Landesamt für Denkmalpflege und Archäologie Sachsen-Anhalt
Landesmuseum für Vorgeschichte
You are here: Home > Nebra Sky Disc > Scientific analyses > Source of the raw materials > 
Deutsch | English

Source of the raw materials

Trace-element pattern of copper ores from the eastern Alps and from the Nebra disc.
Comparison of the trace-element pattern of copper ores from the eastern Alps (Mitterberg and Kitzbühl: shading) with that of the finds from Nebra (dots).
The Mitterberg.
The Mitterberg: Source of the copper in the Nebra hoard.
Lead isotope ratios of the Nebra finds and of a number of prehistoric copper bars from Kuchl in the Salzach valley, near the Mitterberg.
Lead isotope ratios of the Nebra finds and of a number of prehistoric copper bars from Kuchl in the Salzach valley, near the Mitterberg. These bars are generally agreed to be raw copper produced in prehistoric times on the Mitterberg.

To identify the source of copper, two methods are combined: the analysis of trace-elements and the analysis of lead isotopes. Every copper deposit contains a characteristic spectrum of subsidiary and trace-elements which are passed on into the metal when the ore is smelted. These are like a fingerprint which each deposit leaves in the metal. This method of analysis only works if no older metal has been re-used and raw materials from different sources have not been mixed, but it can usually be assumed that this did not occur in the early bronze age. The analysis of trace elements should only be of those elements which for the most part pass into the metal product in the smelting process and which are not significantly affected by the particular way this process is carried out. Many chalcophile trace- and subsidiary elements meet this condition.

The analysis of stable lead isotopes is the second important pillar in the characterisation of the source deposit. Lead is present as a subsidiary component in practically all copper deposits and it passes into the bronze alloy as an impurity in the copper. In many deposits, the lead has a different ratio of isotopes. Because lead isotopes then behave identically during the process of producing and working metal, the isotope ratios do not change as the ore is turned into metal. They therefore provide another 'fingerprint' of the deposit, in addition to the trace elements. It is true that this fingerprint is not unique for every deposit, but if there is no correspondence between the lead isotope ratio of an artefact and that of a given deposit, then that deposit can be securely ruled out as the source of the object's raw material. The ideal case is where only one possible deposit is left after the others are ruled out.

The results of the chemical and isotope analysis of the Sky Disc and the other Nebra finds were that the copper of both the disc and the other objects is very similar to that of the eastern Alps. There is an especially good correspondence with bars of raw copper that were found in the immediate vicinity of the famous prehistoric coppermine on the Mitterberg (Salzburger Land). That is no surprise. The area of the eastern Alps, with prehistoric mines still visible today, provided much of central Europe with raw copper in the early bronze age.

The gold, however, was for long thought to have come from Romania because of the silver contingent of 20% typical for that region. However, recent research including new geochemical methods and an extensive analysis of natural gold deposits all over Europe has shown that the gold used for the Sky Disc comes from Cornwall.