Knowledge of chemical reactions and physical processes at the atomic level is crucial to solving many problems in the geosciences. For example, biomineralisation of carbonates and phosphates is still far from understood and yet is vital to nature and biomimetic science. In the case of carbonates, these geochemical processes are also relevant to long-term geosequestration of CO2. Other atomistic processes, such as those controlled by defects in minerals, are responsible for water incorporation into the Earth’s mantle and are ultimately responsible for the convection that drives plate tectonics. Computer simulation provides a powerful tool to determine the relationship between atomistic detail and the macroscopic properties of minerals.