Reply to Revil, A. (2025), Comment on ‘A physical interpretation of Cole–Cole equations and their ambiguous time constants for induced polarization models’ by James Macnae

SUMMARY Revil asserted in the comment that none of Macnae’s paper is novel. The paper however introduced a novel method of chargeability prediction as the fraction of pores blocked by metallic particles rather than the prediction using limiting Maxwell effective medium estimates based on volume fractions. This reply presents an analysis of two cases where the novel chargeability prediction proves to be significantly better than earlier methods when applied to laboratory pyrite–clay mixtures and to published petrophysical data from a Co–Cu disseminated mineral deposit. Another item of novelty in the paper was emphasis that the resistivity and conductivity time-constants can differ by orders of magnitude for the high chargeabilities of economic sulphide deposits, a fact not commonly recognized in the literature. Revil asserts in the comment that the term Induced Polarization (IP) should explicitly exclude dielectric effects and analogies as discussed in the paper, an assertion inconsistent with the early literature on IP and the fact that both diffusive and dielectric effects can affect low-frequency data. The reply provides detail on the physical nature of equivalent circuits, and how they can mechanistically model the IP phenomenon and the topology of conductive paths in materials, an issue that I did not emphasize in the paper as I thought it would have been obvious to most readers.