Precious metals in gossanous waste rocks from the Iberian Pyrite Belt
van Veen, E.
Reason for embargo
The Iberian Pyrite Belt (IPB) is one of the largest (if not the largest) of the world’s massive sulphide provinces. Since the Chalcolithic era, gossans formed from the massive sulphide mineralisations have been worked for copper, silver and gold, and consequently many historic mine sites have abandoned dumps of gossanous material. The aims of this study are to determine the mineralogical hosts of precious metals (Au, Ag) and environmentally significant elements (As, Ba, Bi, Cu, Hg, Mo, Sb, Se, Pb, Zn) in gossanous waste rocks from historic dumps, using geochemical, optical, SEM–MLA and laser ablation techniques. Results demonstrate that the precious metals are contained as inclusions of electrum, Au and Ag–Hg halides commonly within iron oxides and hydroxides. At least part of the inclusion surfaces are exposed and thus may be amenable to processing, however, the encapsulated nature of the precious metal inclusions along with their small size could make mineral processing difficult. In addition, the As, Bi and Pb enrichment of iron oxides and the presence of Ag–Hg halides may require suitable and safe storage of processing wastes. The study indicates that a solid knowledge of the mineralogical siting of precious metals and environmentally significant elements in gossanous waste rocks is required to assess processability in the move towards sustainable mineral resource development.
The authors would like to acknowledge the support of CRC ORE, established and supported by the Australian Government’s Cooperative Research Centres Programme. The analytical facilities at the Central Science Laboratory, University of Tasmania, were used for SEM–MLA measurements in this project. Analytical facilities at CODES (ARC Centre of Excellence in Ore Deposits), were used for LA-ICPMS measurements and some XRD measurements. Comments and suggestions from two anonymous reviewers were much appreciated.
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.
Vol. 87 (1), pp. 45–53