Trinity research on Valentia Slate results in its designation as a Heritage Stone


The natural stone, which only occurs in Co. Kerry and which has been used since at least 1816, has recently been awarded the Status of “International Union of Geological Sciences Heritage Stone”. This coveted status is only awarded to stones with a long history of significant use and which are still available for conservation purposes

Valentia Slate has been used in many landmark buildings internationally, including the floors and roofs of the House of Commons in London, and in 2022 was used to reroof the Rubrics in Trinity.

Valentia Slate now joins Connemara Marble as the only Irish stone types currently with this designation (of which there are 55 globally).

The Rubrics roof, closely showing the Valentia slate.

Research by the Trinity research group STONEBUILT Ireland, based in Geology in the School of Natural Sciences and led by Professor Patrick Wyse Jackson and Dr Louise Caulfield, in collaboration with colleagues at Valentia Slate Company Ltd and Carrig Conservation Consultants, has resulted in this global designation.

The work has just been published in the Irish Journal of Earth Sciences and can be read open access on the journal website.

Valentia Slate has all of the qualities needed for excellence in construction and domestic use. It is extracted underground on Valentia Island in the same facility that was opened by Peter Fitzgerald, the Knight of Kerry, in 1816. The company operates a zero-waste policy in extracting slate for a wide variety of purposes including flooring, roofing slates, kitchen countertops and funerary headstones.

The opening of the Valentia Slate quarry.

Worldwide, buildings are major emitters of greenhouse gases. Natural stone is a very low-carbon building material and Valentia Slate is delighted to be part of a modern trend to use more natural stone and timber in architecture, simply because this approach is better for the climate.

Professor Patrick Wyse Jackson said: “Valentia Slate is a unique stone type that only occurs in Co. Kerry. Its characteristics allowed it to be split into roofing slates but also large slabs and it was utilised for a wide variety of domestic and commercial applications. Amongst the more unusual uses were for headstones, garden benches, billiard tables, water tanks, and walling for bonded warehouses. The research project STONEBUILT Ireland, funded by the Geological Survey Ireland and Office of Public Works, enabled research on this important sustainable commodity.”

A beautiful, ornately carved bench made from Valentia Slate, now at Tralee Library.

Aidan Forde, a geologist, is owner of Valentia Slate Company Ltd. He said: “This recognition is also of the expert and hard-working staff of Valentia Slate who have made the company what it is today. This award is recognition, not only of their own efforts in keeping Valentia Slate available for use in sustainable construction, but also the work of the many generations of South Kerry people who worked at the quarry.”

Peter Cox, a material scientist, is founder and managing director of Carrig Conservation International Limited and has decades of experience in the Conservation of historic Buildings across the world. He commented: “Valentia Slate is one of the purest and finest products I have come across in my forty years working in this sector. The material has been used on many very important international buildings; it is vitally important that historic materials such as Valentia Slate are available for conservation and repair of these buildings. It is an added bonus that slate is now available from an Irish source to reduce carbon in our modern construction market.”


Source: Trinity College Dublin

Autor: Thomas Deane

Photo: Prof. Patrick Wyse Jackson.

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