Editorial for the Special Issue of Minerals: “Mineral Dissolution and Precipitation in Geologic Porous Media”

Mineral dissolution and precipitation alter the pore structure, permeability, and chemical and mechanical properties of subsurface rocks, shaping the behaviors of water resources, hydrogeology, contaminant transport, geologic carbon/hydrogen storage, and geo-energy operations. This process results in liquid–solid interfaces evolving in rock porous media, where reaction rates depend on fluid transport through tortuous pore networks, while fluid transport, in turn, depends on how reactions roughen and coat pore surfaces or clog pore spaces. Even in relatively simple systems (e.g., calcite–water system [1,2,3]), prediction remains difficult due to the complexity arising from reactive transport coupled with interfacial processes and spatial heterogeneity. Historically, there have been three important types of investigations performed to address this challenge: (i) X-ray computed microtomography (micro-CT) imaging [4,5,6], which quantifies evolving porosity, connectivity, tortuosity, etc.; (ii) reactive transport modeling [7,8,9,10,11,12], which links kinetics and geometry across scales; and (iii) microfluidic experiments, which visualize and capture real-time pore-scale dynamics of reaction and transport [3,13,14,15]. These efforts uncovered a variety of patterns and mechanisms that govern mineral dissolution and precipitation, allowing us to gain a better understanding of geologic porous media and contributing to better engineering of such media.

Despite substantial progress in characterizing pore-scale reactions and modeling reactive transport, the field still lacks an integrated understanding that connects fundamental interfacial processes to macroscale system behavior across diverse geologic settings. Emerging applications—such as large-scale CO₂ and H₂ storage, engineered mineralization, and sustainable subsurface energy systems—demand predictive frameworks that can account for coupled chemical, physical, and biological processes under dynamic conditions. This gap highlights the need for a dedicated platform to bring together innovative experimental, observational, and computational advances. This Special Issue aims to provide that platform, fostering cross-disciplinary dialogue and accelerating the development of next-generation approaches for probing and controlling mineral dissolution and precipitation in porous media.

Bearing the above visions in mind, this Special Issue seeks to contain a balanced mix of experimental and computational works. Contributing papers range from Darcy-scale modeling of microbially induced calcite precipitation (MICP) [16], kinetic Monte Carlo (KMC) simulations of crystal growth in fractures [17], in situ micro-CT imaging of iron precipitation and flow reorganization [18], and organics-templated calcite nucleation and its characterization [19] to a state-of-the-art review of biogeochemistry for underground hydrogen storage (UHS) [20]. These contributions advance this Special Issue’s focal areas: (a) reactive transport mechanisms and aqueous–mineral interfaces; (b) abiotic/biotic crystal growth; (c) novel characterization of phases and structures; (d) multiscale/multi-physics couplings; and (e) integrative reviews of recent progress.

Among the contributions, Wang et al. [16] developed an improved Darcy-scale model for MICP that coupled flow, the advection–diffusion–reaction of mobile species, bacterial attachment/growth, and precipitation-driven porosity–permeability evolution via the Kozeny–Carman relationship. Validated against a long-column experiment, the model examined two critical parameters: initial porosity heterogeneity (average and correlation length) and injection strategy (continuous vs. phased). Two findings were important for field operations: (i) at low average porosity, longer correlation lengths amplified cementation heterogeneity, while above a threshold of ϕ₀ ≈ 0.45, that dependence weakened; (ii) phased injections extended the treated zone and increased CaCO₃ mass compared with continuous injection, which can be useful for reducing inlet clogging. Their study exemplified themes (a) and (d) and demonstrated feasible steps to embed a widely used geochemical engine (PHREEQC) in a multi-physics solver. This model helps connect pore-scale reaction dynamics with Darcy-scale flow behavior in realistic MICP treatments by providing the mechanistic coupling needed to translate laboratory insights into predictive tools for reservoir conditioning and subsurface remediation.

