Investigating Pre-Columbian Gold and Copper in Costa Rica – Ores, Mines and Artefact Production

Abstract

The wealth of pre-Columbian gold, copper and guanín (an alloy consisting mainly of gold and copper; also tumbaga) artwork of Costa  Rica suggests that exploitation of its abundant ore deposits goes back way before the Spanish conquest. The name of Costa Rica itself in fact alludes to the large numbers of golden metal objects worn by the indigenous peoples upon arrival of the conquistadors. Up to now, however, very little is known about pre-Columbian mining in the country or the raw material provenance of these artefacts.
In a transdisciplinary project, we aim to reconstruct the metallurgical process chain by combining (mining) archaeological research with geochemical analysis of local ores and metal artefacts using a combination of different techniques. We identified four major gold and  copper districts with different mineralisation types, which are the focus of our fieldwork-based research. They are surveyed for  potential signs of pre-Columbian metal production and sampled for ores and their processing remains. On the other side of the process chain, we focus on the metal artefacts in museum collections. They are systematically registered in a database, which serves as a basis to identify correlations with the geochemical signatures of the artefacts, and to retrace potential links to possible areas of origin or different workshops. Once the necessary basic data have been collected, we will focus on economic and socio-cultural aspects of  metal production and circulation. The results from Costa Rica will be put into perspective of New World early metallurgy and can provide a starting point for future research between Mesoamerica and the Isthmo-Colombian region.