DOMUS AUREA,THE ‘SALA DELLE MASCHERE’: CHEMICAL AND SPECTROSCOPIC INVESTIGATIONS ON THE FRESCO PAINTINGS

In this paper, data collected from the wall fresco paintings of room 114, called the ‘Sala delle maschere’, of the Domus Aurea in Rome is analysed. The chemical composition of the efflorescence is investigated by infrared spectroscopy. The colour palette is determined by means of EDXRF, Raman spectroscopy and visible reflectance spectroscopy. EDXRF has allowed an extensive mapping of the elements present in the pigments and plaster; whilst in‐situ Raman spectroscopy has been determinant for attributing the molecular composition of the pigments in a number of doubtful cases. Most pigments identified are typical of Imperial Roman fresco paintings (first to fourth centuries AD) ( Ward‐Perkins 1981 ); more interestingly, we found evidence of fragments painted with Egyptian blue, which was normally used mostly in official rooms.     

ROMANO‐EGYPTIAN RED LEAD PIGMENT: A SUBSIDIARY COMMODITY OF SPANISH SILVER MINING AND REFINEMENT*

Samples of red pigment from a group of seven Roman‐period Egyptian mummies, known as red‐shroud mummies, are investigated. Elemental analysis by inductively coupled plasma time‐of‐flight mass spectrometry (ICP–TOFMS) shows that the samples contain mostly Pb (83–92% by weight), along with 0.2–2.0% Sn. All of the samples are found to have similar trace element distributions when normalized to the continental crust, suggesting that they share a common geological origin. Lead isotope ratios are found to match the mixed lead sources typically associated with Rio Tinto, Spain – a site extensively mined for silver during the first century ad . Raman microspectroscopy identifies the major phase of each sample to be red lead (Pb₃O₄) with a minor phase of lead tin oxide (Pb₂SnO₄). Lead tin oxide does not occur naturally, and its incidental occurrence within the sample indicates that the material was heated under oxidative conditions at temperatures in excess of 650°C. In archaeological contexts, the high‐temperature oxidative treatment of lead is typically associated with metallurgical refinement processes such as cupellation. Based on this evidence, it is argued that the pigment was produced out of litharge associated with silver cupellation at the Rio Tinto site.     

A SPECTROSCOPIC INVESTIGATION OF PIGMENT AND CERAMIC SAMPLES FROM COPÁN,HONDURAS*

A combination of micro‐Raman spectroscopy, micro‐infrared spectroscopy and SEM–EDX was employed to characterize decorative pigments on Classic Maya ceramics from Copán, Honduras. Variation in red paint mixtures was correlated with changing ceramic types and improvements in process and firing techniques. We have confirmed the use of specular hematite on Coner ceramics by the difference in intensities of Raman bands. Different compositions of brown paint were correlated with imported and local wares. The carbon‐iron composition of the ceramic type, Surlo Brown, was confirmed. By combining micro‐Raman analysis with micro‐ATR infrared and SEM–EDX, we have achieved a more comprehensive characterization of the paint mixtures. These spectroscopic techniques can be used non‐destructively on raw samples as a rapid confirmation of ceramic type.     

ICP–MS ANALYSIS OF GLASS FRAGMENTS OF PARTHIAN AND SASANIAN EPOCH FROM SELEUCIA AND VEH ARDAŠ?R (CENTRAL IRAQ)*

Forty‐one glass fragments were analysed by inductively coupled plasma – mass spectrometry, determining 40 major, minor and trace elements, including rare earth elements. The fragments came from excavations carried out at the archaeological sites of Seleucia and Veh Arda??r in modern Iraq, and were dated to the Parthian and Sasanian epochs. Analytical data indicate that all the samples are silica–soda–lime glasses. Magnesium and potassium oxide contents below 1% suggest that eight out of nine glasses from Seleucia, dating from between the first and the third century ad , could have been obtained by use of an evaporite as a flux; the same conclusion can be drawn for some of the Sasanian glasses dating from the fourth and fifth centuries ad . The other glasses from Veh Arda??r, as well as the remaining sample from Seleucia, are characterized by higher contents of magnesium and potassium, which suggests recourse to plant ash; different magnesium and phosphorus contents allow one to separate these samples into two main groups, pointing to the use of different kinds of plant ash. Aluminium and calcium contents, together with trace element data, may indicate that different sands were used for preparing glasses of different composition. Samples from Seleucia and Veh Arda??r are mainly blue–green and green to yellow–green, respectively; iron and manganese contents suggest that the furnace atmosphere was mainly responsible for the development of these hues.     

