TIN-RICH SURFACES ON BRONZE–SOME EXPERIMENTAL AND ARCHAEOLOGICAL CONSIDERATIONS

Tin-rich surfaces found on bronze antiquities may be the result of man-made or natural processes. The difficulties encountered in distinguishing between these processes are discussed and illustrated with reference to the surface structures obtained on experimentally tinned copper and bronze. Heat treatments were carried out on the experimental material to allow observation of the growth of the intermetallic compound layers on the surface, and of changes that occur at various significant temperatures. The experimental reduction of cassiterite directly onto the surface of copper and bronze is illustrated for the first time. Examples of tin-rich surfaces found on various antiquities are illustrated and are compared with the experimental material for interpretation. Scanning electron microscopy and microanalysis were the primary tools used in this study.     

MICROCHEMICAL CHARACTERIZATION OF BUILDING STONE FROM SEVILLE CATHEDRAL,SPAIN

Enrichment diagrams for trace elements have been proposed as a useful and straightforward procedure to identify ores and stones. The identification of the diverse stone of the exterior of the Cathedral of Seville has been achieved by this means. Fourteen trace elements have been analysed, from both quarry and building material samples, using atomic absorption and flame emission spectrometry in order to apply enrichment diagrams for identification purposes.     

EVIDENCE FOR CHURCH ORIENTATION BY MAGNETIC COMPASS IN TWELFTH-CENTURY DENMARK

The orientations of some 570 Romanesque churches (one-third of the total) from four regions in Denmark show significant differences in the claimed east-west orientation, being typically rotated 5-15° clockwise from true east-west. Magnetic declination was predominantly easterly between AD 1000 and 1600; the church deviations probably originate from sometimes using a magnetic compass, other simple and plausible causes for this ‘skewness’, for example orientation by the sun at specific periods of the year or astronomical alignment, being hard to design. Hence, some 25% of the churches were probably oriented by means of a magnetic compass. As a tool for dating, the orientations have not yet been successful due to statistical scatter. Church building in Denmark boomed in the twelfth century. The early history of the compass is somewhat uncertain. The first European reference known is from about 1190-1200, while the oldest Norse source is from about 1225 (Landnámabók), saying that the lodestone was not known before. Danish churches thus bring new information about the early use of the magnetic compass in Europe.     

PROVENANCE DETERMINATION OF NEOLITHIC TO CLASSICAL MEDITERRANEAN MARBLES BY STABLE ISOTOPES*

Two stable isotopic data bases for ?¹³C and ?¹⁸O values of marble have been accumulated: (1) 590 analyses from 42 Classical quarries of Greece, western Turkey, Tunisia, and Carrara, Italy, and (2) potential Early Bronze Age (EBA) marble sources in the central Cyclades, comprising 192 analyses from 16 sites on the islands of Paros, Naxos, Ios, and Keros. The data bases include the most important marble occurrences in the eastern Mediterranean and so can be used to source artefacts of any age. Neolithic artefacts found at Franchthi Cave, where no marble occurs locally, have been attributed to the Peloponnese and the Cyclades, direct evidence for early trade. In the Cycladic EBA, Naxos and Keros were the principal marble sources for the abundant artefacts found at Keros. The commercial marble trade in Archaic Greece began in the central Cyclades where the tradition apparently went back some 5000 years, to the Neolithic. Classical Greece and especially Rome expanded the number and locations of commercial marble sources throughout the Mediterranean.