Research on the Rio Tinto has historically focused on oxic zones due to their biotechnological relevance in bioleaching. However, the anoxic zones, despite being less explored, hold immense potential. These zones serve as better analogues for Martian life due to Mars’ oxygen scarcity. The anoxic zones exhibit greater microbial diversity, with microorganisms participating in nitrogen, carbon, iron, and sulfur geochemical cycles. Furthermore, anoxic zones also harbor microbes capable of inverse reactions to those in the oxic zones, offering significant potential for acid and metalliferous water bioremediation and selective metal recovery, crucial for transitioning to a renewable energy-based economy. This chapter encapsulates our current understanding of these anoxic zones and their potential biotechnological applications.