Soil & Water Res., X:X | DOI: 10.17221/143/2025-SWR

Silver geochemistry and isotope systematics in Ag-rich mine tailings from NamibiaOriginal Paper

Aleš Vaněk ORCID...1, Maria Vaňková ORCID...2, Vojtěch Ettler ORCID...2, Martin Mihaljevič ORCID...2, Bohdan Kříbek ORCID...3, Petra Vokurková ORCID...1, Tereza Zádorová ORCID...1, Vít Penížek ORCID...1, Ondra Sracek ORCID...4, Benjamin Mapani ORCID...5
1 Department of Soil Science and Soil Protection, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic
2 Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University, Prague, Czech Republic
3 Czech Geological Survey, Prague, Czech Republic
4 Department of Geology, Faculty of Science, Palacký University, Olomouc, Czech Republic
5 Namibia University of Science and Technology, Faculty of Engineering and Built Environment, Windhoek, Namibia

In this study, we present a detailed geochemical characterisation and stable isotope systematics of silver (Ag) in a mining waste facility at the Namib Lead & Zinc mine in Namibia (Africa). We examined a series of flotation tailings and ore minerals to address two principal questions: (1) the distribution, chemical form and leachability of Ag, and (2) the local Ag isotopic signature(s) and its variability in relation to Ag speciation in the solid phase, as well as the fate of stable Ag isotopes. Our findings reveal a significant correlation between Ag and Pb concentrations, indicating that galena is the primary Ag carrier. Most importantly, all mild extractions mobilised only a minimal amount of Ag (≤ 1 wt.% of the total amount). This suggests that most Ag is associated with geochemically stable phases, specifically sulphides, which are not subjected to leaching and/or intensive weathering. Unlike other isotope studies, the present research demonstrates a homogeneous Ag isotopic signal in the tailings and individual ore samples with an average δ109Ag value of ~ 0‰ (± 0.1, 2SD). Therefore, this study provides new knowledge and clearly supports the use of Ag isotopic data to track primary Ag sources globally, not only in Africa.

Keywords: critical raw material; extraction; galena; ore; sulphide

Received: December 7, 2025; Revised: December 17, 2025; Accepted: December 18, 2025; Prepublished online: January 14, 2026 

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