Chips Dating to 1844 Offer New Clues as to Where Stonehenge’s 13,000-Pound Altar Stone Came From
Learn how old museum fragments are helping researchers trace the origins of Stonehenge’s Altar Stone, and why proposed sources in northeast Scotland don’t match.
Museum fragments from the 1844 Altar Stone at Stonehenge are providing new clues about its origins, as researchers struggle to determine where this 13,000-pound sandstone slab came from. Geologists have analyzed museum chips taken from the Altar Stone, which date back to 1844, but its composition does not match any known rock source, including parts of northeast Scotland.
The study, published in the Journal of the Geological Society, narrows the search while leaving the origin unsolved. Co-author Nick Pearce stated, "In a geological detective story such as this, ruling out potential source areas is just as important as identifying new ones." The Altar Stone is a 16-foot slab weighing an estimated 13,000 pounds, part of the bluestones brought from west Wales.
Only three small patches of the stone are visible, making it difficult to analyze. The researchers turned to eight museum chips for insight, finding that its composition is a sandstone with calcite and three distinct ingredients: baryte, a chromium-containing mineral, and a clay that reveals burial depth and heat exposure. Northeast Scotland appears unlikely to be the source, as the chromium mineral is scarce there, and the clay suggests a shallower burial depth than found in Caithness and Orkney.
The study does not propose a new suspect, but the unique composition of the Altar Stone may point to an older or younger rock source than previously considered.
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