PrehistoryNeolithic · Stonehenge, Wiltshire, United Kingdom
Stonehenge's Altar Stone probably did not come from north-east Scotland, new geological study finds
The most detailed analysis yet of the six-tonne sandstone slab rules out the Orcadian Basin locations tested so far, leaving its source an open question.
In brief 3 key points
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- A new study in the Journal of the Geological Society examined the Altar Stone's structure, minerals, chemistry and isotopes
- About 70 samples from north-east Scotland did not match the stone
- The source may lie elsewhere in Scotland, in northern England or perhaps in Ireland
The search for the source of Stonehenge's Altar Stone has moved on after geologists found that it is very unlikely to have come from north-east Scotland, the area proposed in 2024. The results were published in the Journal of the Geological Society.
The study was led by Duncan Pirrie, an emeritus professor at the University of South Wales, with researchers including Richard Bevins and Nick Pearce of Aberystwyth University.
A six-tonne puzzle
The Altar Stone is a 4.9-metre sandstone slab weighing about six tonnes. It lies flat beneath the collapsed upright and lintel of the Great Trilithon. For about a century it was thought to come from west Wales, until research in 2024 pointed to the Orcadian Basin in north-east Scotland, more than 400 miles from Stonehenge.
The team combined new non-invasive observations of the stone in place with study of eight fragments held in museums. They examined its structure, minerals, chemical composition and isotopes to build a detailed fingerprint.
Seventy samples, no match
Members of the team then collected about 70 rock samples in north-east Scotland and tested them in the laboratory. None of the locations examined so far has the same set of characteristics as the Altar Stone.
“So far, none of the locations examined have the same set of characteristics as the Altar Stone.”
Duncan Pirrie, University of South Wales
Pirrie said the stone definitely did not come from southern Britain. It may have come from elsewhere in Scotland, from northern England or perhaps even from Ireland.
“Ruling out potential source areas is just as important as identifying new ones.”
Nick Pearce, Aberystwyth University
Bevins said the study identifies the specific geological features to look for, so that future fieldwork can be targeted more effectively.
Sources (3)
Peer-reviewed paperfrom University of South Wales and Aberystwyth University
- Mystery origin of iconic Stonehenge Altar Stone deepens as search narrows (Phys.org)
- Origin of Stonehenge’s altar remains enigma as north-east Scotland theory ruled out (The Guardian: archaeology)
- Search for the source of Stonehenge's Altar Stone rules out north-east Scotland (Journal of the Geological Society)
Paper: Pirrie et al., Journal of the Geological Society (2026), doi:10.1144/jgs2026-090
Edited by Guiseppe Weijermars
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