Matthias Heinzel1, Eschly Kluge2, Dorothee Kemper3, Burkhard Schillinger4 and Christian Stieghorst4
1Leibniz Zentrum für Archäologie
2Institut für Kernphysik (IKP), Universität zu Köln
3Deutscher Verein für Kunstwissenschaft e.V. Berlin
4Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München
During my time as freelance conservator for the state archaeology in Mainz, Germany, I often received ‘fresh’ interesting objects from current excavations in Mainz and the surrounding area. Most of these came from the Roman Period and the Middle Ages. One late afternoon during the excavation campaign 2008-2009, my colleague Klaus Soukoup brought me a small, severely corroded, but interesting looking metal object from an excavation he was working on in the historic district of Mainz. The excavation had taken place in the courtyard of a baroque palace. The object was found in a trash pit. The pit mostly contained pottery from the middle of the 14th century. But, this curious piece of corroded metal was also found. Over the following months I restored the small object, slowly uncovering that it was probably a pendant in the shape of a quatrefoil. My colleague, Stephan Patscher from the Leibniz Zentrum für Archäologie (LEIZA, before 2023 known as RGZM), initially made some radiographs of the object. The X-rays revealed the exact shape of the quatrefoil and some figural representations: we did indeed have a pendant from the Middle Ages. See Figure 20.
When I began a new job at LEIZA in 2016, I was able to explore the pendant in more detail. On a conference in Hildesheim (Lower Saxony) in 2017, I got to know art historian Dorothee Kemper. When I showed her photos of the pendant, she was able to classify it clearly in terms of art history. She also directly recognized the function as a relic pendant and encouraged me to look into it more closely.
Figure 20. Pendant before restoration and radiograph of side and front. Photograph by M. Heinzel, Radiographs by S. Patscher, LEIZA.
Figure 21. Front, side and reverse of the pendant after restoration. Photographs by S. Steidl, LEIZA.
Also known as a phylacterion, the pendant is quatrefoil in shape with a central square. It is made of gilded copper. An eyelet is visible at the top, suggesting that the object could have been worn around the neck on a ribbon or chain. It consists of two parts: the container and the closure. These two parts are held together by a visible rivet. Front and back are enameled using the émail champlevé technique and are decorated with several figural representations. See Figure 21. All figures carry a nimbus and are raised from the background, engraved and gilded. The background fields, halos, the frame of the central field and the internal drawings of the figures are all enameled. The colour spectrum of the enameled areas is quite narrow and varies between the front and back. The representations in the upper semicircle segment of both sides (where the riveting of the two components is located) were constructed taking into consideration the placement of the rivet, so the figures on the front and back tilt their heads to the right, thereby providing a place for the rivet. The side section of the pendant is cross-hatched (with the exception of the closure). The lozenges are gilded, and the lines are enameled. The pendant has the following dimensions: length 67mm (with bail), 57mm without the bail; width 57mm and thickness 11-12mm. The handle is about 10 mm in diameter. The object’s total mass is 70.5g.
Two different techniques were applied for the analysis of the pendant’s surface. Elemental analysis was done using μ-XRF. Results found that the substrate metal is copper (Cu 99.2% / Pb 0.4% / Ag 0.2% / Sn 0.2%) and the gilding is fire-gilding, evidenced by a high content of mercury (Au 83% / Hg 17%). The glass and pigments of the enamels were investigated using Raman spectroscopy. There are four different opaque enamel colours on the object: white, blue, green and turquoise green. All colours were made from a soda glass; the green glass is a leaded glass. The other three enamel colours contain lead with a small percent of lead oxide (PbO). Calcium antimonate was found to be the opacifying agent in the opaque enamels (white, blue, and turquoise). The antimony content of the green glass is too low to create an opaque enamel, but the colours of the other enamels were created as follows: blue by copper and cobalt, green by copper and lead and finally turquoise by copper.
After the restoration, it was clear that the pendant still contains small reliquary packages of some sort. To visualize the contents, neutron tomography was performed at the Research Neutron Source Heinz Maier-Leibnitz (FRM II), Technical University of Munich in Garching. A combination of a position-sensitive Prompt Gamma-ray Neutron Activation Analysis and Neutron Tomography (PGAI-NT) was used to reveal the reliquary’s internal structures and content. It was surprising to see that the carbonaceous content was revealed to have five intact reliquary packages. See Figure 22.
Figure 22. Neutron tomography of the pendant with five reliquary packages. Neutrontomography by B. Schillinger, FRM II.
I was more than happy to have a look inside the pendant without having the possibility to open it! The small packages consist of tiny particles of bone covered by textile and wrapped by a thin thread to keep them together. Usually, such packages are labelled with a specific saint’s name written on attached parchment strips known as authentic or cedula. However, in the present case, no signs of parchment strips can be found in the NT images. Thanks to the neutron imaging, the exact measurements of the textiles and bones could be taken by Eschly Kluge. See Figure 23. I would never have expected that such a thing could be possible. Through the PGAI-NT, the content of the pendant could be determined by elemental analysis. Six of 29 positions stand out. See Figure 24. In comparison to reference positions and surface materials, these positions contain significant abundances of hydrogen, calcium, and potassium. See Figure 25.
