant traditional roofing material in this corner of Scotland. Macduff Slate is typically grey in colour and has a slightly rough but generally flat, non-rippled surface. The current Scottish slate market The only way to obtain genuine Scottish slate for roof repairs today is by reclaiming slates from older buildings when they are re-roofed or demolished. This finite resource is rapidly dwindling. Slates from England and Wales can be used for replacement in some cases but are rarely a satisfactory match. Instead, the vast majority of slate used nowadays in Scotland is imported from outside the UK, most significantly from Spain. This not only threatens the character of many culturally significant buildings and areas, but also results in around £120 million per year exiting the UK’s economy. If this instead went to local quarrying enterprises, it would create and sustain muchneeded skilled jobs in rural areas. Furthermore, over the last decade, the price of imported slate has increased at more than twice the rate of inflation. The inability to meet demand with our own roofing slate therefore leaves Scotland, and the UK as a whole, increasingly vulnerable to erratic and rapidly increasing import prices, with limited alternatives. Prospects for the industry The good news is that slate quarrying in Scotland did not cease due to a lack of available material. There are plenty of geologically suitable sources for roofing slate with the potential to be redeveloped today. All three Scottish slate types are historically significant and unique, and may have potential to become the focus of feasible modern enterprises, filling a significant gap in the current market for roofing materials. A recent report published by British Geological Survey (BGS), funded by HES, found that 32 historic sources of Scottish roofing slate still have ‘development potential’, based on the historic significance of the stone and other factors, such as quarry accessibility and local environmental protections. Cullipool, Isle of Luing One of the sources of slate with development potential is at Cullipool on the Isle of Luing. Situated just north of the conservation village of Cullipool lie six disused West Highland Slate quarries, the last of which was worked until 1965. The slate resource at these quarries remains relatively well exposed and is not situated in statutorily protected land. The resumption of quarrying activity at Cullipool also has the potential to directly address two pressing issues the islanders currently face: population decline and coastal erosion. At its height, the slate quarrying industry on Luing employed 170 men and sustained a thriving island population of 600 people. Today, the population of Cullipool is approximately West Highland Slate from Easdale, showing common cubes of pyrite and a strong crenulation (‘grain’) on the surface (Photo: British Geological Survey, UKRI) 2The Building Stone Database for Scotland. Available at webservices.bgs.ac.uk/ buildingstone
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