order to compare the samples, the team selected some of the most well-known and widely-used white marble from the Roman period in the Mediterranean basin. Specifically, they selected eight varieties from the best marble quarries in Italy, Greece and Turkey.
Differences owing to the crystal, the manganese and the isotopes
The data reveal that the parameters that have contributed the most to identifying the material and its origin have been the petrographic microscopy -more specifically, varying crystal sizes depending on the source of the marble-, the manganese content (whose content can vary between 0.84 parts per million and 1093.8 parts per million) and the difference in oxygen and carbon isotopes.
The results, which are published by the journal 'Applied Surface Science', demonstrate that these variables have made it possible to confirm that the marble analysed came from different quarries: Carrara in Italy; Proconnesos, Docimium and Aphrodisias in Turkey; and Thassos, Paros and Pentelicon in Greece. The origins of just five of the fifty samples could not be confirmed.
"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", points out Alvarez de Buergo, "and this helps to determine the trade routes that were used at that point in time during the Roman Empire".
"When working with built cultural heritage, it is important to know where the marble originated so that its deterioration compared to reference materials can be determined. That way, we can test whether treatments need to be applied, as well as identify which materials to use in the event that the original material needs to be replaced", indicates the researcher, who emphasises the importance of scientific techniques in finding out more about our past.
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Michela Ricca, Cristina Maria Belfiore, Silvestro Antonio Ruffolo, Donatella Barca, Monica Álvarez De Buergo, Gino Mirocle Crisci, Mauro Francesco La Russa. "Multi-analytical approach applied to the provenance study of marbles used as covering slabs in the archaeological submerged site of Baia (Naples, Italy): The case of the Villa con ingresso a protiro". Applied Surface Science 357 (Part B): 1369–1379, December 2015.