Material sources of the Roman brick-making industry in the I and II century A.D. from Regio IX, Regio XI and Alpes Cottiae

Abstract

Bricks, fine pottery, ceramic gears and tiles are among the human-made objects routinely recovered in archaeological documentation. Sites associated with early civilizations can provide thousands of samples from a single excavation. They come in endless varieties according to economic and social circumstances and, as debris can last almost forever, provide important clues about the past behaviours in human societies. Any information about the provenance of ceramics is highly valuable in archaeological analysis. In the case of Roman brick-making, the provenance and manufacture of clayey materials are usually interpreted only by studying stamps imprinted on the artefacts, when available. In this paper, the making of bricks, tiles and other ceramics for building purposes is investigated, in relation to the possible sources of raw materials used for the industry. The major questions to be solved relate to the sites from where the Romans collected the raw materials, the technologies they applied to make bricks and other clayey building materials, and how far have they transported raw resources and final products - i.e. mainly bricks and tiles - after furnace treatments, considering that a crucial point was the nearby availability of timber, water, and sandy soils without stones. Some achievements to classify artefacts with identical provenance have been obtained, using the structural transformations induced in the material by thermal treatments of pottery. Comparisons have been made of the trace elements chemical composition in ICP-MS and some physical properties, including magnetic, VSM hysteresis loops, and mineralogical features with XRD and IR analysis, have been identified as proxies to elucidate the possible provenance of rough materials, and appreciate the technologies used by the Roman brick-making industry.