FINE WARE FROM LOCRI EPIZEPHIRI: A PROVENANCE STUDY BY INDUCTIVELY COUPLED PLASMA EMISSION SPECTROSCOPY

Fifty-six sherds of fine ware from Locri Epizephiri were analysed by inductively coupled plasma optical emission spectroscopy (ICPOES) and flame emission spectroscopy (FES). The sherds had been excavated on the archaeological areas of Marasà Sud, Centocamere and San Cono, and represent local and imported products from the seventh to the second century BC. The samples were dissolved by fusion with lithium metaborate and analysed for nine elements (Al, Fe, Ca, Mg, Ti, Mn, Sr, Ba and Cr) by ICPOES, while Na and K were determined by FES. The analytical data were subjected to hierarchical agglomerative clustering and principal components analysis to classify the sherds into compositional groups. The results obtained indicated that Corinthian, Attic and Ionian products or imitations may be classified in a few separate groups, while most local products are found in a unique, large group.     

MICRO‐RAMAN SPECTROSCOPY CHARACTERIZATION OF DELLA ROBBIA GLAZES*

Micro‐Raman spectroscopy and the laser‐induced transformation technique were used for systematic study of five coloured glazes on Saint John the Baptist (29 inch tondo), a majolica terracotta relief attributed to Luca Della Robbia and on permanent exhibit in The John and Mable Ringling Museum of Art. We suggest that ions in a lead silicate matrix, called ‘lead ultramarine’, could contribute to the famous Della Robbia blue colour, in addition to the effect of Co atoms as suggested previously by Pappalardo et al. (2004 ). The original yellow glaze contains lead(II) antimonate. The green is a mixture of the yellow and blue pigments, the brown contains hematite, and the white glaze contains tin dioxide as an opacifier. The use of lead oxide as a main fluxing agent is confirmed by laser‐induced micro‐crystallization.     

THE ANALYSIS OF SEA TURTLE AND BOVID KERATIN ARTEFACTS USING DRIFT SPECTROSCOPY AND DISCRIMINANT ANALYSIS*

We investigated the utility of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) for the analysis and identification of sea turtle (Family Cheloniidae) and bovid (Family Bovidae) keratins, commonly used to manufacture historic artefacts. Spectral libraries are helpful in determining the class of the material (i.e., keratin versus plastics), but do not allow for inferences about the species source of keratin. Mathematical post‐processing of the spectra employing discriminant analysis provided a useful statistical tool to differentiate tortoiseshell from bovid horn keratin. All keratin standards used in this study (n = 35 Bovidae; n = 24 Cheloniidae) were correctly classified with the discriminant analysis. A resulting performance index of 95.7% shows that DRIFTS, combined with discriminant analysis, is a powerful quantitative technique for distinguishing sea turtle and bovid keratins commonly encountered in museum collections and the modern wildlife trade.     

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.     

OCCURRENCES OF GREEN EARTH PIGMENT ON NORTHWEST COAST FIRST NATIONS PAINTED OBJECTS*

An analytical study of First Nations painted objects from the Northwest Coast showed that green earth (celadonite) was used as a green pigment by Tlingit, Haida and Tsimshian artists. Green earth appears to have been used less frequently by Heiltsuk and Kwakwa ka ’wakw artists and was not found on Coast Salish or Nuu‐chah‐nulth objects. Microscopical samples of green paint from 82 Northwest Coast objects, as well as several pigment sources and mineral specimens, were analysed using Fourier transform infrared spectroscopy or X‐ray diffraction. Green earth was the most frequently identified green pigment, found in approximately 40% of the samples.     

THE BLUE ENAMELS IN THE BAROQUE DECORATIONS OF THE CHURCHES OF PALERMO,SICILY: FE2+‐COLOURED GLASSES FROM LIME KILNS*

Deep blue glasses coloured by octahedral Fe²⁺ cations are often reported as textbook examples of blue pigmentation. However, despite the possibility of laboratory synthesis under reducing conditions, to date there are no well‐reported occurrences of their production and use in the past. A thorough historical, ethnographic, mineralogical, and chemico‐physical investigation of the ‘smaltini di calcara’ from several baroque churches in Palermo, Sicily, has revealed that the blue enamels widely used for altar decorations in the 17th and 18th centuries are actually a unique case of ancient blue glasses pigmented by divalent iron cations in distorted octahedral coordination. This mixed‐alkali glass was accidentally produced under severely reducing conditions in the local kilns during production of lime.     

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.     

THE SECTILIA PANELS OF FARAGOLA (ASCOLI SATRIANO,SOUTHERN ITALY): A MULTI‐ANALYTICAL STUDY OF THE GREEN,MARBLED (GREEN AND YELLOW), BLUE AND BLACKISH GLASS SLABS

Analyses at the Cu–K, Fe–K and Mn–K edge were performed to study the green, marbled (green and yellow), blue and blackish (deep greyish olive green) glass slabs decorating three sectilia panels from the archaeological site of Faragola. Results indicate that all slabs were made by mixing siliceous sand with natron, sometimes probably mixed with small percentages of plant ash. Cu²⁺ and Pb antimonates should be responsible for the opaque green colours. The dark green and yellow portions of the marbled slabs are respectively comparable to the slabs comprising only one of these colours. Cu²⁺ together with Ca antimonates probably produced light blue slabs, whereas cobalt was used to produce dark blue slabs. We consider it possible that the abundance ratio of Fe²⁺/Fe³⁺ and the complex Fe³⁺S^2? would have an effect on the blackish slabs. The contribution of Mn cannot be ascertained even if it could have played a role in darkening glass colour. The comparison between the chemical composition of Faragola samples and several glass reference groups provided no conclusive evidence of provenance; whereas, the presence of a secondary local workshop can be hypothesized.     

PREHISTORIC WALL PAINTINGS: THE CASE OF THE DOMUS DE JANAS NECROPOLIS (SARDINIA,ITALY)*

The Domus de Janas (Home of the Fairies, or Home of the Witches) are Neolithic hypogea located throughout Sardinia (Italy) and decorated with red and black wall paintings. The objective of this study was to define the painting technique through the analytical characterization of the pigments and binding media. Samples of painting film from different graves have been examined by means of various analytical techniques. XRD, Raman and SEM–EDX analyses identified the red and black pigments respectively as red ochre rich in hematite and carbon black, while GC–MS analyses characterized the organic binder as egg.     

SCIENTIFIC ANALYSIS OF SEVENTH‐CENTURY GLASS FRAGMENTS FROM THE CRYPTA BALBI IN ROME*

Inductively coupled plasma emission spectroscopy, reflectance spectroscopy and X‐ray diffraction were used to study seventh‐century AD glass fragments from the Crypta Balbi in Rome. All the samples were found to be silica‐soda‐lime glasses. Iron determines the colour of blue‐green, green and yellow‐green transparent glasses; chemical composition suggests deliberate addition of iron and/or manganese in about half the samples. Copper was found as the main colourant in red, pale blue and blue‐green opaque fragments; elemental copper acts as an opacifier in red glass, and calcium antimonate in white, pale blue and blue‐green glasses. Detection of antimony in transparent fragments suggests recycling of opaque mosaic tesserae.