Biogeochemical processes in canga ecosystems: Armoring of iron ore against erosion and importance in iron duricrust restoration in Brazil

•Canga is a unique iron duricrust that caps and protects supergene enriched iron ores.•Geochemical evidence suggests surface processes contribute to ongoing canga evolution.•Iron cycling by plants and microbes is likely a significant process in canga.•Iron mine restoration will benefit from understanding these biogeochemical processes.