A multi-analytical study of architectural fragments from the Marzamemi II “Church Wreck”

A minero-petrographic and physico-chemical investigation was carried out on several archaeological samples of green architectural stone material from the Marzamemi II site (Sicily). The samples belonged to a Byzantine wreck sunk off the cost of Marzamemi, also known as “Church Wreck”. In addition, geological samples from Larisa quarries in Thessaly, Greece, were analysed, with the aim of identifying the area of origin of the geo-materials selected for the realization of the architectural decorations. Optical Microscopy (OM), Scanning Electron Microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), X-Ray Powder Diffraction (XRPD), and Raman spectroscopy permitted to define the material as Green Thessalian stone, named also as verde antico or lapis atracius in the recent times. From a mineralogical point of view, the samples can be defined as ophicarbonate breccia composed of inhomogeneous material that consists of mixtures of serpentine minerals and calcite. Accessory minerals such as magnetite and chromite were also present both in archaeological and quarry samples. The archaeological samples were also studied to define their state of conservation and their degree of degradation caused by their stay underwater for several centuries. Physical characterization of porosity was obtained by Nuclear Magnetic Resonance (NMR) to set the ground for the future conservation procedures. Indeed, only a wide characterization which consider the material degradation, the material composition and the microclimate is fundamental to address the conservation of such important remains.