Researchers investigating the origins of Stonehenge's six-ton Altar Stone have cast doubt on the theory that it came from north-east Scotland, leaving southern Scotland and northern England among the most promising locations. For decades, experts believed the 16-foot sandstone slab originated in west Wales, but earlier research pointed instead to Scotland. An international team conducted the most detailed geological analysis of the stone to date, examining its structure, minerals, chemistry, and isotopic composition. Published in the Journal of the Geological Society, the findings suggest the stone did not originate in Scotland's Orcadian Basin. Researchers are now focusing on regions containing Old Red Sandstone formations, although some areas of north-east Scotland have not been entirely ruled out.
Lead author Professor Duncan Pirrie explained that the Altar Stone's distinctive calcite cement and baryte mineral content could help scientists identify its source. Unlike Stonehenge's larger, relatively local sarsen stones and smaller bluestones traced to Wales, the Altar Stone remains unmatched to a specific geological location. Researchers believe determining its origin could reveal more about the engineering and organizational abilities of Neolithic people, who transported massive stones over considerable distances during the construction of Stonehenge. Separately, Stonehenge curator Win Scutt suggested that transporting the monument's enormous sarsen stones may have involved competition among work groups, potentially turning the challenging task into a form of prehistoric sport.