Lasse Soerensen_New Discoveries Based on Brewer Carl Jacobsen | Carlsbergfondet
Til projektoversigt

New Discoveries Based on Brewer Carl Jacobsen’s Collection of Artefacts from the Neolithic and Bronze Age

Postdoc-stipendium i Danmark | 06/11/2017

This postdoctoral research generated new knowledge about the provenance and exchange of rare prestigious objects, such as jadeite axes, obsidian artefacts and cinnabar in the Aegean Neolithic and Bronze Age. The investigation centred on brewer Carl Jacobsen’s collection of stone artefacts, together with other prehistoric sites and quarrying places.

Probably the Toughest, Brightest and Sharpest Raw Materials from Aegean Prehistory


By Project Researcher, PhD Lasse Sørensen, The National Museum of Denmark

This postdoctoral research generated new knowledge about the provenance and exchange of rare prestigious objects, such as jadeite axes, obsidian artefacts and cinnabar in the Aegean Neolithic and Bronze Age. The investigation centred on brewer Carl Jacobsen’s collection of stone artefacts, together with other prehistoric sites and quarrying places. Firstly, the discovery of the earliest evidence of a systematic exploitation of jadeite in the world was apparently synchronic with the first farmers in Western Anatolia around the mid-seventh millennium BC. 

Secondly, the identification of the earliest proof for the exploitation of cinnabar in the Aegean area, in the mid-fourth millennium BC, was synchronic with the development of copper metallurgy and societies featuring socially hierarchies in the Aegean area. The third result was to separate the two obsidian sources of Adamas and Demenegaki on Melos by investigating their trace elements, which revealed a network of Early Bronze Age societies controlling procurement from the Adamas source. 

The results can be used to promote the unique Aegean quarry sites through future UNESCO World Heritage applications and leisure management. The project also created an international network of researchers, who are investigating the procurement of raw materials and how this exploitation changed whole societies in the Aegean area.

Jade is an old term for the rock consisting of jadeite (NaAlSi2O6) and nephrite (Ca2(Mg, Fe)5Si8O22(OH)2), which are two separate minerals; it is often green, but shows differences in its rarity, structure and chemistry. Jadeite is perfect for making axes, as it is a much tougher mineral than nephrite.


Probably the Finest Stone Collection

The empirical data in this project is based on brewer Carl Jacobsen’s archaeological collection of over 5,000 stone artefacts, together with the study of other prehistoric sites and quarrying localities. Carl Jacobsen bought the collection in 1887 from Athanias Rhousopoulos, an archaeology professor. The collection was built up in the period 1871-1884, with Rhousopoulos adding the provenance information about the artefacts (Sørensen & Rahmstorf 2016). 

The aim of the project was to produce a new synthesis of the interaction between prestigious objects of jadeite, cinnabar and obsidian, and new cultural and social developments in Aegean prehistory (Fig. 1).


Probably the Best Raw Materials

The largest known jadeite source in the Aegean is located on the Cycladic island of Syros. During sampling, several patinated flakes and preforms of considerable age were identified, demonstrating, for the first time, the presence of several knapping places around the large jadeite boulders (Fig. 1A). A previously unknown cinnabar source was discovered on the Karaburun peninsula in Western Turkey (Fig. 1B). 

Another survey was undertaken on the Cycladic island of Melos, with geological samples collected from the two most important Aegean obsidian sources of Adamas (Fig. 1C) and Demenegaki (Fig. 1D), in order to separate the two sources by investigating their trace elements.

Probably the Toughest Rock in the World

Several jadeite axes from Jacobsen’s collection were identified for the first time in the study of Aegean prehistory, using visual petrographic studies and spectroradiometry analysis, thus allowing comparison between larger geological jadeite and archaeological objects. The results indicated that the axes originated from jadeite sources in the Italian Alps and a local source on Syros (Pétrequin et al. 2012). 

These surprising results were tested by using X-Ray-Diffraction analysis on the same axes, which investigated their mineralogical composition. The results demonstrated that axes made of jadeite from the Italian Alps were of pure jadeite, whereas the axes of Syros jadeite were of a jadeite rich-rock mixed with albite and omphacite (Fig. 2). 

Another groundbreaking result was the discovery of jadeite axes originating from Syros, found at the site Cukurici Höyük in Western Anatolia. The axes were found in layers dated by 14C analysis to 6500 cal BC, making them the earliest evidence of jadeite exploitation in the world, which was contemporary with the first farmers in Western Anatolia (Sørensen et al. 2017). 

The axes originating from the Italian Alps came to the Aegean through an indirect exchange within a huge European network around 4500 cal BC, as these societies expressed their power through this access to prestigious raw materials (Fig. 2).


Cinnabar is a mercury sulfide mineral with a chemical composition of HgS, which makes it highly toxic. It is bright red in colour and was used as a luxury pigment by the Romans. The earliest use of cinnabar is dated to the eighth millennium BC at the site of Çatalhöyük in Turkey.

Probably the Brightest Pigment in the World

A stone stamp with traces of red pigment from Jacobsen’s collection was studied using x-ray fluorescence analysis (Fig. 3A). The results showed high mercury levels, which are characteristic of cinnabar (Fig. 3). An almost identical stamp with the same U-shaped signs was found at the site of Mikrothives near Volos, in layers dated to 3500 cal BC ( Adrymi-Sismani 2007) (Fig. 3B). 

It is therefore clear that the stamp from Jacobsen’s collection also dates to the mid-fourth millennium BC, meaning the cinnabar in the stamp is the earliest evidence of this pigment from Greece. The exploitation of cinnabar appears to be contemporary with the exchange of other prestigious objects in the mid-fourth millennium BC, in which the societies demonstrated their network alliances by having access to exotic raw materials.

