A generic method for producing potentials to model organic-mineral systems is proposed. The method uses existing potentials for the components of the system and produces cross-term potentials between these components. The existing potentials are fitted to known mineral structures modeled with charges that mimic the Coulombic potential at the organic-mineral interface. The method has been applied to supply a set of potentials to model calcite biomineralization, including water-calcite, bicarbonate ions, and a set of organic functional groups with calcite. Tests comparing the results from ab initio and other potential-based calculations demonstrate that the new potential set is reliable and accurate.