concluded<\/a> it came from the Orcadian Basin of northeastern Scotland, a journey of some 700 km or more.<\/p>\nAccording to Professor Pirrie and co-authors, the picture is far less settled.<\/p>\n
They do not dispute the earlier dating work, which points to a Laurentian origin, meaning ancient crust associated with the Scottish Highlands, for the heavy minerals in the stone. But age data alone, they argue, are not enough.<\/p>\n
\u201cThis is the most comprehensive geological investigation of the Altar Stone ever undertaken,\u201d Professor Pirrie said.<\/p>\n
\u201cBy combining a wide range of analytical techniques, we have built the clearest picture yet of the stone\u2019s composition and tested the leading theories about its origins.\u201d<\/p>\n
\u201cSo far, none of the locations examined have the same set of characteristics as the Altar Stone.\u201d<\/p>\n
\u201cThat tells us the search is not over, but we are now far better equipped to focus on the areas most likely to yield an answer.\u201d<\/p>\n
Because the Altar Stone itself cannot be sampled, the researchers worked from eight museum fragments confidently linked to it, along with portable X-ray measurements of the three small patches of the stone that are exposed at Stonehenge.<\/p>\n
The stone contains a distinctive scatter of baryte, a barium mineral that cements the sandstone\u2019s grains, which gives the stone unusually high barium readings.<\/p>\n
It also holds chrome spinel, a heavy mineral that is scarce in Old Red Sandstone from much of the Orcadian Basin, including Orkney, Caithness, the Moray Firth and Shetland.<\/p>\n
The stone\u2019s mixed-layer illite\/smectite clay has about 20% expandable layers, a sign it has not been deeply buried or heated. Rocks in Caithness and Orkney show values below 10%, which would exclude those areas.<\/p>\n
The stone also contains tosudite, a rare clay mineral, and shows no sign of the low-grade metamorphism found in the Southern Uplands of Scotland, which rules the region out.<\/p>\n
The stone\u2019s ripple-laminated structure is consistent with deposition by flowing water, and that its calcite cement formed during burial rather than near the surface.<\/p>\n
Other candidates, West Wales and the wider Anglo-Welsh Basin, were excluded earlier.<\/p>\n
The Midland Valley of Scotland is ruled out by its abundance of rock fragments.<\/p>\n
Carboniferous sandstones from southern and central Britain are a poorer isotopic match than the Old Red Sandstone, although the Old Red Sandstone\u2019s isotope record is incomplete because strontium data are missing.<\/p>\n
\u201cFor almost a century, the prevailing view was that the Altar Stone came from west Wales,\u201d said Aberystwyth University\u2019s Professor Richard Bevins.<\/p>\n
\u201cOur previous research overturned that assumption and pointed instead to Scotland as the most likely source.\u201d<\/p>\n
\u201cThis latest study significantly refines the search by identifying the specific geological characteristics we need to look for, allowing future investigations to be targeted more effectively.\u201d<\/p>\n
\u201cWith each new piece of evidence, we move closer to solving one of Stonehenge\u2019s most enduring mysteries.\u201d<\/p>\n
\u201cIn a geological detective story such as this, ruling out potential source areas is just as important as identifying new ones,\u201d added Professor Nick Pearce, also from Aberystwyth University.<\/p>\n
\u201cEvery location eliminated narrows the search and brings us closer to discovering where the Altar Stone originated.\u201d<\/p>\n
\u201cThe stone is unique among those at Stonehenge, and tracing its source would provide valuable new insights into its remarkable journey to Salisbury Plain thousands of years ago.\u201d<\/p>\n
The study<\/a> was published today in the Journal of the Geological Society.<\/p>\n_____<\/p>\n
Duncan Pirrie et al. 2026. Searching for the origin of the Stonehenge Altar Stone: new sedimentological, petrographical, mineralogical, geochemical and isotopic constraints. Journal of the Geological Society 183; doi: 10.1144\/jgs2026-090<\/p>\n","protected":false},"excerpt":{"rendered":"A new analysis by University of South Wales Professor Duncan Pirrie and his colleagues undercuts the leading theory…\n","protected":false},"author":2,"featured_media":676271,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[286418,286419,286420,5040,61,286421,60,128153,63708,286422,82,9036,286423,286424,209350,286425,303],"class_list":["post-676270","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-altar-stone","tag-barium","tag-baryte","tag-england","tag-ie","tag-illite","tag-ireland","tag-mineral","tag-paleolithic","tag-sandstone","tag-science","tag-scotland","tag-smectite","tag-spinel","tag-stonehenge","tag-tosudite","tag-united-kingdom"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/676270","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=676270"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/676270\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/676271"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=676270"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=676270"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=676270"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"The](\"https:\/\/cdn.sci.news\/images\/enlarge14\/image_15179e-Stonehenge-Altar-Stone.jpg\")
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