Mithras in Tróia (Portugal): an art historical and archaeometric analysis of the roman marble bas-relief with the Banquet of the Gods Mithras and Helios

Abstract

In the early 1930s, archaeologist Marques da Costa reported the finding of a fragmentary marble bas-relief depicting the banquet of the gods Mithras and Helios in Tróia, where a Roman industrial settlement producing fish-salting goods evolved since the 1st century CE. Tróia is located on a sandy peninsula on the left bank of the river Sado on the southwestern Atlantic coast of Portugal. Archaeometric analyses were carried out to determine the origin of the marble. A multi-method approach was applied to combine polarisedlight microscopy, cathodoluminescence, X-ray powder diffraction, and stable C and O isotope analysis in order to determine the marble features. After their checking with the available analytical data-base, they perfectly match with the most important regional marble, the Lusitanian Estremoz Anticline (Portugal). The article aims to present the art historical study of the mithraic bas-relief and to contribute to a better understanding of how the identification of the marble can clarify and support questions about the workshop that would have produced the piece.