Non-classical Mullins-Sekerka instability during mineralization at gas-liquid interfaces

Abstract Diffusion-driven morphological instability, described by Mullins–Sekerka theory, predicts amplification of interfacial perturbations and wavelength selection for idealized sharp interfaces. However, natural systems rarely satisfy these assumptions. Here, we investigate barite mineralization on the growing interface of CO $$_{2}$$ gas bubbles using 3D focused ion beam scanning electron microscopy (FIB-SEM) tomography, quantitative surface analysis and reactive transport modelling. Bubble morphologies exhibit diffusion-driven instability, with dominant modes consistent with Mullins–Sekerka predictions. However, the interface violates key assumptions of the classical framework; it is porous, transport active, and evolves in pore space confinement, while crystallization proceeds via heterogenous nucleation, producing a polycrystalline interface. We show that diffusion-driven instability persists under these conditions but with modified mode selection, defining a non-classical Mullins–Sekerka regime for gas-liquid interface mineralization. Such dynamics influence pore structure evolution and transport pathways in the subsurface environment.