COMPOSITION AND ORIGIN OF IAPYGIAN POTTERY FROM ROCA VECCHIA,ITALY

We have studied 35 samples of fragments of ceramic containers dated between the eleventh and the eighth centuries BC, found at the archaeological site of Roca Vecchia, some 20 km from Lecce along the Adriatic (Salentine) coastline. Analysis of the elemental composition of the finds has been performed by means of atomic emission spectroscopy in plasma and the results obtained have been treated with diverse multivariate statistical techniques. Except for some minor differences, the statistical analysis confirms the grouping structures indicated by typological and stylistic evaluations of the samples, in accordance with the validity of the above methods.     

FIRING ANALYSIS OF SOUTH-EASTERN MISSOURI INDIAN POTTERY USING IRON MÖSSBAUER SPECTROSCOPY*

The Mössbauer spectra of prehistoric pottery and clay from the Malden Plain of south-eastern Missouri, USA, were examined. The pottery dates from AD 500 to 1400. The earlier sherds were tempered with sand and the later ones with shell. The sherds and clay contain a mixture of illite, smectite, and kaolinite. Most samples of clay and sherds contained both ferric and ferrous species. The spectral parameters for the ferric species were %DLE_Q～0. 7—1.1 mms^-1 and δ～0.0–0.3 mms^-1 for the ferrous species, ΔE_Q～2.1–2.7mms^-1 and δ～0.7–1.0mms^-1. The ferric to ferrous ratio is more accurately determined from the spectra than from consideration of the colour or the firing core of the sherds, which are not always related to the iron species ratio. Differences among sherds in the ferrous ΔE_Q can be related to original temperature of heating but with low precision.     

TEPHRA SAMPLES FROM MOCHLOS AND THEIR CHRONOLOGICAL IMPLICATION FOR NEOPALATIAL CRETE

Five deposits of Santorini tephra have been found in the excavations currently under way at the site of Mochlos which lies on the north coast of Crete about 140 km to the south of Santorini. This paper provides refractive index and trace element analyses for the largest of these deposits, examines the stratigraphy of all five deposits, and notes the chronological implication of this stratigraphy for the Late Minoan IB period, the floruit of Minoan civilization.     

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPIC AND ISOTOPIC ANALYSIS OF CARBONIZED RESIDUES FROM SUBARCTIC CANADIAN PREHISTORIC POTTERY

Late prehistoric pottery is found in abundance at archaeological sites around Southern Indian Lake. Black residues, found on the two dominant vessel forms, flat plates and round pots, are presumed to be the remains of prehistoric meals. ¹³C cross-polarization magic-angle-spinning nuclear magnetic resonance spectroscopy (CPMAS NMR) and¹³C and¹⁵ N isotopic ratios and C/N ratios are used to reconstruct prehistoric diet and to shed light on possible uses for the plates. Samples of foods were cooked in clay pots, on a wood fire, to simulate the conditions of burning that could have produced the residue. Decomposition of carbohydrates, protein, and fat during cooking is studied with ¹³C CPMAS NMR, and the effect of cooking on isotopic and C/N ratios documented. Predominantly fish and fat were cooked in the pots, whereas the residues from plates contain a greater proportion of fat and could have been used as frying pans or possibly as fat-burning lamps placed on the ashes of a wood fire.     

OBSIDIAN IN THE MEDITERRANEAN AND THE NEAR EAST: A PROVENANCING SUCCESS STORY

Obsidian provenancing studies comprise one of the most productive and successful research programmes of archaeological science. Obsidian characterization has been successful because workable obsidian is homogeneous on a small scale, analysable by a large number of methods, and is restricted to a small number of mainly readily distinguishable geological sources. Analytical, dating, source, and trade studies within the western Mediterranean, central and eastern Europe, the Aegean, and Anatolia and the Near East during the last 30 years or so are reviewed. Research has shown that distributions are mainly separate in the four regions examined, and that obsidian was traded up to 900km in the prehistoric period. Publications on obsidian in the areas under review reached a peak of frequency in the later 1970s and 1980s, but have now decreased in number. This may reflect changing fashions in archaeometric studies, and a current lack of routine application of the provenancing methods developed.