Pirrie said his latest publication on the Altar Stone has “built the clearest picture yet” and was “the most comprehensive geological investigation of the Altar Stone ever undertaken”.
Professor Nick Pearce from Aberystwyth University, who worked on the previous research, said “ruling out potential source areas is just as important as identifying new ones”.
The geochemistry expert said: “Every location eliminated narrows the search and brings us closer to discovering where the Altar Stone originated.
“The 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.”
The world-famous Wiltshire monument was constructed in multiple phases over thousands of years, between 3000 and 1600 BC. However, not all stones come from the area.
The smaller bluestones travelled around 225km from west Wales with research suggesting a few were taken directly from another circle.