The dissolution of powdered Carrara marble was investigated in the absence and in the presence of (1-hydroxyethylidene)-1,1-diphosphonic acid (HEDP) at conditions of constant undersaturation at pH 8.25. The dependence of the rates of dissolution on the relative undersaturation suggested a surface diffusion controlled mechanism. According to this mechanistic information, the interaction of HEDP with calcitic Carrara marble was investigated. Two types of interaction of the HEDP with the marble suface were studied: preadsorption and addition of HEDP in the undersaturated solutions (1 muM to 1 mM). In both cases the rates of dissolution were drastically reduced depending on the concentration of the organophosphorus compound on the marble surface or in the undersaturated solutions. The rate reduction was attributed to the poisoning of the active dissolution sites through the uptake of HEDP on the calcite crystallites of the Carrara marble. The HEDP uptake by marble was measured quantitatively. The zeta potential was calculated from electrokinetic measurements of marble particle suspensions as a function of pH, pCa, and PCO32-. The potential-determining ions of the calcitic marble showed that the uptake of HEDP by the calcitic marble particles resulted in a shift of the surface potential to negative values and over a wide pCa range (2.0-4.5), causing charge reversal. The variation of the suspension pH did not result in significant changes of the surface potential. The examination of the morphology of the dissolving marble grains showed that the initially present small crystallites dissolved first, while in the presence of HEDP, which retarded dissolution, they were preserved.