Copper in ordinary chondrites: Proxies for resource potential of asteroids and constraints for minimum-invasive and economically efficient exploitation

Abstract

Ordinary chondrites originate from S-type asteroids. These meteorites can be used for laboratory studies that further our understanding of the geological conditions on asteroids, including assessment of their resource potential. Asteroids have since long been considered to host significant resources of siderophilic elements such as Fe, Ni, Co, Cu, that could be exploited in situ. However bulk rock mining would be largely impractical. In this paper, we report on abundance and mineral occurrences of copper in H chondrites, identify Cu carrier minerals and interpret their distribution in the context of processes that must have affected parent bodies. This leads us to suggestion that some parts of S-type asteroids contain Cu in a form and amount that would satisfy requirements of potentially economically and environmentally more efficient exploitation.Parent bodies of chondrites contain 70–100 ​ppm of Cu in bulk and this is mainly contained in Fe,Ni-alloy. However, parts of asteroids that were affected by shock processes and post-shock thermal annealing may host Cu that exsolved from primary alloy and forms native, pure-Cu grains. Up to 50 ​ppm of Cu may be present in such phase in these parts of asteroids. Grains of native copper can be extracted from the host rock via mechanical mineral processing methods, releasing need of extensive chemical leaching. This makes potential exploitation more targeted and less destructive for the local environment.A characteristic feature associated with enrichment in native Cu in chondrites is presence of shock-darkened zones. Therefore, we suggest that shock-darkened asteroids are potentially best sites for Cu exploitation.