Abstract - Vol LXXIX, September 2010 n. 2

- Stone properties and weathering phenomena of the Miocene Cusano Limestones (a.k.a. Perlato Royal Coreno): the case of the basement of the Santa Chiara Monastery bell tower (Naples - Italy).

- Cusano limestone is an ornamental stone cropping out in the central-southern italy and extensively used for the historical buildings construction with structural and architectonic purposes.
Artificial weathering experiments were conducted on Cusano limestones coming from La Valle and Canale quarries, located in the Benevento and Frosinone provinces (Italy) respectively. Rock specimens were subjected to standardized freeze-thaw cycles and salt crystallization tests; to this aim nondestructive and destructive tests were carried out including open porosity and p-wave velocity measurements and mechanical testing.
Finally the main deterioration morphologies affecting the Cusano limestone were identified through a detailed study on the façades of the bell tower of the Santa Chiara monastery in Naples.

- Mapping of the stones in the main façade of St. Giuliana castle (Umbertide, Italy).

- This article reports the mapping of the materials employed in the main façade of the medieval castle of St. Giuliana (XIII-XIV century A.D). This is one of the best examples of a fortified settlement, located on Mt. Corona (708 m a.s.l.) in Umbertide (N- W Umbria).
The main façade, made with stones of local origin, is particularly interesting for the extensive and unusual presence of travertine ashlars, which are completely absent in the walls of the other structural units of this castle and in the construction walls of the other medieval castles belonging to the neighbouring territory.
Travertine stone, is now almost rare in the surrounding area; there are only small outcrops of it on Mt. Corona near Ascagnano.
The other stones that were used are either sandstones (belonging to the Umbrian Marnoso - Arenacea fm) and limestones (belonging to the lithostratigraphic Scaglia Variegata and Scaglia Rossa fms, and the Maiolica fm) all coming from the southern side of Mt. Corona at low distance from the castle (less than 3 km). There are also some bricks from later building restorations.

- Spectroscopic characterization of a sepiolite-based Maya Blue pigment.

- Maya Blue, an ancient pigment used by Mayas in Mesoamerica, can be considered an ancestor of modern nano-composites as it forms by grinding and heating the guest indigo molecule with a hosting clay framework (palygorskite or sepiolite). Specific bonds form between the guest dye and the hosting matrix, conferring the pigment an exceptional stability to both acid and alkali attacks. While most works have been focused on the study of the palygorskite/indigo complex, this project is aimed to unveil the structural features of Maya Blue when sepiolite is the hosting framework. A freshly-synthesized sepiolite-based Maya Blue was prepared accordingly to ancient Mayas recipes and investigated with various spectroscopic techniques (Uv-visible, FTIR, Raman). All evidences show that by strongly crushing and heating (190°C in air or 150°C in vacuum) the sepiolite + indigo (2 wt%) composite, the dye aggregates dissociate to monomers favouring diffusion inside the clay tunnels emptied from loosely bound zeolitic H₂O. Once encapsulated indigo partly decomposes to dehydroindigo, its oxidized form, whose flexible molecule can easily diffuse inside the tunnels slightly changing the pigment colour (from deep blue to blue/green). Applied heating, however, does not cause loss of Mg-coordinated OH₂ which forms H-bonds with the indigo reactive groups (C=O and N–H) after encapsulation, thus stabilizing the composite. Spectroscopic evidences supporting presence of H-bonds are less evident in sepiolite-based rather than in palygorskite-based composites with indigo. In fact while indigo is perfectly juxtaposed in the narrower tunnels of palygorskite (6.4 x 3.7 Å), receiving H-bonds on both sides of the molecule, in the wider tunnels of sepiolite (10.6 x 3.7 Å) its molecule has to get near to one border in order to form a single bond. In a sepiolite-based Maya Blue pigment the global number of possible host/guest interactions is therefore dramatically halved with respect to a palygorskite-based one, inevitably reducing resistance to chemical attacks. Consequently, the extent of Maya Blue renowned stability is directly related to the composition of its main clay constituents.

- The source of stone building materials from the Pompeii archaeological area and its surroundings.

- This work is part of a large-scale survey carried out by the Deutsches Archäologisches Institut (DAI) of Berlin, which aim to locate the sources of raw building materials employed throughout various archaeological sites on the Sarno River plain (Pompeii, Nuceria, Stabiae, Longola, etc.) while also reconstructing the paleo-environments of this area during the Olocene. The present paper reports the preliminary results of a multidisciplinary project on the ancient stones used for construction in the town of Pompeii and other archaeological areas nearby (6^th century B.C.- A.D.79). The building stones used in these areas (volcanic and sedimentary carbonate rocks) have been analysed for their geological, mineralogical, petrographic and geochemical features and have been compared to rocks cropping out on the Sarno River plain - the possible provenances for these building material. Our data indicate that most of the stones employed for the edifices in Pompeii and other related archaeological sites between 6^th century B.C. and A.D. 79 originate from local quarries, mainly situated in several localities on the Sarno River plain itself and in surrounding areas.

- Colour and composition of nodules from the Calabrian clay deposits: a possible raw material for pigments production in Magna Graecia.

