Constraining the provenance of the Stonehenge ‘Altar Stone’: Evidence from automated mineralogy and U–Pb zircon age dating

New evidence challenges the long-held assumption that Stonehenge's Altar Stone originated from Milford Haven, west Wales. Using automated mineralogy and U-Pb zircon age dating, researchers found distinct mineralogical and geochemical signatures in the Altar Stone that differ significantly from those of the Cosheston Subgroup sandstones at Mill Bay. The presence of abundant kaolinite in the Altar Stone suggests a source further east, near the Wales-England border, undermining the hypothesis of a sea-based transport route for the bluestones. This study supports a land-based route for the Altar Stone, possibly via a natural corridor from west Wales to the Severn estuary, aligning with recent strontium isotope evidence indicating connectivity between these regions during Stonehenge's early construction phase around 3000 BC.

Bevins, R. E., Pirrie, D., Ixer, R. A., O’Brien, H., Pearson, M. P., Power, M. R., & Shail, R. K. (2020). Constraining the provenance of the Stonehenge ‘Altar Stone’: Evidence from automated mineralogy and U–Pb zircon age dating. Journal of Archaeological Science, 120, 105188. https://doi.org/10.1016/j.jas.2020.105188