Post-Doctoral Fellowship: An Interview with Verena Leusch
The pieces of jewelry that archaeologist Verena Leusch are focusing her attention on have two things in common: they are made of gold, and most of them are several thousand years old. With a post-doctoral fellowship from the AXA Research Fund, this expert in pre- and early history is examining another 150 gold pieces. The techniques she uses enable her not only to know whether the jewelry is authentic, but also to reveal other fascinating secrets.
In the context of this project, you are analyzing some 150 pieces of jewelry. How do you carry out your research?
Verena Leusch: I examine the artifacts taking into account three different aspects: their form, how they were made, and their chemical composition. Just based on the way they were shaped, or their typology and surface structures, we can draw conclusions about when they were made. The chemical analysis is the most complex part of my work and it enables me to draw further conclusions about the authenticity of the objects.
Could you describe this part of your work in more detail?
Chemical analysis gives me a very precise description of the materials used. I start with what is known as X-ray fluorescence (XRF) analysis. This technique enables me to determine what alloys are used, in particular the primary elements of gold, silver and copper. The next step is to do a trace element analysis, which is really the core of my work. I use a procedure called mass spectrometry. In addition to the main components of gold alloys, it also analyzes the minutest amount of trace elements, which helps me to arrive at a more precise description of the gold that has been used. In the context of this project, this research should lead to other findings about how modern gold-based materials can be distinguished from ancient materials used in making gold artifacts.
Why do alarm bells go off for you when a surface is composed of pure gold?
Gold purity can be a sign of counterfeit. In nature, gold does not exist in a pure form. It always contains elements of some other natural alloys, most often several percentage points of silver, and also copper, in smaller amounts. So as a rule, the gold that has been obtained must first be artificially refined, to get a gold content of over 99 percent. As far as we know, this technique for artificially raising the gold purity was only discovered in the 6th century BC. So when we see gold artifacts that date from a period prior to the 6th century BC and that test for a gold purity higher than 99%, it raises the question as to whether the dating is accurate, or in general, how this alloy composition could have come about. If, in addition to an exceptionally high level of gold purity, we are hardly able to detect any other elements using our highly reliable detection methods, the possibility of a modern counterfeit must be considered. As my Ph.D. supervisor, Prof. Dr. Ernst Pernicka has recently demonstrated, the production of such high purity gold can only be possible using modern chemical or electrolytic techniques, and finding such evidence is a clue that the piece is a modern production no more than 150 years old.
So the analysis of the chemical components can provide decisive clues for the detection of counterfeits and can avoid inaccurate classification of artifacts.
For a long time now you have been conducting research on the subject of gold. In your current research project, which you are conducting in collaboration with the Reiss Engelhorn Museum, did you have to overcome any particular challenges?
The main difference compared with my previous work is that my current research project deals with objects that, as a rule, have not been placed precisely in a context. In other words, they do not come from well-documented archaeological digs and they are very difficult, as isolated objects, to place in an exact cultural context. Frequently, their fundamental historical authenticity has not even been verified accurately. Therefore, my way of going about this research is different from the way I have worked in the past, as I cannot assume at the outset any fundamental authenticity of the objects, as was the case in my dissertation.
What happens to the findings you have gained through your research?
All the data that have been compiled are initially collected in a databank for each studied object. These data are then discussed and evaluated in partnership with the curators. The goal is first to provide additional information for the various collections about their objects, and to assess their authenticity. Subsequently, these data and evaluations will also be published so that other researchers can have access to the knowledge gained. For my current project, I also have access to literature that deals with analyzing the authenticity of gold artifacts. As an example, I can cite the work done by colleagues from the British Museum in London. In general, the systematic data cataloging of any future work dealing with the authenticity of gold objects will be useful. Finally, museums are prime beneficiaries of this research, but so are organizations such as UNESCO and Interpol, which are grappling with investigations of illegal trade in cultural artifacts.
Apart from the authenticity of the pieces of jewelry, what makes such a research project particularly relevant today?
Analyzing authenticity is not just particularly relevant today. It always has to be kept on the cutting edge, and this project can make a small contribution to this end. Above all, in recent years, we have seen that many ancient works of art have disappeared with the plundering of museums, for example in Iraq and in Egypt. These works are sucked into the black market where they are traded. UNESCO regularly reports on this illegal trafficking and tries to develop measures to keep it contained. Trafficking in ancient cultural artifacts is potentially extremely profitable, and this also creates conditions that result in more counterfeits being put into circulation. Once an artifact turns up in circulation, the question is always raised as to whether it is an original or a replica. Here a careful authentication of the artifact is especially important, so chemical analysis becomes increasingly relevant all the time.
However, such research is also valuable from another cultural-historical perspective. Every work tells a story: about the epoch in which it was produced, and about the people who made it. We need to know how to interpret these signs: in this way, the superficial clues on a bracelet have something to tell us about the kind of tools the artist used, and what techniques had been mastered to make the object. In a broader context, conclusions can be drawn about how people lived together and about cultural history. A precise look at the artifacts can help us to correct false impressions about the past. Therein lies a very unique and exceptional value.