- Pliocene clays in Rocca Imperiale (North Calabria - italy) and Monasterace (South Calabria- Italy) have oxide and hydroxide iron nodules of a range of colours, varying from brown to red. It is likely that the inhabitants of some colonies in Magna Graecia (who already used the clay deposits to produce bricks) had detected the presence of the above-mentioned raw materials and decided to use them to produce mineral pigments and to decorate polychrome artefacts. The nodules were pulverized and analysed through SEM-EDS, XRPD and colorimetric analysis; further, they were heated at 275°C, 400°C, 550°C e 750°C, monitoring their mineralogical and chromatic transformations. Our study pointed out that it is possible to chemically differentiate the nodules of Monasterace from the nodules of Rocca Imperiale. Furthermore, our study proved that it is possible to produce mineral pigments by using such raw materials.

- Mineralogical, petrographic and chemical analyses for the study of the canvas “Cristo alla Colonna“ from Cosenza, Italy: a case study.

- A multi-technique study on materials used for the painting “Cristo alla Colonna” by Luigi Bria (private collection, Cosenza, Italy) was carried out for the first time during the restoration plan. Pigments, binder media and raw materials used for the application of ground and priming layers were studied using optical (OM) and electronic microscopy equipped with energy dispersive spectroscopy qualitative microanalysis (SEM-EDS), infrared spectroscopy (FTIR) and gas chromatography coupled with mass spectrometry (GC/MS). The goal of this study was to characterize this canvas and to set up a scientific aid and guide for its restoration, taking into account the, severe damage not exclusively due to natural decay processes. Our data can provide information about historical and stylistic background as well as advises for correct planning of the cleaning procedures.

- Archaeometric study of sub-geometric pottery found in Potenza, Italy: relationship and trade between near indigenous centers.

- Twenty pottery fragments from indigenous sites of Torre di Satriano and Baragiano (PZ, Italy) were studied using combined analytical techniques (OM, PXRD, XRF and SEM) to characterize their production centers and to better understand their manufacturing processes. Analyzed ceramics, characterized by a sub-geometrical decoration, are dated to VI sec. B.C. when a wide local pottery production was associated to a homogeneous phenomenon of diffusion of Greek products.
Torre di Satriano and Baragiano ceramics show similar petrographic features. Two groups are distinguished, a “less fine” Group 1 and a “more fine” Group 2. Mineralogical and morphological analyses suggest a firing temperature higher than 850°C as confirmed by the high degree of the groundmass vitrification. The chemical similarities between the pottery of Group 1 and the clay samples collected around the archaeological sites (Lucanian Basin sediments), might suggest a local provenance. Furthermore, the finest ceramic of Group 2 may have been locally produced following selection and levigation processes of the clayey materials. However, the chemical composition of the Group 2 ceramics may be related to a different raw material source-area. Only one fragment may be excluded from local production since it shows a different composition corroborating the archaeological hypothesis.

- Petrographic features, genesis and provenance of Pietra Paesina collections of the Regional Museum of Natural Sciences of Turin, Italy.

- Ruin marble outcropping in central italy always arose the contemplative interest of collectors and artists. With his geometrical, vividly edged and irregular colour patterns, this biomicrite, which is worldwide known as Pietra Paesina, remind painted landscapes or ruined villages. Even though the first aesthetical descriptions go back to XVII century, it was just in 1970 that Civitelli put a first light on the genesis of the rock, evidencing the non tectonic origin of its structure. Later on, the colour banding was correlated to the so called Liesegang phenomenon, with the periodical precipitation of iron oxyhydroxides following the infiltration of oxidizing ground waters during diagenesis and weathering. This works updates the previous hypotheses and demonstrate the possibility of mapping the concentration of diagnostic elements through different samples from Italian central-northern Apennines (Tuscany, Emilia Romagna, Southern Piedmont) by means of non-invasive techniques. Studying the Pietra Paesina ancient stone collections preserved in the Regional Museum of Natural Sciences of Turin, we compared the results of the traditional electron microbeam techniques with those of a bench-top micro-fluorescence instrument. With the limitations linked to the dimensions of the sample chamber, micro- XRF resulted to be a useful tool for the fully nondestructive analyses, allowing the distinction between different Italian varieties and setting the base for the provenance determination of ancient stone artifacts. Minor and trace elements quantification evidenced Mn, Sr and Ti concentrations as the most discriminatory parameters for provenance identification. Colour changes showed strict correlation to iron content, the percent variations depending on the composition of each sediment. Capillary forces controlling iron precipitation from weathering solutions are strongly influenced by the sedimentary structures, resulting in complex systems of dark bands and modifying the regular periodicity of Liesegang patterns.

- Italica (Seville, Spain): use of local marble in Augustan age.

- This study concerns 51 marble finds made of “Cipollino verde” coming from the ancient city of Italica (north of the modern city of Santiponce, 9 km NW of Seville, Spain), the earliest Roman settlement in Spain, founded in 206 B.C. The aim of this work was to determine their provenance from Greek and Italian quarries or from local quarries worked in the Iberian Peninsula.
Thin-section optical microscopy, X-ray powder diffraction, bulk rock chemistry and O, C and Sr stable isotope analyses were carried out. Results were compared with literature data on “Cipollino verde” marbles quarried in southern Euboea (Greece), Apuan Alps (Italy), Almería, Extremoz, Seville (Spain) and Évora (Portugal). These comparisons indicated twenty-five marble samples consistent with an origin from Italy (Corchia and Arni districts, Apuan Alps), twenty from Greece (Styra and Pyrgari districts, southern Euboea) and only six from Spain (Macael, Almería province).