AN EPR AND ISOTOPIC STUDY OF THE MARBLES OF THE TRAJAN's ARCH AT ANCONA: AN EXAMPLE OF ALLEGED HYMETTIAN PROVENANCE*

The provenance of 20 marble samples drawn from the Trajan's arch at Ancona, which is supposed to be made of Greek, Hymettian marble, has been established on the basis of the independent use of EPR and isotopic data. The results of the two methods are in good agreement and unequivocally indicate a Proconnesian provenance. Sixteen samples are assigned to this site, whereas two are classified as untypical Proconnesian samples and the remaining two are assigned an unlikely Parian provenance. No indication exists for a possible Hymettian origin of the marbles. A multi‐method approach, which employs all of the experimental variables simultaneously, demonstrates that the 18 samples identified as Proconnesian belong to several different quarrying areas within the site. This result is taken as an indication that the Proconnesian quarries were run following a highly organized, semi‐industrial production model. The origin of the Hymettian/Proconnesian misunderstanding and the possible misclassification of other Roman monuments in Italy are briefly commented on.     

EPR OF Mn2+ IMPURITIES IN CALCITE: A DETAILED STUDY PERTINENT TO MARBLE PROVENANCE DETERMINATION*

We demonstrate that the electron paramagnetic resonance spectrum of Mn²⁺ impurities in calcite, and therefore also in marble, may be accurately reproduced by a traditional spin Hamiltonian formalism. The success of such a treatment, however, very much depends on the spin Hamiltonian parameters having the correct signs as well as magnitudes. We present data that determine the sign of the axial anisotropy parameter and thereby facilitate future quantum mechanical characterizations of marble electron paramagnetic resonance spectra that supplement provenance determination.     

COMPOSITION PROFILES AND TIME EVOLUTION OF BURIED MARBLE PATINAS BY LA–ICP–MS AND LASER‐INDUCED MICRO‐PHOTO‐LUMINESCENCE

The present work aims to study surface composition profiles on buried marbles as well as their time evolution. Fifty samples from gravestones, buried for up to 80 years, were analysed by laser‐induced photoluminescence and LA–ICP–MS. The results include profiles of ²⁵Mg, ²⁷Al, ⁵⁵Mn, ⁵⁷Fe, ⁸⁸Sr and organic complexes of calcium, existing in the marble patina. The depth at which ⁸⁸Sr reaches its bulk value proved to be the best parameter to measure patina thickness. A diffusion model adopted from dissolution studies made on gravestones exposed to the atmosphere was successfully applied to the patina thickness data. The model fails to predict patina thicknesses for ancient excavated objects. However, it seems that ‘Sr alteration depth’ values alone can be used for discriminating ancient from recently buried surfaces.     

PROVENANCE OF MARBLES FROM NAXOS BASED ON MICROSTRUCTURAL AND GEOCHEMICAL CHARACTERIZATION

A detailed quantitative microstructural study coupled with cathodoluminescence and geochemical analyses on marbles from Naxos demonstrates that the analysis of microstructures is the most sensitive method to define the origin of marbles within, and between, different regions. Microstructure examination can only be used as an accurate provenance tool if a correction for the second‐phase content is considered. If second phases are not considered, a large spread of different microstructures occurs within sample sites, making a separation between neighbouring outcrops difficult or impossible. Moreover, this study shows that the origin of a marble is defined more precisely if the microstructural observations are coupled with cathodoluminescence data.     

NEUTRON ACTIVATION ANALYSIS AT THE BRITISH MUSEUM,LONDON

Neutron activation analysis was used at the British Museum from 1978 until 2002 for provenance studies on ceramics and marble. Significant numbers of the items analysed were of high quality and value, and careful sampling was necessary to avoid damage to the object. An in‐house British Museum Standard Pottery was established and inter‐calibrated with a number of standards used by other archaeometry laboratories. The results of the projects have been published in many papers, and the databases established will be of use to future scholars interested in the ceramic groups represented. Projects on Greek and Near Eastern pottery have been undertaken. Relatively large numbers of north European medieval and post‐medieval pottery samples were analysed, as well as the tin‐glazed ceramics of Spain and Italy. Classical marble has also formed the subject of another project and a database of quarry material has been established.     

