Mineral-fluid interactions underpin element cycles and have governed the removal of CO2 from the atmosphere over geologic timescales. Various CO2 removal strategies rely on these same natural geochemical processes to securely store atmospheric CO2 and contribute to greenhouse gas emission reduction goals. These CO2 removal strategies require constraint on reaction rates capacity, and CO2 storage security, as well as potential co-benefits and risks. We experimentally investigate the geochemical mechanisms by which CO2 can be captured and stored using Ca- and Mg-rich rock and waste materials. Our work demonstrates that Mg-carbonate minerals can securely store CO2 at Earth’s surface conditions, despite complex formation pathways, and can also remove potentially hazardous metals from solution. However, the distribution and availability of water, as well as the initial chemical composition of the solids strongly govern the fate of CO2 during mineral-fluid interaction. At present, we aim to better constrain the capacity of geochemical CO2 removal and how its efficiency may evolve in response to climate change.