This publication aims to provide the data, theory, and predictions for the potential long-term outcome of a biodiversity conservation programme at a mining site. The Rio Tinto ilmenite mine in southeastern Madagascar, run by QIT Madagascar Minerals (Rio Tinto QMM), has been chosen as a pilot site to test the tools designed to achieve and quantify net positive impact (NPI) on biodiversity. In the present analysis, biodiversity losses and gains were measured and forecast for the period 2004–2065 (i.e. from the date of the NPI commitment to the anticipated date of mine closure), in order to determine whether the current and proposed mitigation activities of Rio Tinto QMM are sufficient to achieve NPI by closure.