Probably the Sharpest Stone in the World

One of the important research questions in obsidian studies is whether or not there was free access to or control of the Adamas and Demenegaki sources on Melos. Jacobsen’s collection plays a significant role in this discussion; it consisted of bullet-shaped cores, with blades knapped using pressure flaking which is a characteristic technological technique in the Early Bronze Age. 

Most of the assemblage in Jacobsen’s collection originated from a major Early Bronze Age workshop at the site of Phylakopi (Fig. 4A) and other contemporary sites on the Peloponnese, where the cores are smaller and thinner (Fig. 4B). The behaviour suggests that obsidian was a valued material on the Aegean mainland. 

However, if there was free access to the obsidian we would expect a mixture originating from both sources on Melos. In order to investigate this hypothesis, it was necessary to separate the two sources by combining the X-ray fluorescence method with principle component analysis of geological samples. 

The results documented some differences in the trace elements, thus making it possible to separate the two sources from each other (Fig. 4) (Ilsøe et al. 2017). The results showed large-scale exploitation of the Adamas source during the Early Bronze Age, which was controlled by the societies of Melos and the Peloponnese. Exchange within this network allowed some sites to flourish into more urbanised centres in the third millennium BC.   

Obsidian is a volcanic glass, which has a black or grey transparent glass structure. It was formed when silica-rich (65-75 % SiO2) magma cooled very quickly shortly after reaching the earth’s surface. Obsidian was a valued raw material, as it was the best material for making cutting tools.


Probably the Most Promising Perspectives

The results of this project demonstrate the unique geology and cultural history that is associated with the investigated quarry sites in the Aegean area, which can hopefully provide the foundations for future UNESCO World Heritage applications for the benefit of the general public. 

The project also helped create a network of international researchers working on the exploitation of prestigious raw materials and how this changed whole societies in the Aegean area. 

The generous grant from the Carlsberg Foundation also laid the foundations for future research applications, based on the many new research questions which have come to light in this postdoctoral research project.


Fig. 1. A. Jadeite boulders on Syros, Greece. B. Cinnabar source in Karaburun, Turkey. C. Adamas obsidian source on Melos, Greece. D. Demenegaki obsidian source on Melos, Greece. Map showing the locations of the investigated raw materials in the Aegean area within this project.

Fig. 2. Aegean Neolithic jadeite axes from Jacobsen’s coll. made of pure jadeite, originating from the Italian Alps (12, 14, 33 & 35) and a jadeite-rich rock from Syros (37, 41 & 53), based on petrographic and XRD analysis. Map showing the distribution of jadeite axes in the Mediterranean area.


Fig. 3. A. Stamp from Jacobsen’s coll. B. Stamp from Mikrothives. The Jacobsen stamp showed traces of red pigment. XRF analysis of the black line is from the back and the red line shows the red pigment, which had high mercury values showing that the pigment is cinnabar (drawing F. Oldenburger).

Fig. 4. Obsidian cores found at Phylakopi, Melos (A) and Kleonai, the Peloponnese (B) indicating extensive usage of cores on the mainland. Map of sites with analysed obsidian from Jacobsen’s collection. A PCA plot showing a first component split between Adamas and Demenegaki on Melos.

References

Adrymi-Sismani, V. 2007. Le site chalkolithique de Microthèbes au Carrefour du monde Égéen et des Balkans du nord. In: I. Galanaki, H. Tomas, Y. Galanakis &R. Laffineur (eds.): Between the Aegean and the Baltic Seas. Prehistory Across Borders. Proceedings of the International Conference, Bronze and Early Iron Age interconnections and Contemporary Developments between the Aegean and the Regions of the Balkan Peninsula, Central and Northern Europe. University of Zagreb, 11-14 April 2005. Aegaeum 27. Université de Liège, Histoire de l’art et archéologie de la Gréce antique, University at Austin, Liège and Austin: 73-79.

Ilsøe, P., Sørensen, L., Kjær, K., Toft, P., Ruter, A., Mavrogonatos, K. & Katerinopoulos, A. 2017.

How to obtain better cross lab comparability on pXRF analysis – demonstrated through two Melian sources of Adamas and Demenegaki. International Association for Obsidian Studies, December 2017.

Pétrequin, P., Cassen, S., Errera, M., Klassen, L., Sheridan, A. & Pétrequin, A-M. 2012.

JADE. Grandes haches alpines du Néolithique européen. Ve et IVe millénaires av J.-C. Tome 1 and 2. Presses universitaires de Franche-Comté et Centre de Recherche Archéologique de la Vallée de l‘Ain, Besançon. 

Sørensen, L. & Rahmstorf, L. 2016. Snyd ikke på vægten! – Nyt om gamle fund fra bronzealderen i Middelhavsområdet. Arbejdsmarken 2016: 158-169.  

Sørensen, L., Pétrequin, P., Pétrequin, A-M., Errera, M., Horejs, B. & Herbaut, F. 2017. Les limites sud-orientales des jades alpins (Grèce et Turquie). In: P. Pétrequin, E. Gauthier & A-M. Pétrequin (eds.):  JADE. Objets-signes et interprétations sociales des jades alpins dans l’Europe néolithique, tome 3. Centre de Recherche Archéologique de la Vallée de l’Ain. Presses universitaires de Franche-Comté: 491-520.   

Sørensen, L. 2012. Jacobsens ukendte samling af stensager fra den græske oldtid. Obsidian, økser, matricer, ansigtssten og andre sjældne oldsager. In: M. Moltesen, C. Fischer & T. Thunø (eds.): Buddha, Barok og Bryggeren. Carl Jacobsens ukendte samlinger. Meddelelser fra Ny Carlsberg Glyptotek, Ny serie nr. 14: 76-85.