Characterization of glaze ceramics from the archaeological site of La Alcazaba, Almería (Spain)

Abstract

The Alcazaba de Almería is one of the most impressive mediaeval remains in Al-Andalus. Its defensive walls are expression of the economic and strategic relevance of Almeria City during middle Ages. In the course of archaeological excavations in this monumental area, several glazed ceramic remains were found in the palatine area so-called second enclosure. They are dated back between the 10th and the 15th centuries and correspond to small fragments on which different decorative techniques can be identified: green and manganese, green glazed, cuerda seca total, Nazarí Black and White, lustreware and blue and lustre earthenware. Although only seven samples out of 35 selected samples have been analyzed, their interest lie on that they are the first analytical approach to the ceramics of this important archaeological site and the group is representative some of most typical decorative procedures employed in Al-Andalus.The combination of ion beam and nuclear non-destructive analytical techniques performed on these ceramics have allowed the discussion on several aspects of the production technology, as the use of raw materials, and the degradation processes suffered by them. Glaze composition is discussed first. It is characterized by high values of Pb, Sn, Na, K and Mg. Chromophores are identified and some raw materials are discarded (psilomelane for manganese black) or proposed (absolite, skutterudite and trianite for blue). Secondly, the most degraded samples are found to be characterized by high values of Cl, in an inverse relation with the content of Si. The surface of two samples with lustre decorations, one with Cu particles and one with Cu+Ag particles, are studied finding a progressive decrease of Pb in the surface. Finally, the pastes of the samples are characterized by high values of Ca with respect to other ceramics of the area. Similar values are found in ceramics from Manises and Sevilla. The case of a possible imported sample is also discussed.