Tailings generated from metal mining and mineral processing have become a global environmental liability, of which economic costs and ecological impacts are threatening the "social licence to operate" in the mining and mineral processing industry. Rehabilitation of tailings domain with sustainable vegetation cover is severely hindered by the lack of topsoil and/or inert materials to reconstruct root zones. Direct revegetation to initiate primary succession of pioneer plant communities has largely failed due to biotoxic conditions in the tailings, which are far beyond the promised potential of plant-based phytostabilization approach.
Recent research findings with Cu and Pb-Zn tailings and bauxite residues have demonstrated that pedogenic processes may be primed and accelerated in situ towards the formation of functional technosol, by treating tailings as novel parent materials and applying effective ecological engineering inputs (i.e., engineered pedogenesis). The direct/indirect weathering of reactive minerals is critical to the initiation and acceleration of the engineered pedogensis in tailings. Current results show that geo-microbial power can be effectively harnessed to prime-start the weathering of tailings minerals and the formation of large amounts of secondary minerals, which are much required for reaching the initial hydrogeochemical stabilization and later particle aggregation and soil structure development. Successful transition or shifts in microbial communities from geo-microbe dominance to soil-microbe dominance are another critical leap toward the formation of functional tailing-soil which is equipped with soil-like biogeochemical processes and functions much required for sustaining the productivity and diversity of established plant communities. From our own research findings and literature review, the paper will discuss functions of different groups of geo-microbes in the weathering of metal mine tailings with different mineralogy and geochemistry and inherent bioweathering processes for target minerals. Knowledge gaps in regulatory mechanisms of bioweathering are identified for future research attention.