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Financial support: C2RMF, the LC2RMF UMR 171 CNRS, the Work package 5 of AUTHENTICO, the MRT – Ministére de la Culture et de la Communication, CNRS, the GdR 3174 CNRS “ChimArc” and Bruker AXS Microanalysis GmbH.
“AURUM – Authentication and analysis of gold work” proposed to get together international experts on the production of gold work, on the science-base techniques used for authentication of gold work and also representatives of law enforcement agencies that fight against illicit traffic of cultural heritage objects. The workshop comprised oral presentations – invited and regular – and poster contributions on the different aspects of ancient gold work production from the exploitation of gold ores to the manufacture of the gold objects and their conservation, restoration and trade, focusing also on the examination and analysis of the objects. More than 100 delegates from 28 countries attended the conference: Austria, Belgium, Brazil, Bulgaria, Canada, Colombia, Cyprus, Czech Republic, Egypt, France, Greece, Germany, Hungary, Iran, Ireland, Italy, Malta, Mexico, Netherland, Portugal, Romania, Russia, Spain, Tajikistan, Tunisia, United Kingdom and United States of America. During the three days four main sessions covered the different aspects of the gold work study: “Questions on the production and circulation of gold work”, “Scientific techniques of exam and analysis for gold work study”, “Gold mines and provenance” and “Gold jewellery, coinages and other artefacts - The Americas, Europe and Egypt”. In the last day a special session on forgery, trade and authentication was held as well as a round table on the same subject. A light lunch was served during the three days at the conference facilities and when the weather allowed it was possible to spend the lunch hour at the Carrousel gardens. In the first day after the opening remarks by Maria Filomena Guerra and Maria Luisa Vitobello, the morning was dedicated to the first part of the session on “Production and circulation of gold work”. Alicia Perea, an invited speaker, from Grupo de Investigacíon Arqueometal (Madrid) started with a communication entitled “Wands in the hand! Or Potter’s powers”. In this presentation several aspects of expertise and validation of gold works were focused, but a particular emphasis in two powerful wands was given: the electron beam microscope/microprobe and ion beam analysis, which includes PIXE, PIGE and RBS methods. The session continued with four communications about the production technology and the art of goldsmithing of several gold objects: the ancient Scythians (7th c. BC), the gold inlaid decoration from the early Sarmatian barrows (5th and 4th c. BC), the gilding of metals in the first millennium AD in the Germanic area and the filigree work of the “Tara” brooch (700 AD). The afternoon started with the invited speakers Pavlos Flourentzos and Maria Luisa Vitobello presenting a pilot study to help future attribution of a certain historical period production, authentication and anti-fraud measures. The study was focused on the excavated collection of jewellery from a Phoenician tomb at Kition (Cyprus). The afternoon proceeded with a communication about the gold jewellery study from the Koukova tumulus (5th c. BC) and from the necropolis of Duvanli (Bulgaria), then a technical study and methods of analysis applied to the filigree and granulation in the northern Levant in the 2nd millennium BC was presented and finally a very interesting communication entitled “The various interrogations and observations of an archaeologist-restorer working in situ, in gold objects” was performed. This was a very interactive approach that raised several questions to the audience, with clear case studies and questions that involved artefacts conservation and restoration. The second session (“Scientific techniques of exam and analysis for gold work study”) started with Guy Demortier, invited speaker, and an historical approach to the application of several non destructive techniques using external beams on the investigation of gold artefacts. The external beams that were experimented for the first time in the beginning of the 70’s are now frequently used for the characterisation of a wide selection of artefacts. A comparative approach to the use of PIXE, RBS and differential-PIXE was made, focusing on the good performance of differential-PIXE, which allows a better approach to the gold alloys study. The session continued with the presentation of other techniques: X-ray fluorescence (for the analysis of precious metals alloys), U-Th-He dating (to the detect forgeries among ancient gold objects), synchrotron radiation and induced X-ray fluorescence (characterization of ancient gold objects), µ-XRF, coupled SEM and external-beam PIXE, X-ray structural analysis of gold and silver and the application of a multi-analytical approach for the identification of technological process in ancient jewels. The presentation of Otto Eugster, invited speaker, “Detecting forgeries among ancient gold objects using the U-Th-He dating” was based on several studies that are being held by the author to over-come the fact that “the authentication of archaeological gold objects is a major problem once gold is probably the most difficult material for detecting modern forgeries, and there is no characteristic patina and sometimes it is impossible to unequivocally recognize forgeries based on manufacturing and decoration characteristics”. His