Researchers have uncovered a secret to Stonehenge's everlasting survival, thanks to a long-lost core taken from the ancient structure. Stonecutter Robert Phillips got his hands on one of the three cores taken from a cracked sarsen stone as metal rods were inserted during restoration work in the 1950s. But it wasn't immediately studied, per the Hill. Rather, Phillips took the sample with him to the US after retirement, and only offered it for study in 2018, two years before his death. "Getting access to the core drilled from Stone 58 was very much the Holy Grail for our research," University of Brighton professor David Nash, a co-author of the study published in PLOS One, says in a statement. He notes that "it would be highly unlikely that we would be able to access this type of material today," given the strict protections that come with the monument's World Heritage Site status.
CT scans, X-rays, and chemical analyses revealed the core, 99.7% quartz, includes tiny grains of quartz cemented together by an interlocking mosaic of quartz crystals. This is what makes the stone "so impervious to crumbling or erosion," per a release. "I've wondered if the builders of Stonehenge could tell something about the stone properties, and not only chose the closest, biggest boulders, but also the ones that were most likely to stand the test of time," Nash says, per Live Science. He also evaluated the so-called Phillip's Core for a 2020 study that found the sarsen stones that make up the monument's central horseshoe came from West Woods, 15 miles north of Stonehenge. A portion of one of the other two cores taken from Stone 58 was found in 2019 at the Salisbury Museum, just 10 miles south of Stonehenge. The other remains missing. (Read more Stonehenge stories.)