Ceramics of the Crusader period found in Acre: An INAA and ICP study of the local productions and of some imports from the Byzantine world

The growing interest of scholars in ceramics of the late Byzantine period, or Crusader period in the Holy Land (12th to 13th century), is progressively leading to a better typological and chronological definition of its characteristic types. This evolution is apparent through the recent publication of material from important Byzantine sites such as St. Polyeucte (Saraçhane) in Istanbul [1], the consideration now attached to these categories of wares in the excavations (e.g. in Pergamon [2]), the publication of collections from museums [3], the - still seldom - organization of specific colloquiums [4,5] as well as through the publication of Crusader material from several sites in the Latin Kingdom of Jerusalem [6,7,8,9,10]. Nevertheless, very little is known about the manufacturing centers of late Byzantine and Frankish wares and about the patterns of diffusion of their products. A major contribution to this question can be obtained from elemental and petrographical analysis of the paste constituting the ceramics. Such methods are able to identify the provenance of ceramics by comparison with reference groups of known origin. Comprehensive analytical programs using sherds from attested production centers have been pioneered in the 1980's by Megaw and Jones [11] and are expected to be developed in the future [12] to support research in Byzantine ceramology. In this framework, the study of material from the recent excavations in Acre may shed some new light on the relationships between the Levant and the Byzantine world during the Crusader period. Acre was the main harbour of the Latin Kingdom of Jerusalem and became its capital in 1191, after the seizure of Jerusalem by Salah-el-Din. An important part of the maritime trade with the Crusader kingdoms, especially through Italian merchants, was directed to it. Excavations have been carried out by the Israel Antiquities Authority in different parts of Acre, mainly in the Hospitallers Complex [13], built in the 12th century by the knights of the order of St. John, in a tower and part of the 13th century wall and moat [14], and in some other sites throughout the old city in dwellings and commercial areas [15]. Ceramic finds are currently under study [8,9] and show a diversity of sources which illustrate links with the eastern part of the Mediterranean: Byzance, Cyprus, the Aegean, Christian and Islamic Syria, as well as with the western Mediterranean: Italy, North Africa Some of these sources can be identified from the typological features (e.g. St Symeon ware known to have been manufactured in the Syrian port of Al Mina [16]), but in most cases ceramics are refered to by their type and supposed broad region of origin, and therefore some accuracy can be gained from an analytical study. The present INAA (Instrumental Neutron Activation Analysis) and ICP-AES (Inductively Coupled Plasma - Atomic Emission Spectrometry) program focuses on two categories of ceramics excavated in Acre and serves a double aim. The first aim is to define and characterize the local productions of Acre and to set a new analytical reference for the ceramics production centers of the late Byzantine / Crusader period. The second is to investigate some imports related to the Byzantine world, and especially, in the present case, the type known as "Zeuxippus ware" [17]. This type corresponds to a fine, glazed ware decorated with the sgraffito technique. It is of particular interest for the period both because of the extent of its diffusion (Fig.1) and because its decorative patterns have been a main source of inspiration for the 13th century productions [18]. ICP-AES and INAA elemental analysis are used in a complementary way to determine a range of elements which includes the major and minor elements as well as a variety of traces of different geochemical behavior. Rare earths (La, Ce, Nd, Sm, Tb, Yb, Lu), some transition elements (Sc, Co, Cr), some major elements (Na, (K, Ca), Fe) and (Rb), Sb, Cs, Hf, Ta, Th and U are determined by INAA with the external standard method, using Perlman-Asaro standard as reference [19]. The analytical protocol involves 3 countings with a planar, high resolution Ge detector for low energy gamma-rays (below 400 keV) [20] and a larger Ge detector of higher efficiency for higher energy gamma-rays. ICP-AES is mainly used here to determine major elements, together with minor and trace elements not determined by INAA such as V, Mn, Ni, Cu, Zn, Sr, Y. Alkaline elements cannot be analyzed as a consequence of the dissolution process, which involves fusing in a furnace with Na₂O₂ and subsequent dissolution in water with HNO₃ addition [21]. Sc serves as internal standard for the control of physical effects in the plasma. Various rock standards are used for calibration. The ICP and INAA measurements include an intercalibration program which is designed to enable us to compare our results with the ICP-based database currently under development in Oxford [12] and with data on similar ceramics from Asia Minor (including Zeuxippus ware derivatives) previously investigated by PIXE and INAA [22]. The first part of our project involves the analysis of different kind of wares which are suspected to be local. Evidence for local production has been found in the form of wasters of a type of bowl which is unique to Acre - thus named "Acre bowl". Since large quantities of these bowls were unearthed in the courtyard of the Hospitallers Complex, it seems that they were probably used for feeding the pilgrims or the sick in the Hospice [8]. They were found in smaller quantities in all other excavated sites in Acre, and do not appear in other excavated sites in the Latin Kingdom of Jerusalem, apart from some rural sites in the close vicinity of Acre. Previous petrographic analysis of a sampling of Acre bowls has shown that, despite a fabric that appears to be uniform to the eye, two different groups of pastes can be distinguished [23]. One group corresponds to the geological features of the region of Acre and can be considered as local. The other is related to a geological context which can be found in southern Lebanon. The import of such simple, unglazed ware as the Acre bowls has been interpreted as a consequence of the need for additional stock in periods of heavy pilgrimage [8]. In spite of this rather unusually complicated feature, elemental analysis of wasters of Acre bowls is expected to enable us to define the range of locally manufactured products. Apart from Acre bowls and wasters, the sampling includes amphorae - some presumably local and some presumably imported -, glazed cooking pots, and glazed bowls decorated in the sgraffito, slip-painted and reserved slip techniques. The cooking pots have already attracted some attention in the literature since a street of cooking pots makers is known to have existed in Acre in the 13th century [24]. Furthermore, similar glazed cooking pots have been found in Paphos (Cyprus), where they appear as imports according to analyses by atomic emission spectrometry [11]. The evidence for the export of such wares, which seem to derive from an earlier Palestinian tradition, from the Crusader mainland would be of some interest in terms of economic and cultural history [7].