Figure 23. Detailed structures of the reliquary packages (textile and splinters) on a NT-slice. Neutrontomography by B. Schillinger, FRM II.
Figure 24. Reliquary PGAI-NT positions with 29 measurement points. Neutrontomography by B. Schillinger, FRM II.
Figure 25. PGAI-NT for the elements a) calcium, b) hydrogen and c) potassium/iron. Neutrontomography by B. Schillinger, FRM II.
The additional hydrogen content along the vertical axis supports the presence of biological material. The relatively high hydrogen content at the closure fits well with the identification of beeswax within this area. The increased calcium content along the vertical axis in combination with the amounts of hydrogen is a strong indication for the presence of bone. Some of the hydrogen likely also stems from the textiles. Based on PGAI-NT’s structural and elemental analysis combination, it is therefore extremely likely that the objects within bags 2, 4 and 5 are indeed bone material. The plate in container 2 further identifies as bone by the visually prominent spongy structures in the cortex tissue. The same certainty cannot be applied for the contents of bags 1 and 3, so these objects can simply be labelled as ‘fragments’. When it comes to the components of the pendant’s frontal and back plates, it is of no surprise that the results of the PGAA coincide with those of the X-ray fluorescence spectroscopy.
Furthermore, with the aid of infrared spectroscopy, a small sample of wax from the area of the closing part was indeed identified as beeswax. The analysis of a small fragment of fibre (which had survived in the pendant’s suspension eyelet) revealed that it was made of silk. All in all, we were ecstatic to get such a great deal of information about the components of this pendant through the use of different – and importantly – non-destructive methods!
For example, here are the details of just one of the five reliquary packages numbered along the vertical symmetry axis of the pendant from top to bottom:
1. Packaging: a very fine, lose lying outer textile (vertical and horizontal thread spacing of 0.33mm and 0.26mm; 2. vertical and horizontal thread densities of 30 and 39 per cm) with an estimated spatial volume of about 2cm; 3 encloses a relatively tight-fitting and coarse-threaded textile, whose nominal thread characteristics could not be determined. Contents: an irregular tetrahedral-like splinter of osseus material with maximum extents of 7.2mm to 5.3mm to 5.1mm.
An exact description of the manufacturing technique of the pendant was possible following the NT. See Figure 26.
Figure 26. Exploded drawing of the construction components. Drawing by V. Kassühlke, LEIZA.
This quatrefoil-shaped reliquary pendant dates to the last third of the 12th century and most likely comes from a workshop in Hildesheim, Lower Saxony. This is supported by the general shape of the item as well as other characteristics which can be found in comparable objects from the region. The object presented here is one of only four phylacteria of this type known today from the Hildesheim workshop; the other three are currently located in museums in Halberstadt, Boston, and Rome. The artefact was made to contain relic particles. After completion of the container, the reliquary packages were inserted, and the reliquary was tightly closed. Through different examination methods, the various materials used could be determined. The pendant was made of gilded copper and enameled using the émail champlevé technique. The four different enamel colours were successfully analysed and determined by μ-XRF and Raman spectroscopy. The examination of a thread fragment from the area of the suspension eyelet revealed silk. Importantly, this is also the first evidence for the material on which such pendants were most likely carried. A sample of a waxy substance was identified as beeswax using infrared spectroscopy. Neutron tomography was used to visualize the contents of five relic packages. In addition, measurements of the textiles and individual splinters could be taken. The material thickness of the metal parts and the enamel fields were also determined in this way. With the additional PS-PGAA, the content could also be determined by elemental analyses.
This reliquary pendant is a rare example of such an object from a controlled excavation. It was only through the collaboration of archaeologists, art historians, chemists, neutron researchers, a nuclear physicist, restorers and goldsmiths that it was possible to arrive at these detailed results. Although this short article describes a fruitful interdisciplinary research endeavor concentrating on an exciting, once-in-a-lifetime find, one question that has not been answered after 500 hours of restoration and six years of research is why. Why was it thrown away? Was the discard intentional? Was it by mistake? Both scenarios are of course possible. Was the object hidden in a pot and thrown away without knowledge of what the pot contained? Or, consider a more entertaining option—perhaps our reliquary was lost in the dump while the archbishop of Mainz was taking a…well… Regardless, what we do know is that this reliquary is a further example of the surprising treasures that can be unearthed in old rubbish pits.
Bibliography and further reading
Brepohl, Erhard 1999. Theophilus Presbyter und das mittelalterliche Handwerk, Buch III, Kap. LIIII, 136-140. Köln
- Heinzel, M., Kluge, E., Kemper, D., Schillinger, B., Stieghorst, C. 2022. New discovery of a 12th century enameled reliquary pendant – element analysis and content visualization, using Prompt Gamma Activation Analysis and Neutron Tomography (PGAI-NT). Metal 2022 – Proceedings of the Interim Meeting of the ICOM-CC Metals Working Group. Edited by Paul Mardikian, Lisa Näsänen and Ari Arponen, 184-191. Helsinki
- Kemper, Dorothee 2020. Die Hildesheimer Emailarbeiten des 12. und 13. Jahrhunderts. Regensburg
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