For almost a century archaeologists have been braving the wind and rain on an exposed Welsh hillside in an attempt to solve one of the key mysteries of Stonehenge.

But new research about to be published suggests that over the decades they may have been chipping away at the wrong rocky outcrop on the Preseli Hills in Pembrokeshire.

The work in the hills is a crucial element in the understanding of Stonehenge because it is generally accepted that the bluestones that form part of the ancient Wiltshire monument came from this remote spot in south-west Wales. One of the many huge puzzles remains how the bluestone from Wales travelled 190 miles to the heart of south-west England.

Since the 1920s much of the work in Preseli has focused on a spot known as Carn Meini. Now researchers are claiming that in fact the Stonehenge bluestones actually came from Carn Goedog – almost a mile away.

Richard Bevins, keeper of geology at the National Museum of Wales and one of those involved in the study, suggested he was not going to be terribly popular with some fellow experts.

"I don't expect to be getting Christmas cards from the archaeologists who have been excavating at the wrong place over all these years," he said.

The celebrated geologist Herbert Henry Thomas linked the Stonehenge bluestones with Preseli in 1923 and pinpointed the tor on Carn Meini as the likely source. Over the years teams worked assiduously on the spot searching for evidence of a Stonehenge quarry.

Two years ago there was excitement when a burial chamber was found, leading to speculation that this could be the resting spot of an architect of Stonehenge.

Now, using geochemical techniques, Bevins and his colleagues have compared samples of rock and debris from Stonehenge with data from the Preseli site and concluded the bluestones in fact came from Carn Goedog.

Bevins, who has been studying the geology of Pembrokeshire for over 30 years, said: "I hope that our recent scientific findings will influence the continually debated question of how the bluestones were transported to Salisbury Plain."

There are different theories about how the bluestone may have got to Wiltshire. Some believe it was laboriously transported by man but there is another theory that it could have been swept east by glaciers.

Rob Ixer, of University College London, who also took part in the new research, said: "Almost everything we believed 10 years ago about the bluestones has been shown to be partially or completely incorrect. We are still in the stages of redress and shall continue to research the bluestones for answers."

Bluestones are believed to have arrived at Stonehenge about 4,500 years ago. Some experts believe the bluestones – rather than the much larger sarsen stones that give Stonehenge its familiar shape – were the real draw because they were believed to have healing powers.

The paper setting out the discovery is to be published in the Journal of Archaeological Science.