Concotto artefacts from the Etruscan settlements of Adria and San Basilio di Ariano nel Polesine

Abstract

The aim of the study is the characterisation of non-vascular ceramic materials from two distinct Etruscan settlements situated in the Po Delta region (north Italy). One excavation took place in 1983 in the village of San Basilio di Ariano nel Polesine (RO), and the other one in 2016 in the small town of Adria (RO). The expectation is to clarify the function of the ceramic materials, in order to better understand the construction process that appears unique for San Basilio, Adria and Spina settlements. These archaeological finds were supposed to be building materials used for covering house walls, as external or internal plasters. Almost all of them present a smooth surface, that goes from red to light grey, and an opposite face that differs in texture as well as in colour. Notable elements are the presence of one or more imprint on the smoothest face, probably due to the impression of thin plant elements, and the presence of some fingerprints on the edges, representing signs of the working process. Furthermore, few pieces are characterised by a twisted decoration pattern. In addition, also several portions of unbaked clay were found in San Basilio site characterized by reeds and branches prints, suggesting the incannucciato technique. Similar materials were found also during the excavation in the shore of Spina (FE). Publications about Spina describe the walls coating as a system of clay slabs, trimmed and painted on a side, with the constant feature of a defined layer of ingobbio. Due to the co-presence of plasters and incannucciato a mixed building technique was suggested: plaster used in the bottom part of the wall being more water-resistant, and raw clay to cover the upper part of the vegetable structure. In this study a set of samples was analysed by means of a multi-analytical approach, i.e. Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), thermogravimetry differential scanning calorimeter (TG-DCS), scanning electron microscopy and energy dispersive spectrometry (SEM-EDS), microscopic analyses on cross sections and valuation of the total porosity. This approach allowed to underline similarities and differences about the composition of the ceramic mixtures and possible coatings, as well as the methodology of firing technique.