A Highly Unusual Constituent in Roman Polychromy
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Keywords A highly unusual constituent Vanadium in Roman polychromy Egyptian blue Ancient polychromy Signe Buccarella Hedegaard1*, Alexandra Rodler1, Jørn Bredal-Jørgensen2, Sabine Klein3, and Cecilie Brøns1 Elemental and mineralogical 1 Ny Carlsberg Glyptotek, Denmark analyses 2 The Royal Danish Academy of Fine Arts, Schools of Architecture, Design and Conservation (KADK), Denmark 3 German Mining Museum, Germany * Corresponding author: [email protected], +45 29705455 Fig. 1 Fig. 2 The studied mould-made, polychrome VIL image of the terracotta relief (H 32 cm, W 35 cm) Campana relief showing from the NCG (Inv.no. IN 1708). The the distribution of red dot marks the sampling area for Egyptian blue. the cross-section in Figs. 4–7. Fig. 3 EDXRF mapping of Fig. 4 Micrograph (DIC) of a cross-section representing the pale, Fig. 5 SEM image of the cross-section in Fig. 4. Fig. 6 SEM-EDS image showing the Fig. 7 SEM-EDS image showing the one of the leaves showing greenish yellow paint on one of the leaves. The white circle The white circle marks a characteristic vana- distribution of V in the cross-section distribution of Pb in the cross-section the distribution of V. marks a characteristic vanadinite crystal formation. dinite crystal formation. depicted in Fig. 4. depicted in Fig. 4. Introduction Conclusion and METHODS AND MATERIALS It is a classic example of a mixed green colour. presence of vanadinite is generally used as indica- Avenues of further Ruby-red, stubby, hexagonal crystals characteristic tor of provenance. The relief was first examined using different pho- of lead vanadate or vanadinite (Pb (VO ) Cl) have During a demonstration of handheld research 5 4 3 tographic techniques incl. visible-induced lu- been identified in the matrix (Fig. 4). The SEM-EDS Judging from the few examples available for com- energy dispersive X-ray fluorescence minescence (VIL) imaging to identify any traces mapping and point analysis confirm that the pri- parison, it would seem that vanadinite often con- (HH-EDXRF) equipment, vanadium (V) • By means of ICP-SFMS, of Egyptian blue. Preliminary elemental analy- mary constituents in the yellow matrix are Pb, V, stitutes a contaminant rather than a main com- was unexpectedly detected in pale, PLM, and SEM-EDS, the ses were performed with handheld and portable Cl, and O which is in agreement with vanadinite ponent. In the case of the studied Campana relief, EDXRF (Bruker Tracer III-SD Bruker and XGLab (Figs. 5–7). The blue grains in the paint layer con- however, the concentration of vanadinite is higher greenish yellow and greenish blue investigated V compound has ELIO, respectively). Informed by this preliminary tain Si, Ca, and Cu in accordance with Egyptian than background levels indicating intentional use. paint layers on a so-called Campana been identified as vanadinite investigation, pigment layers were sampled for blue. relief from the antique collection of (Pb5(VO4)3Cl). major and trace element analyses (ICP-SFMS, Acknowledgements the Ny Carlsberg Glyptotek (NCG), Thermo Scientific ELEMENT XR), and for cross-sec- • The presence of the tions used for the characterisation of the micro- Discussion Copenhagen (Fig. 1). Campana reliefs stratigraphy of the painted decoration (PLM, Zeiss This investigation forms part of the research pro- synthetic pigment Egyptian are Roman terracotta reliefs produced Axioplan 2, 10×–100×; SEM-EDS, Hitachi S-3400N According to the instrumental and microscopic ject ‘Transmission and Transformation: Ancient between the 1st c. BC and the 2nd c. AD, blue (CaCuSi4O10) in the with Quantax 200 with XFlash 6|30 from Bruker), analyses, vanadinite forms a substantial part of Polychromy in an Architectural Context’. We would primarily in the area of Latium around vanadinite-containing paint respectively. the greenish hues of the polychromy. Vanadinite is like to thank Dr Lee Drake (Bruker) and Michele layers attests to their ancient a comparatively rare, secondary lead mineral oc- Gironda (XGLab) for XRF analyses which revealed the city of Rome. They were used as curring in the oxidised zone. Vanadinite is a highly the presence of vanadium