## 4 Conclusions  
The results of this study allowed the characterization of the pottery production from Albarracin _Taifa_ in the 11-12 th centuries CE, and establishing differences and similarities with Islamic productions manufactured in other _Taifa_ kingdoms of the Iberian Peninsula during the same period. The analyses carried out on the ceramic bodies confirmed that the selection of raw materials depended on the decoration to be applied afterwards. All the samples had a Ca-rich body in order to obtain buff colors and to avoid cracking during firing process. Firing process depended on the kind of decoration. Tin-opacified glazes were applied on pre-fired clay bodies, but _cuerda-seca_ and transparent yellow/honey glazes were applied on the unfired clay body. Once again, this differentiation between the two techniques implies a specialization of the potters. Concerning to the decoration, it can be pointed out some conclusions about Albarracin production. Glazes manufactured in Albarracin _Taifa_ during 11 th century CE were rich in lead and silicon oxides. Their composition ranged from 32% to 48% PbO and from 36 to 49% SiO2, but differences could be established between white tin-opacified and colored glazes. Secondary-side glazes had similar compositions, although the number of inclusions and the size of them were in both cases bigger. However, the thickness of the coatings was  
Figure 7: Lead-isotope ratios of glazes from different ceramics (white tin-opacified glazes, honey glazes, and green glazes from Albarracin; glazes from Zaragoza workshops (white tin-opacified glaze is marked with a red circle); and glaze in a sample from Pechina): (**a**) \({}^{208}\)Pb/\({}^{206}\)Pb ratio vs. \({}^{207}\)Pb/\({}^{206}\)Pb ratio; (**b**) \({}^{206}\)Pb/\({}^{204}\)Pb ratio vs. \({}^{207}\)Pb/\({}^{206}\)Pb ratio. thinner on the less important side. Those features corroborated the idea of a specialization and knowledge of the techniques of production. As well as silicon and lead as main components, tin-opacified glazes included cassiterite crystals that were responsible for opacity. The buffer color of the bodies required only ~7% SnO\({}_{2}\). Tin-oxide crystals were well distributed inside the glazes, and the size of them (<800 nm) was an important factor to achieve the opacification. Green monochrome glazes were always opacified with tin oxide. However, opacity in _cuerda-seca_ samples was reached by the combination of tin oxide plus undissolved grains of quartz. This technique of opacification was also used in the south of Iberian Peninsula in the 10 th century CE. Copper, iron, and manganese oxides were added to the glazes to obtain, respectively, green, yellow, and black glazes. Manganese oxide was employed to draw the black lines that described the designs of _cuerda-seca_ specimens. Comparing the lead/silicon ratios used in the manufacture of ceramics with transparent and tin-opacified glazes in Albarracin _Taifa_ with other production centers of the Iberian Peninsula during the Islamic period, we can conclude that PbO/SiO\({}_{2}\) ratios were lower in the northeastern workshops than in the southern ones. However, the potassium content was higher in the northeastern centers. In all the studied ceramic workshops of the Iberian Peninsula, tin-opacified glazes were applied on a biscuited body, as in Albarracin _Taifa_. However, there existed differences in transparent glazes, because the southern workshops seemed to use a double firing for producing this type of glaze. In the case of _cuerda-seca_ decoration, the production of Albarracin had more similarities in the method of opacity and in the lead/silicon ratios with southern workshops; however, for the firing method, Albarracin samples followed a single firing process, as with the Zaragoza and Almeria centers.