Catalan Imitations of the Ligurian Taches Noires Ware in Barcelona (18th\u201319th Century): An Example of Technical Knowledge Transfer

The ware called Taches Noires was developed in Albisola (Liguria, NW Italy) during the 18th century. In just a few years, it spread all over the Mediterranean (Italy, France, Spain, Tunisia, and Greece) and also in the New World (Canada, the Caribbean Islands, and Mexico). The success of the Taches Noires ware was so massive that it was soon copied by Spanish and French workshops. A collection of Catalan imitations and Ligurian imports found in Barcelona were analysed and compared to previously existing data from Barcelona productions, as well as reference samples from Albisola. The study proved the presence of both local imitations and original Albisola imports. The analysis showed a homogeneous product of high technical quality for the Albisola pottery. On the contrary, the local imitations presented a greater diversification in the choice and manipulation of the raw materials, probably related to the existence of different workshops engaged in the manufacturing of these products. Nevertheless, for one of the local groups, ceramists adopted a glaze recipe similar to the one used in Albisola, clearly indicating a direct transfer of knowledge, and possibly of potters, from Albisola to Barcelona

Synchrotron tts-\ub5XRD identification of secondary phases in ancient ceramics

The study of the alteration process, and in particular of secondary phases precipitated in pottery after its production, can constrain the post-depositional environments or the type of use of the pottery. Detailed study of secondary phases can be done using different approaches, based on microscopic, microstructural and microchemical analyses, as well as mineralogical methods. In the present study are reported the results of the application of punctual mineralogical analysis by synchrotron through-the-substrate microdiffraction (tts-\u3bcXRD) to analyse secondary phases precipitated in ancient pottery (Bronze Age pottery form Frattesina in Italy and Mesolithic pottery form Al Khiday in Sudan). Although the chemical composition of these secondary phases in many cases almost matches with the stoichiometric composition of a known mineral, only some of them were actually true mineral phases (i.e. with crystallinity and therefore showing diffraction peaks), while others were amorphous. Some phases, the occurrence of which was previously attested only on the basis of their chemical composition (determined by scanning electron microscope or the electron microprobe analysis), were univocally identified as true vivianite (Fe3(PO4)2\u20228H2O) and crandallite (CaAl3(PO4)2(OH)5\u2022H2O) minerals. Part of the phases detected in studied pottery, the chemical composition of which was consistent with specific mineral phases, were instead amorphous. The synchrotron through-the-substrate microdiffraction (tts-\u3bcXRD), therefore, represents a valid method for properly determine the mineralogical nature of secondary phases in pottery, as well as other small-sized and rare mineral phases occurring in polycrystalline materials of archaeological interest, such as pottery, mortars, painting and glassy materials

Comparison between different image acquisition methods for grain-size analysis and quantification of ceramic inclusions by digital image processing: how much similar are the results?

This paper focuses on the statistical comparison between the abundance and grain-size distribution of inclusions in pottery, determined by digital image process on images acquired using different methods (crossed-polarized light optical microscopy, back-scattered scanning electron microscopy (SEM) and microchemical mapping also under SEM). The results clearly indicate that the acquisition method deeply affects the absolute quantification, resulting in highly underestimated values for crossed-polarized light images with respect to those obtained from the microchemical mapping. Besides absolute quantification, the grain-size distribution shows some small differences among acquisition methods both in mean and variance values although frequency distributions and cumulative curves of inclusions show some similarities regardless of the acquisition method. Differences in terms of abundance and grain-size distribution of inclusions on the same sample are here analysed and related to the limitations of each acquisition metho

Provenance and reference groups of African Red Slip ware based on statistical analysis of chemical data and REE

African Red Slip (ARS) ware (sigillata africana) from three archaeological sites in northern (Oudhna, Sidi Khalifa) and central Tunisia (Henchir el Guellel) was studied by X-ray fluorescence and statistical treatment of chemical data in order to define homogeneous reference groups. The specimens from Henchir el Guellel are clearly different from those of the other two sites, which are compositionally more similar, due to their geographical vicinity. ARS ware from Sidi Khalifa is chemically very homogeneous, whereas that from Oudhna clusters into two distinct groups. The chemical correspondence with literature reference groups, based on both kiln wastes and sherds from archaeological surveys, defines new reference groups, statistically more numerous and representative. Comparisons of chemical data by neutron activation analysis on selected potsherds and clays from the surroundings of each site also identified the probable base-clays used to produce the ARS ware of Oudhna, Sidi Khalifa, and to advance some hypothesis on that used in Henchir el Guellel, thereby overcoming difficulties in assessing chemical contents of elements due to levigation processes

African terra sigillata from Henchir Es-Srira archaeological site, central Tunisia: Archaeological provenance and raw materials based on chemical analysis

Terra sigillata from the Henchir Es-Srira archaeological site in central Tunisia was analysed by X-ray fluorescence (XRF), and chemical data were statistically treated by multivariate (principal component and cluster) analyses, which defined a geochemically homogeneous reference group. According to our results, potsherds from Henchir Es-Srira are compositionally compatible with the six reference samples from the same site already published in the literature, and form a single group. A larger reference group is now well established for this site. In addition, comparisons with previous data from other sites in both northern and central Tunisia show that terra sigillata from Henchir Es-Srira is chemically more similar to that of the northern sites than the central ones. Neutron activation analysis (NAA), an extremely valuable tool for provenance studies, was also performed on a set of selected potsherds from Henchir Es-Srira and clay materials collected nearby, with the aim of identifying the possible clayey raw materials used for this ceramic production. Comparisons of both bulk chemical composition and trace and rare earth element (REE) patterns show that most of the objects were locally produced from a Neogene base-clay, probably collected from the \u201cSaouaf Formation\u201d