work started in 1996 when he used the U-Th-He method to detect forgeries among gold objects. These elements (U and Th) are radioactive and are incorporated into the crystal lattice of the gold. Although a systematic and quantitative study of He, Th and He in a large number of ancient and modern gold objects were performed, a final conclusion was far from being achieved since the results presented a large gap of certainty and some inconclusive results. An always interesting topic is the application of synchrotron radiation to the study of art works. In this case, Martin Radtke (BAM) brought an application of “The use of synchrotron radiation and induced X-ray fluorescence for the characterization of ancient gold objects”. Synchrotron radiation (SR) is among the most versatile tools for characterisation of materials, combining a high spatial resolution with good detection limits – essential to the trace elements detection - and the possibility to work in normal atmosphere during the examination of large objects. In nearly all cases measurements with SR are non destructive. During this presentation several questions were raised. The first day ended with a welcome reception in the Louvre laboratories, where the participants had the opportunity to see the particle accelerator AGLAE (Accélérateur Grand Louvre pour l’Analyse Élémentaire), to take a look at the C2RMF facilities and to ask some questions about the work that is currently being done. The second day started with a new theme session “Gold mines and provenancing”. The invited speaker Béatrice Cauuet presented a study on the “Elites in the Antique industry: supervision of the production and the work in the goldmines of Gallia and Roman Dacia”. These goldmines reveal a high technical level and a well organised structure, where mining prospection took place before the opening of mines. The other presentations focused on several studies from different countries in different periods: “Gold mining and surviving technologies in French Guyana”, “Mineralogy and isotope signature of Au-Ag ores exploited during roman times en Alburnus Maior (Rosia Montana, Romania)”, “Gold in Georgia, Caucasus: analytical investigations of gold artefacts and native gold from the Caucasus and Transcaucasus”, “Gold deposits and the earliest gold objects from Italy” and “Gold alloys in early southeast Asia”. The poster session took place during the lunch break, with more than 20 posters being presented by the authors, covering some of the presented themes. After the lunch break, the 4th session “Gold jewellery, coinages and other artefacts - The Americas” started with Jean-François Bouchard (Archéologie des Amériques, UMR 8096 CNRS): “The pre-Hispanic jewellery from Tumaco and La Tolita: balance and perspectives”. The presentation focused on the scarce documentation regarding the artefacts recovered from these regions and the development of a project that will allow a better study due to the possibility of using a portable and non-destructive equipment. The objects from Tumaco (Colombia) and La Tolita (Equator) are among the most ancient metallurgical productions in South America and like many other objects from these countries they came to light by pillages, which make the study and tracing of these objects a hard task. Other communications came from Mexico, Peru and Panama. After the coffee break, the second part of the session started with “Europe and Egypt”. Two of the presentations were related to specific objects such as a necklace from Qurneh (Egypt) or the funeral golden masks, rings and sandals from Trebeniste (Macedonia), a broader study about the technological study of gold jewellery from the 17th dynasty in Egypt was also presented. “New finds for an old treasure”, focused on the archeometric study of the new gold objects found in the Phoenician sanctuary of El Carambolo (8th c. BC). A different approach to gold was made in two communications: “The illusion of gold: gold imitation in medieval mural paintings” and “Composition and technology of the gold leaf: the baroque altarpieces in Portuguese northwest. Three Porto altarpieces”. The second day ended with a group dinner in a central restaurant in Paris, where some typical specialties were served along with good wine and good talk. In the last day, a special session on forgery, trade and authentication took place. The morning began with three invited speakers: Pieter Meyers (“Authenticity studies of ancient gold artefacts”), Susan La Niece (“Fakes and public collections”) and Alberto Deregibus (“The Carabinieri Department for the Protection of Cultural Heritage and the forgery of metal works of art”) and ended with a round table on the same subject hosted by Thilo Rehren and Maria Luisa Vitobello and open to the audience. The round table was composed of several specialists from different parts of the world and from different areas – museums, police, universities and archaeological institutes. A special attention was given to the necessity to create good legal background concerning the trade and illegal commerce of artworks.
About the author: Ana Bidarra has a Degree in Conservation-Restoration and a Master Degree in GeoSciences on white structured pigments for restoration. Currently she is a PhD candidate researching the compositional and technological aspects of gold leaf from Portuguese baroque altarpieces. She works as conservator-restorer in private practice since 1999. ▲TOP
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