The white colour in Etruscan polychromes on terracotta: Spectroscopic identification of kaolin

The present work reports on a spectroscopic study of white colour samples collected from Etruscan polychromes on terracotta from the Cerveteri area. In particular, both white-on-red potsherds of the Orientalising period and high-value polychromes of the Archaic period were considered. The white pigment, a fundamental element in this class of artworks, was not clearly identified in previous archaeological and analytical studies, although the use of kaolin was tentatively proposed. Therefore, samples from the Monte Sughereto kaolin quarry in the Cerveteri area were also studied. The results of detailed analyses carried out using micro-Raman spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy first show that the quarry material is a high-purity kaolin containing quartz. Raman results strongly suggest that the same kind of kaolin was employed in the polychromes of the Archaic period. As to white-on red potsherds, infrared results have a key role in showing that the white pigment is a kaolin closely corresponding to the quarry material since a particular kaolin polytype (dickite) is dominant in both cases. The present work thus provides the first definitive identification of the white pigment used in Etruscan polychromes on terracotta from the Cerveteri area, and suggests that the source of kaolin might be the Monte Sughereto quarry.     

Different methods for soluble salt removal tested on late-Roman cooking ware from a submarine excavation at the island of Pantelleria (Sicily,Italy)

This paper deals with the comparative evaluation of different procedures of salt extraction designed for archaeological ceramics from submarine burial environments. The experimental work was carried out on a particular type of late-Roman cooking ware finds (Pantellerian ware) found in a shipwreck near the shoreline of the Island of Pantelleria (Sicily). The studied ceramic test-pieces were first recognised in terms of bulk characteristics (mineralogy, petrography and chemistry). SEM-EDS observation allowed verification of the presence of various secondary minerals at the surface and in the pore spaces formed after the prolonged permanence in seawater under oxidising or reducing conditions. Pore-size distribution was also determined in the same fragments that had been subjected to the salt extraction routines. Three salt extraction methods were tested: two methods based on diffusion processes (water immersion under stationary conditions and under mechanical stirring conditions) and one method based on both diffusive and advective processes (multiple packages of sepiolite). The obtained experimental data allowed us to identify strengths and weaknesses of the tested procedures with practical spin-off for archaeologists and restorers (efficiency, kinetics, compatibility with the ceramic substrate, costs and simplicity of use). Salt extraction under mechanical stirring was the most effective method and, for this reason, is suitable for laboratory fieldwork during or immediately after submarine archaeological excavations. Similar advantages are also intended for the preliminary treatments of the most precious findings prior to museum storage.     

The contribution of urban-scale environmental monitoring to materials diagnostics: A study on the Cathedral of Modena (Italy)

The problem of environmental monitoring aimed at identifying and evaluating the weathering mechanisms affecting historical stoneworks is here discussed and a methodology based on the use of already available, long record, urban-scale environmental data is proposed. An example of its application to the Cathedral of Modena (Italy, XII-XIV century, included in the UNESCO's World Heritage List) is then presented. In this case, the methodology allowed the identification of the main degradation causes, which found significant confirmation by material diagnostics on the available samples and finite element structural modelling. Thanks to the decay causes identification allowed by the proposed methodology, more effective restoration procedures can be outlined.     

New concepts in reassessing mining heritage: A study and its implications from the Ancient Iron Mine of Llumeres (North Spain)

The possibility of giving a continuing value to an abandoned historic mine is not only of academic interest but can be a crucial economic and heritage issue for regions with long mining traditions but which are now severely affected by mine closures. This article suggests a different perspective on the rationale for studying, preserving and developing our mining heritage as an educational facility. To illustrate the case, the ancient iron mine of Llumeres, in the Asturias region, in North Spain, is presented as an example. A key point of our thesis is that a closed mine is not a ‘dead entity’ but simply in transition to another useful state and that after the closure, another organism arises, with very different appearance and vital signs. We suggest that this new organism be recognised for its high patrimonial value and that this heritage value be preserved. Accepting this point of view would mean an increase in efforts to identify and appropriately manage these vital signs. We propose that the particular mining-related aspects (which are usually viewed as negative, such as subsidence or groundwater modification), be considered as part of the heritage of the mining activity, considered in the widest sense. To facilitate understanding, these are discussed in comparison to those for a prehistoric cave, for which there is a broader experience and solid knowledge and recognition of heritage value. We have also analyzed the importance of recognising the geometric and functional relationships between the underground workings and the superficial signatures, in defining an extended patrimonial entity, which has been recently presented to the cultural and political authorities. For the case of the iron mine of Llumeres, we explain the methodology required to analyze and classify the documents in order to investigate and reconstruct the 3D geometric structure of the mine and how this can be integrated into a Geographical Information System (GIS) to improve management and editing of the information. Additionally, the historic mining technological methods employed in the underground workings of Llumeres have been studied and all the information integrated into a 3D visualization package and made available as a free 3D video sample of the subsurface information. In summary, this work represents a major step forward in improving our knowledge of the ancient iron mine of Llumeres and, as a consequence, it has been possible, for the first time, to consider the underground mining heritage in the framework of the better known (but as yet unrecognised) overground heritage. This new patrimonial entity offers enhanced possibilities for acceptance and recognition in a societal context and to aid that acceptance, we propose a radical conceptual change of perspective, pointing out new elements requiring research.     

A Mössbauer study of some coloured marbles (cipollino mandolato, rosso antico and fior di pesco): implications on the nature of their colour

⁵⁷Fe Mössbauer spectroscopy permits an explanation of the formation of the iron-bearing species present in three types of coloured marbles, known as cipollino mandolato, rosso antico and fior di pesco. Structural Fe²⁺ and Fe³⁺ located in silicates, together with the remains of weakly ferromagnetic hematite, arise from primary sediments. Fe²⁺ located in carbonates and anti-ferromagnetic hematite are formed by redox processes during marble formation. The relative contents of the iron species in the three types of marbles depend on the composition of the primary sediments and on local conditions during metamorphism. Knowledge of the type and amount of the iron species in marbles may help in the reconstruction of the redox processes, which took place during marble formation. The deviations of the Morin transition of the hematites play the role of genetic indicator because purity, crystallinity and the red hues of hematites in marbles can be related to the environment of formation.     

The building stones of the ancient centre of Naples (Italy): Piperno from Campi Flegrei. A contribution to the knowledge of a long-time-used stone

Piperno, a Late Quaternary magmatic rock cropping out on the eastern side of the Campi Flegrei (Italy), is probably the most important building stone of Naples, used over a time-span from at least the Roman age until the beginning of the 20th century. Despite its wide diffusion in the monumental architecture of Naples, very little is known about this rock, as regards its technical features, as well as the geological aspects. This paper aims at providing a first overall contribution towards a rediscovery of this long-time-used material, in view of careful restoration works, which nowadays at Naples only take into account the proper geological features of the stone in a few peculiar cases. Thus, it seems of extreme importance to understand the basic parameters of Piperno and, above all, its response to weathering agents. Main mineralogical, petrographical and engineering–geological properties are presented here for the first time, with specific reference to two sampling areas, located at Pianura and Soccavo, in the western sector of the Neapolitan urban area. As far as many of its physico–mechanical features are concerned, Piperno extends over a wide range of values, which allow different varieties of the rock to be identified. This preliminary result is seemingly in accordance with data from old historical literature, which stated the existence of six horizons in the Piperno formation.