A new study published November 5, 2026, found no matching rock source in north-east Scotland for Stonehenge's six-tonne Altar Stone, leaving its origins uncertain.
Scientists have tested the six-tonne Altar Stone at Stonehenge, but a new study published in the Journal of the Geological Society on November 5, 2026, found no matching rock source in north-east Scotland, leaving the stone's ancient journey unresolved.
The Altar Stone is a large slab of Old Red Sandstone, measuring approximately 4.9 metres long and weighing around six tonnes. It lies flat beneath the collapsed remains of the Great Trilithon at Stonehenge on Salisbury Plain in Wiltshire, England, partly hidden by the grass. Stonehenge's construction began around 3000 BC.
For nearly 100 years, the prevailing theory was that the Altar Stone came from west Wales. In August 2024, a study published in Nature pointed towards the Orcadian Basin in northeast Scotland after researchers examined tiny mineral grains, including zircon, apatite and rutile, trapped inside fragments of the stone. The mineral signatures closely matched those found in the region's Old Red Sandstone.
An international team led by geologist Duncan Pirrie examined the Altar Stone in greater detail. The team examined eight fragments held in museum collections and carried out non-invasive measurements on small exposed areas of the monument. Researchers collected around 70 samples from Scottish rock outcrops for laboratory testing.
The scientists looked for a complete combination of geological characteristics, including chrome spinel, clay minerals and barium chemistry. None of the Scottish locations examined had the complete combination of characteristics found in the Altar Stone.
Duncan Pirrie, an emeritus professor at the University of South Wales who led the study, concluded it was "very unlikely" the altar stone had originated from north-east Scotland. He said the stone also definitely did not come from southern Britain. It may have come from somewhere else in Scotland, northern England or perhaps even Ireland.
Nick Pearce, an emeritus professor of geochemistry at Aberystwyth University, said: "We're getting closer. In a geological detective story such as this, ruling out potential source areas is just as important as identifying new ones. Every location eliminated narrows the search and brings us closer to discovering where the altar stone originated. I'm not disappointed. It's part of the process."
Pirrie added: "This is the most comprehensive geological investigation of the altar stone ever undertaken. By combining a wide range of analytical techniques, we have built the clearest picture yet of the stone's composition and tested the leading theories about its origins. So far, none of the locations examined have the same set of characteristics as the altar stone, but the search is not over."
Finding where the stone came from could reveal how far Neolithic communities travelled, how they exchanged resources and how they organised the movement of enormous objects across landscapes. It could also help researchers understand the connections that existed between communities thousands of years ago, long before written records.
Sources
This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.
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