Elsevier

Applied Clay Science

Volume 197, 1 November 2020, 105795
Applied Clay Science

Research Paper
The Phoenician Red Slip Ware from Sulky (Sardinia-Italy): Microstructure and quantitative phase analysis

https://doi.org/10.1016/j.clay.2020.105795Get rights and content

Highlights

  • We analysed a set of Phoenician Red Slip Ware from Sulky (Sardinia).

  • XRPD analysis gave information of clays and inclusions of raw materials.

  • QPA revealed the unusual association of quartz + cristobalite + tridymite.

  • EPMA data showed an Fe-enrichment in the red slip.

  • The nature of the inclusions in the ceramic paste is compatible with local geology.

Abstract

This study is focused on the Red Slip Ware from the archaeological site of Sulky (Sardinia, Italy), dated back to the end of 9th to the early 8th centuries B.C. Optical Microscopy (OM), X-ray Powder Diffraction (XRPD) and Scanning Electron Microscopy coupled with an EDS system (SEM-EDS) were used to characterize both the body and the external Red Slip decoration. Quantitative phase analysis (QPA) by the full-pattern refinement based on Rietveld code and Electron Probe Microanalyzer (EPMA) along with petrographic analysis suggested a temperature of firing in the range of 800–900 °C in oxidizing conditions. The quartz + cristobalite + tridymite association, inherited from the ignimbrites of the Sulcis volcanic district, could be useful to discriminate the Red Slip Ware production of Sulky from other manufactures. The slip presents major amount of hematite respect to the body, probably due to the use of the pigment to enhance the colour of the surface.

Introduction

The Red Slip Ware (RSW) is an important ceramic marker that occurs in all contexts of the Phoenicians occupation, thus helping to identify their presence on the territory. These ceramics owe their name to a shiny deep red slip applied to the surface. This slip characterized RSW, giving to the artefacts a very similar external appearance (Bartoloni, 1991, Bartoloni, 1992; Nigro and Spagnoli, 2017; Spagnoli, 2019).

It is important to avoid confusing this ceramic class with the Late Roman Fine Wares, a diffuse and important class of ceramics also known as Red Slip Wares. This class of ceramic was diffused in specific areas of the Roman Empire including Turkey, Cyprus, southern Asia Minor or Africa. It was used from the 4th to the 7th century A.D. (Jackson et al., 2012) and it is more recent than Phoenician RSW, that appeared since the 11th century B.C. in the Levant (Bikái, 1978). Moreover, 3-D decorations were disused on this class of ceramics (Jackson et al., 2012), usually absent in most of the Phoenicians RSW artefact (Bikái, 1978; Nigro and Spagnoli, 2017).

Despite the great importance of RSW and its connection with Phoenician culture, only a limited number of works are focused on this class and on Phoenician ceramics in general (De Vito et al., 2014; Amadori et al., 2017; Shoval, 2017; Fabrizi et al., 2019, Fabrizi et al., 2020; Vieira Ferreira et al., 2019).

The aim of this work is to explore the nature of the raw materials and the technological background involved in the production of the RSW from the Phoenician archaeological site of Sulky (Sardinia, Italy).

Quantitative data are fundamental to discriminate ceramic with similar appearance that were produced by different production centres. In this perspective, XRPD was performed in transmission mode, requiring only a few mg of powder and allowing the elaboration of data by the Rietveld method. These data allowed to accurately quantify the mineralogical association and minor phases occurring in both the paste and the thin slip (Ballirano et al., 2014; De Vito et al., 2015), which helped to identify phase transitions induced by firing and mineral markers to correlate the raw materials with the local geology. Electron Probe Microanalyzer (EPMA) was applied to determine the nature of the raw materials (De Vito et al., 2017; Enea-Giurgiu et al., 2019), the occurrence of clay sources (Meunier, 2005), and to highlight the main features of the slip (Shalvi et al., 2019). In addition, quantitative chemical data were useful to distinguish the RSW produced in Sulky from that of other archaeological centres.

These data were also compared with the RSW produced in Motya, another important Phoenician context, bringing to light interesting analogies and meaningful differences.

Section snippets

Geological setting

Sant'Antioco (Fig. 1) is a small island in the extreme south-western part of Sardinia (Italy). The island is one of the southernmost part of the calc-alkaline volcanic belt (late Eocene-middle Miocene), extending along the western coast of Sardinia and Sulcis volcanic district (Araña et al., 1974; Pioli and Rosi, 2005; Conte et al., 2010). This area is characterized by quaternary deposits of clays, silt and sand. The igneous rocks of the island of Sant'Antioco (together with the nearby island

Materials and methods

Eight fragments of RSW (Fig. 2) unearthed in the small “Cronicario” area of the ancient Phoenician city of Sulky (Sardinia, Italy) were selected for this study (Table 1). They come from recent excavations carried out during the 2014 season, from the most ancient stratigraphic archaeological layers, in a particular deposition context previously published (Guirguis, 2019).

All samples show a Red Slip layer in the uppermost part of the ceramic samples, ranging from a poor to a medium brightness,

Petrographic analysis

The results of petrographic analysis highlighted the presence of one main fabric, showing homogeneous mineralogical and petrographic features. Only one sample (CRON 3856 – S7) was different from the others, showing coarser grain size of the inclusions. A summary of the petrographic analysis of each sample is reported in Table 1.

The fabric (Fig. 3 a, b) was characterized by a medium grain size, with frequent presence of quartz and K-feldspar inclusions, along with igneous rocks (with

Production technologies and provenance of the raw materials

The results indicated that size and distribution of the inclusions, micro-structure and texture of the porosity and matrix are very similar among samples, suggesting a common practice of selection of the raw materials and forming methods as well as firing conditions.

The unimodal grain size distribution excluded the addition of tempers in the paste and lead to the hypothesis that these inclusions occurred in the natural clay. Nevertheless, a rough selection of precursor materials was applied. In

Conclusion

The study of the Phoenician RSW artefacts from Sulky (Sardinia, Italy) by means of a multi-analytical approach provided information about the nature of the raw materials, their selection, technological process of production, firing conditions and the application of the superficial slip.

The main conclusions are:

  • 1)

    The crystalline matrix, the incomplete decomposition of illite and presence of new-formed hematite indicate firing temperatures in the range of 800–900 °C for Ca-poor ceramics;

  • 2)

    The

Credit author statement

C. De Vito and L. Fabrizi. designed the study and planned the experiments and interpreted O.M, SEM-EDS and EPMA data and wrote the manuscripts with the contribution of the other authors.

M. Guirguis. and L.Nigro carried out the collection of the samples.

P. Ballirano acquired XRPD data and performed the QPA.

L. Medeghini and F. Spagnoli helped in the interpretation of scientific and archaeological data.

Author contribution

L.N. and M.G. carried out the collection of the samples. P·B acquired XRPD data and performed the QPA.

C.D. and L.F. designed the study and planned the experiments and interpreted O.M, SEM-EDS and EPMA data and wrote the manuscripts with the contributions of the other authors.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

Financial support was provided by Sapienza University of Rome (Ateneo funding, 2016, 2018) and Ministero dell'Istruzione, dell'Università e della Ricerca (funding FFABR 2017 and Ateneo 2018). PhD grants of the Department of Earth Sciences and Sapienza University of Rome are gratefully acknowledged. The study and collection of samples are carried out as part of the research conducted by the University of Sassari in the ancient settlement of Sulky (funding “Fondo di Ateneo per la Ricerca 2019”):

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