and, thus, prompted the origin. exterior and interior wall decorations Results unusual constituent in Roman polychromy which investigation. We would also like to express our for temples, public and private could suggest modern intervention. However, the gratitude to the Carlsberg Foundation and the Ny • The concentration of The VIL image strongly indicates the presence of presence of Egyptian blue in the vanadinite-con- Carlsberg Glyptotek for their unstinting support. buildings. The exact provenance of vanadinite is high indicating Egyptian blue in the polychrome decoration. The taining paint layers testifies to their ancient ori- the examined relief is unknown. intentional use. blue background and the bluish rim at the bottom gin: knowledge of the production of Egyptian blue It was acquired by the NCG at an of the scene appear to contain very high concen- was lost sometime after the Roman era. It was first References trations of the pigment, whereas areas painted synthesised again in 1959, and it was therefore not auction in Rome in 1899. According to 1 A. Rouveret and Ph. Walter, Les stèles alexandrines du Musée du In our further research we will black, brownish yellow, and pale, greenish yellow available at the turn of the 20th century. the museum records, no mounting, Louvre : apport des analyses techniquesa l’histoire de la couleur dans investigate the polychromy seem to contain lower concentrations indicating la peinture hellénistique, Revue Archéologique, Nouvelle Série, Fasc. 1, pp. restauration or conservation has 216–220 (Published by: Presses Universitaires de France), 1998. of ancient artefacts, such as pigment mixtures (Fig. 2). Although vanadinite is a rare find, its occurrence been carried out on the relief since its in ancient polychromy has been documented be- 2 B. Bourgeois and Ph. Jockey, Le marbre, l’or et la couleur. Nouveaux other Campana reliefs, for the regards sur la polychromie de la sculpture hellénistique de Délos. In: S. acquisition. The XRF analyses showed elevated V counts in fore. Three cases are studies of polychrome sculp- Descamps-Lequime, Peinture et couleur dans le monde grec antique, Musée occurrence of vanadinite and the greenish paint layers on the leaves (Fig. 3) and ture in the Mediterranean area.1–2 Vanadinite has du Louvre, Paris, pp. 163–191, 2004. stem as well as in the bluish paint on the rim. also been identified in yellow ochre used for a 3 R. Piovesan, L. Maritan and J. Neguer, Characterising the unique related minerals e.g. mimetite polychrome sinopia under the Lod Mosaic, Israel: pigments and The chance discovery of V prompted Also, the polychromy in the said areas has a high polychrome, preparatory drawing (sinopia) under- painting technique, Journal of Archaeological Science 46, 68–74, 2014. (Pb5(AsO4)3Cl) and pyromorphite 3 further analyses. The investigation Pb content. These preliminary XRF results were neath the Roman mosaic of Lod, Israel. The min- 4 P. Holakooei, J.-F. de Lapérouse, M. Rugiadi and F. Carò, Early Islamic (Pb5(PO4)3Cl). confirmed by major and trace element analyses. eral has also been identified in association with pigments at Nishapur, north-eastern Iran: studies on the painted is aimed at characterising the V fragments preserved at The Metropolitan Museum of Art, Archaeological wulfenite on Early Islamic painted fragments from and Anthropological Sciences, 1–21, 2016a. compound addressing questions of Consulting the cross-sections, it is apparent that Nishapur, NE Iran4 and on Late Sasanian painted 5 P. Holakooei, A.H. Karimy, A. Hasanpour and O. Oudbashi, Micro-Raman originality and intentionality. the paint layer is applied directly onto the terra- stucco in Ramavand, W Iran.5 In the two latter spectroscopy in the identification of wulfenite and vanadinite in a cotta substrate. The paint consists of a pale yellow cases the exploitation of nearby mineral resources Sasanian painted stucco fragment of the Ghaleh Guri in Ramavand, western Iran, Spectrochimica Acta Part A:Molecular and Biomolecular matrix with red and angular, light blue inclusions. is indicated as the most likely provenance and the Spectroscopy 169, 169–174, 2016b. Session 12a, P-2320 Geochemistry for the understanding of cultural heritage.