Earth Science in the Knowledge and conservation of the materials culture

There are different sources that give us the possibility to study the history of the human kind: written texts, traditions, the finds of the excavations like bones, pottery, the building structures. Particularly the study of the building finds like, bricks, building mortars, plasters show to be interesting because these finds still preserve not only the shape but the constitutive material realised by the ancient masons. The more the data we are able to get from these finds, the more we can contribute to the knowledge of our past but nevertheless we can acquire information useful to the conservation of our Cultural Heritage. Some methods of study are often inherited from the typological archaeology (styles, cronotypologies), from the archaeological excavations (stratigraphic analysis of the layers) and/or from the archaeometry. Relevant characterizations come from chemical, mineralogical and petrographical analyses. For example, considering the mortars, the observation of the aggregate tell us if a sand was utilised better than a crushed stone and if this aggregate was sieved. Moreover its mineralogical composition gives information on the supply zones. The study of the binder gives information on the stone utilised to produce the lime, on the technology utilised in the burning and slaking phases (presence of lumps, charcoal etc.), on the presence of additives. As regards to bricks and pottery, it is possible to go back to the original raw material, to recognise possible mixtures of different clays, to reconstruct the production technologies such as the firing conditions (temperature, atmosphere). As regards to the stone materials it’s possible to identify their provenance to determinate the conditions of conservations, to investigate the past conservation treatments and the microstructural variations determined by working and weathering. This information can help in setting the more suitable conservation interventions. On the whole the crossed use of archaeological and archaeometric data compared with the written and iconographic sources, allows to reconstruct the physical history of a building and to reveal “the rules of the art”, often real secrets, but also the loss of knowledge, the lack of care in the working of our ancestors. For these reason the Earth Sciences can give voice to objects that otherwise would stay silent, it’s the way “the Materials Culture” can speak to us.