Greenstone artifacts in pre-Columbian Costa Rica: from raw material to local and interregional exchanges

Understanding the distribution pattern and relative abundance of the different greenstones used by pre-Columbian societies in the current territory of Costa Rica provides valuable insights into ancient exchange networks. This study examines the role of local and interregional exchange systems involving both locally sourced and allochthonous greenstones in the Greater Nicoya and the Central Caribbean regions. Non-invasive infrared spectroscopy was applied to identify the main mineral phases in 926 objects from 54 archaeological sites, and chemometric analyses were used to distinguish compositional groups and to visualize their spatial distribution. X-ray diffraction was additionally performed on five representative samples, one from each of the most frequent compositional groups, to complement the spectroscopic analysis. The results reveal that each region displays distinct patterns of greenstone use, reflecting differences in access to materials and participation in exchange networks. Data suggests that locally available minerals, such as serpentine, tremolite-actinolite, quartz and other siliceous rocks, were obtained through short-range procurement systems whereas allochthonous allochthonous jadeitite and albitite were involved in long-distance interregional exchange. These findings highlight the coexistence of regional and long-distance networks and demonstrate the key role of jadeite in linking distinct lithic traditions within Costa Rica and beyond.