Geo(bio)chemistry is one of the most effective tools for exploring and managing natural resources such as oil and gas, underground storage, geothermal reservoirs, and mineral ore deposits. By combining natural fluid samples with thermodynamics and experimental studies on water-gas-rock interactions, we can better understand the deep subsurface processes under varying pressure and temperature conditions and the mobilisation and migration of elements. Moreover, microbial reactions can control the accumulation and release of many compounds, leading either to the formation of mineral deposits or to their dissolution.
Pyrite, for example, is the most common sulphide in the Earth’s crust and occurs in many different types of rock. The mineral can be used to reconstruct a range of bio- and geological processes across a broad spectrum of scales. In the oceans, pyrite is the dominant sink for reduced sulphur and is intimately connected to biological pathways of sulphate reduction. On land, pyrite weathering can be a geologically relevant process leading to carbon release to the atmosphere. As a major gangue mineral phase in hydrothermal ore deposits, the formation and geochemistry of pyrite can be used to investigate and potentially detect ore forming processes.