Precise and Accurate Analysis of Gold Alloys: Varna, the Earliest Gold of Mankind—A Case Study

Abstract

During the last decade an analytical routine was established that allows determining the composition of gold artifacts for major and trace elements by LA-ICP-MS. This micro-invasive method has proven highly suitable for detailed characterization of prehistoric gold in order to investigate its chaıˆne ope´ratoire. At the CEZA laboratory (Mannheim, Germany) two different analytical set-ups were developed that yielded accurate and precise results for determining the whole range of matrix components within the gold. They are based upon different calibration strategies— liquid calibration with the ICP-MS operating under wet plasma conditions, and external calibration by solid standard reference materials with the ICP-MS operating under dry plasma conditions—that enable flexible adjustment according to different sample properties. They are described and compared within this paper. An archaeological case study of gold finds from the chalcolithic cemetery of Varna (Bulgaria) demonstrates the applicability of the analytical methods for archaeome- tallurgical studies. These analyses yielded valuable information for defin- ing and comparing groups of gold artifacts that allude to their distribution within the burial site. However, the comparison of artifact gold with geological gold samples proved problematic, and clear relations between artefacts and specific gold occurrences are difficult to demonstrate