MADRID, SPAIN—Mónica Alvarez de Buergo of Madrid’s Geosciences Institute and scientists from the University of Calabria collected 50 samples of white marble from the now-submerged luxury villas in the Underwater Archaeological Park of Baia, located near Naples. The Roman emperors Augustus and Nero owned villas in the city, which thrived between the first century B.C. and the third century A.D. “First, thin layers of the collected marble were observed using a petrographic microscope. Then, the mineral composition of the marble was studied using X-ray diffraction and the manganese content was determined with Inductively Coupled Plasma Mass Spectrometry. Scanning Electron Microscopy was then carried out and various isotopes were analyzed,” Alvarez de Buergo said in a press release. The team compared the test results with the chemical signatures of eight of the best marble quarries of the ancient world, and found matches for all but five of the samples. “The variety and quality of the marble identified highlight the importance held by this area in the past seeing as it yielded the best ornamental marble of that time period, and this helps to determine the trade routes that were used at that point in time during the Roman Empire,” she said. For more on marble in Ancient Rome, go to "A Spin through Augustan Rome."