INVESTIGATION OF ELECTRON PARAMAGNETIC RESONANCE PEAKS IN SOME POWDERED GREEK WHITE MARBLES*

Within the context of white marble provenance research, 42 powdered white Greek marbles have been characterized using electron paramagnetic resonance (EPR) spectroscopy. Phase analysis was first carried out to separate calcitic and dolomitic marbles, then EPR spectra of Mnuc were studied. Investigation of other marble EPR spectra, especially around g — 2.00, led us to characterize five different signals. The intensities of Mn²⁺ lines permit the separatum of eight quarries into two groups, allowing a first discrimination, in the g = 2,00 region, only one signal has been found to be useful for provenance research objectives. The results are cheering and should lead to many other similar experiments.     

Ionoluminescence and Cathodoluminescence in Marbles of Historic and Architectural Interest

Ion beam induced luminescence (IBIL) was applied, along with cathodoluminescence (CL), on seven samples of marbles of historic and architectural interest. The CL colours, observed in a cold cathode device, have been related to the IBIL spectra. Moreover, a detailed analysis of the IBIL spectral features has made it possible to disclose the influence of the chemical composition and to emphasize the crystal‐chemical role of the Mn²⁺. Beyond the chemical information and the crystal‐chemical interpretation, the spectra are recognized as being valuable in the field of archaeological studies for their significance as fingerprints of marbles, giving information on their nature and origin.     

PROVENANCE STUDY OF MARBLE ARTEFACTS FROM THE ROMAN BURIAL AREA OF FASCHENDORF (CARINTHIA,AUSTRIA)*

Numerous marble artefacts were among the extraordinary findings excavated at the Roman burial area of Faschendorf (Carinthia, Austria). The provenance of marble objects, particularly in the Roman provinces, is mostly unclear. Predominantly Mediterranean marbles have been used, but there are also some marble occurrences in the eastern Alpine regions that were exploited in those times. Besides a mineralogical–petrographic analysis, grain‐size evaluation in particular, and the determination of carbon and oxygen isotopes allow an effective characterization of the Faschendorf materials. Their provenance from the Gummern Marble complex in Carinthia is very likely.     

A New Methodology for the Provenance of Marble Based on EPR Spectroscopy

Fifteen years of research in investigating the characteristics of the EPR spectra of different types of white marble from several quarries in the Eastern Mediterranean has produced an accumulation of a large number of data, and much experience. Statistical treatment of these EPR data (statistical distributions and parameter correlations), has led to the selection of 10 parameters that are useful for quarry discrimination. Apart from the EPR parameters, the maximum grain size, measured with a stereomicroscope, has been found very useful. Boxplots have been found to be very useful as a first easy visual tool for evaluating the discrimination capacity of each parameter. On the basis of these results, a new methodology for determining the provenance of an archaeological sample was developed in stages, using a different pair or combination of parameters each time. In the first stage, the Penteli, Naxos, Hymettus and Proconnessus quarries are completely separated from each other. However, overlapping occurs between the parameter fields of Paros and Proconnessus, Paros and Hymettus and between the two archaic quarries of Melanes and Apollon on Naxos. If the sample is located in a non‐overlapping area, its provenance is obvious and easily determined. If the sample lies in one of the above three overlapping areas, an additional stage is necessary, in which other parameters are used to eliminate or decrease the overlap. Despite the partial overlapping of Paros with other quarries, the famous Lychnites marble of Paros, which was quarried underground, is clearly distinguished.     

AN UPDATED,MULTI‐METHOD DATABASE OF EPHESOS MARBLES,INCLUDING WHITE,GRECO SCRITTO AND BIGIO VARIETIES*

An updated database of Ephesos marbles including 244 samples from 16 quarrying districts is reported. The unknown Greco Scritto quarries near Hasançavuslar and the Bigio marbles from the quarries of Belevi and of Mt Panayir are also presented. The paper, however, is mostly devoted to the identification of the Ephesos white marbles, whereas the problems posed by the Bigio and Greco Scritto varieties are deferred to future work. The samples have been characterized by isotopic analysis, EPR spectroscopy and additional petrographic and optical properties. Owing to the complex geology of the region, the white marbles of Ephesos exhibit rather inhomogeneous properties and are conveniently classified into four marble groups, which can be almost completely discriminated. The problem of distinguishing the Ephesos white marbles from other similar varieties has been dealt with by statistically comparing the Ephesos samples with all the similar, medium‐grained varieties present in the marble database. Although some of the four Ephesos groups can be reliably identified, general solution of the discriminant problem is difficult. Historical archaeological information is needed to reduce the complexity of the problem by eliminating unlikely provenances. In this way relevant problems, such as the discrimination between Ephesos and Proconnesos marbles, can be solved.