The source of marble for a statue of Apollo on the Greek island of Delos has been a mystery to art historians and archaeologists for decades. The stone's chemistry pointed geochemists to the southern end of the nearby island of Naxos, but no one thought there were ancient marble quarries there. A geoarchaeologist believes he found the source.
source https://phys.org/news/2021-10-tucked-away-marble-quarries-source-archaic.html