The concept of hazard in the current interpretation of the European and national regulations is directed to local and short-term effects and its assessment is based on the distribution in space of the concentration of contaminants in abiotic and biotic compartments. We expand this concept and address its limitations by describing potential hazard with full space–time dimension, i.e., from short term to long term, and from local to regional. This most straightforward technique to quantify hazard is biogeochemical and based on the scale-specific processes of metals mobility. The short-term hazard of a contaminated area (and its future hazards in different environmental scenarios) depends on the stocks of metals, on the fluxes of outgoing elements, and on the retention time of the elements (ratio between stock and sum of fluxes). Different hazard situations can result from the relative importance of the intensity of the carrier flux and the mobilization of metals by the carrier flux. The analyses of long-term hazard can relocate a contaminated site from one hazard situation to another because of changes in the intensity of the carrier flux or/and of the mobility of metals. The mineralogical aspects controlling the stocks of metals in contaminated areas and the outgoing fluxes of metals are discussed analytically by type of source and type of flux and research directions are identified. Finally, the specific example of hazard evaluation for Romanian tailing dams is presented based on the approach introduced here.