Giuseppe Stella

Different approaches to date bricks from historical buildings

The application of Thermally (TL) and Optically (OSL) Stimulated Luminescence on bricks used as building material has allowed solving an chronological issue in the field of historical building dating.The possibility to use one or more methodologies of dating is closely related to the luminescent and granulometric characteristics of the sample. Using some brick samples collected in the church of Sain Seurin in Bordeaux (France), this paper discusses the implications and the possibility to use different approaches and techniques for dating. With this aim luminescence measurements were performed on both polymineral fine grain and quartz inclusion phases extracted from each brick. For Equivalent Dose (ED) and consequently age determination, TL on mixed fine grain fraction (FG), OSL on quartz inclusions (QI) and on mixed fine grain (FG*) fraction, were used. The results obtained suggest the advantage of using OSL technique on fine grain fraction cleaned up by IR stimulation (FG*), but the use of quartz inclusion represents indeed a good alternative.

Historical Survey and Chronology of Bonajuto Chapel in Catania, Italy

Located in the historical center of Catania, Italy, in the Civita district, the Bonajuto Chapel is one of the oldest and best-conserved buildings of the city, which has survived the numerous earthquakes that struck eastern Sicily during the medieval and the modern ages, such as those particularly devastating in 1169 and 1693. However, both the date of this small monument, as well as its original use, still remain uncertain, as literary and documentary evidence are scarce and fragmentary. Most historians, analyzing prevalently the stylistic and constructive aspects, interpreted the chapel as a place of worship and assigned its construction to a rather long period of the early Middle Ages, from the 5th or 6th centuries ad to the 8th or 9th centuries ad—the phase during which the island was under the Byzantine domination. The excavations carried out in 1930 to 1939 and the last restoration works (in 2003) have not provided explicit chronological data. Its age determination is considered essential for a better knowledge of the real influence of this domination on the architecture of the Island. Therefore, a multidisciplinary and accurate analysis of the building using the existing bibliography has been carried out also in order to understand the functional and morphological transformations of the chapel during its long life. The thermoluminescence absolute dating methodology applied to some brickwork elements of the construction, has placed the monument chronology in a period of time that is notably shorter than that previously noted here. These new data, with the study of the architectural structure, have made a significant step forward in the knowledge of the chapel history.

Historical building dating: A multidisciplinary study of the Convento de São Francisco (Coimbra, Portugal)

Abstract Cross-dating of bricks and mortars from historical building, through thermal (TL) and optically stimulated (OSL) luminescence have achieved good accuracy and precision. However this approach is, in many cases, not exhaustive especially for buildings with different construction phases closely temporally spaced to each other. The uncertainties of experimental data added to the reuse of old bricks and/or the presence of mortars applied on restorations represent the main limits to obtain the complete chronology. In the case of the Convento de S. Francisco (Coimbra, Portugal), the dating results were crossed with the stratigraphic study of the building, mineralogical characterization by XRD and colorimetric data of the mortar samples. Thanks to luminescence ages, mineralogical composition and color specification, two phases of construction were identified: the first from the 17th century and the first half of the 18th century and the second from the second half of the 18th century to the first half of the 19th century. These results were confirmed by mineralogical characterization and colorimetric measurements of mortars that identify two different types of materials in aggregate/binder ratio terms and superficial optical characteristics.

Investigation by pXRF of Caltagirone Pottery Samples Produced in Laboratory

Abstract In the study of archaeological ceramics, it is important to have compositional data to identify their origin and source. The fabric also provides useful information on the production technology, especially with regard to the firing steps. The work presented here is connected to this field and focuses on the main parameters related to the terracotta artefacts preparation. Thus, one can consider the effects in terracotta characteristics of different raw materials and firing parameters, in particular for pottery of Caltagirone, which is one of most important centres of pottery production in Italy, active since the Neolithic. To this end, terracotta samples have been reproduced in a laboratory setting according to the ancient procedure of Caltagirone manufacture, starting from clay and degreaser extraction in local historical sites. The analysis was conducted using a portable X-Ray Fluorescence (pXRF) spectrometer for elemental characterization of sand degreaser and of clays during each step of the realization process and in different firing conditions. SEM-ED techniques were also employed to verify the method and results for some of the samples after firing process. Framing the technological context of manufacture production, known in the specific case, it is also possible to identify potential outcomes and limits in the study of potsherds using pXRF technology, in applying the methodology to historic artefacts.

ESR and U/Th Dating Methodologies Applied to Carbonates from Southern Italy

Since the dating of a stalactite from the Akiyoshi cave in Japan by Ikeya (1975), significant progress has been made in the utilisation of electron spin resonance spectroscopy (ESR) for the assessment of past radiation doses in the context of archaeological and geological dating (Rink 1997). The method is applicable to various materials such as speleothems, spring deposited travertines, mollusc shells and corals (Grun 1989). Discoveries of human remains in Western Europe have been proposed to indicate the sites of the earliest arrival of humans there, and have been dated to the Early Pleistocene by ESR using quartz and tooth enamel (Falgueres 2003). The researches based on the dating of quartz allow the age assessment of heated ceramics, volcanic rocks, intrafault material, or windblown sediments (Grun 1989). The method is also used on archaeological artefacts made of obsidian, which are precious for archaeologists, allowing them to obtain information about cultural, social and economic relations between prehistoric populations (Duttine et al. 2003).