Rodrigues et al. [17] used kinetic Monte Carlo (KMC) simulations calibrated with AFM (atomic force microscopy)-informed step velocities to map calcite growth on rough calcite fracture walls. Two idealized geometries, wedge-shaped walls and vicinal walls with monolayer steps (<1 nm roughness), were employed to ascertain the essential physics of the fracture-filling process. Step propagation was shown to fill valleys. In wedges, growth halted upon reaching low-energy planes, leaving a residual gap, whereas on vicinal surfaces, step flow clogged the fracture. Scaling arguments related timescales to geometry and step velocity (i.e., saturation). The key insight is that crystallography dominates over geometric roughness in controlling end states, which is vital for predicting sealing vs. stabilization under supersaturated flow and for setting Damköhler-based design criteria. This sharpens theme (b) and informs upscaling toward continuum-scale models.

Cao et al. [18] co-injected Fe (II)-rich freshwater and oxygenated saltwater through a bead pack with time-elapse micro-CT imaging. Three distinct stages were identified: (i) early mobile hydrous iron precipitates intermittently clog and reopen pores; (ii) accumulation and interparticle bonding redirect flow, including wall proximal flushing; and (iii) a transition from viscous- to capillary-dominated flow as the macroscopic capillary number drops from ≈3 to ≈ 0.05yields ramified flow channels. The segmentation-to-pore-network workflow of CT images linked evolving solids to hydraulic consequences (tortuosity orientation and connectivity). Methodologically, the paper advances theme (c) and demonstrates pore-to-Darcy upscaling, central to theme (d). Their study also highlights the critical role of high-resolution imaging in bridging pore-scale and continuum-scale dynamics in hydrogeochemical processes.

Testa et al. [19] tested whether common fatty acids (palmitic and stearic acids), abundant in biofilms, could template carbonate nucleation. SEM (scanning electron microscopy)/TEM (transmission electron microscopy) imaging showed spheroidal organic structures of palmitic and stearic acids spatially associated with calcite. The work provides direct laboratory evidence consistent with Extracellular Polymeric Substance (EPS)-mediated carbonate nucleation seen in natural settings and experiments, reinforcing themes (b) and (c).

Viveros et al. [20] reviewed the gas–liquid–rock–microbe interactions most consequential for UHS, including hydrogenotrophic sulfate-reducing bacteria, methanogens, acetogens, and iron-reducers, and mapped 76 ongoing European projects. Their review detailed gas loss, souring/corrosion, mineral precipitation/dissolution, biofilm growth, and wettability impacts, and highlighted knowledge gaps in in situ kinetics, field-scale monitoring, and constitutive links between biofilms and petrophysical properties. Framing hydrogen as both an energy carrier and a microbial electron donor positions microbial risks and their induced biogeochemistry as a central design variable for safe, efficient UHS, advancing theme (e) and connecting to themes (a–d).

Looking ahead, the studies collected in this Special Issue highlight a broader shift in how mineral dissolution and precipitation in porous media must be investigated and applied. The contributions demonstrate that predictive capability increasingly depends on explicitly resolving feedback among transport processes, interfacial kinetics, evolving microstructure, and biological activity. As subsurface technologies progress toward large-scale implementation—including carbon and hydrogen storage, geothermal systems, and engineered mineralization—simplified or weakly coupled descriptions of these processes will limit reliability and scalability.

Future advances will require tighter integration of pore-scale observations, microstructurally informed modeling, and field-scale validation under realistic chemical and hydrodynamic conditions. Particularly promising directions include the development of standardized workflows for transferring imaging-derived geometries, wettability states, and reactive surface properties into continuum-scale constitutive models, as well as improved quantification of biogeochemical reaction rates under in situ conditions. A future Special Issue could productively focus on uncertainty-aware upscaling strategies, the long-term evolution of reactive porous media under cyclic operation, and the treatment of microbial processes as active design variables rather than secondary effects.