Large-scale CO2 removal relies on an integrated application of carbon capture, utilization, and storage (CCUS) technologies, including geological storage, chemical conversion, and mineralization. Among these, carbon mineralization is particularly promising, offering a permanent pathway for CO2 sequestration. Ultramafic rocks, such as peridotites, are especially well suited for this process due to their high olivine content and rapid carbon fixation potential. However, their intrinsically low porosity and permeability restrict fluid injectivity and limit reaction efficiency, posing major challenges for large-scale implementation. In the first part of this study, we address the permeability constraint by targeting naturally fractured and weathered peridotite zones, as well as experimentally induced fracture networks [1]. By incorporating triaxial direct-shear (TDS) fixtures into core-flooding experiments and coupling them with X-ray microtomography, weathered dunite samples collected from the Twin Sisters Range (WA) and Jackson County (NC) demonstrated sustained fluid flow and, consequently, enhanced carbonation reactions. Notably, the self-propping effect of in situ induced fractures helped maintain high permeability over extended operational periods, with minimal sensitivity to confining pressures up to 32 MPa. The second part of this study focuses on addressing critical knowledge gaps in carbonation performance within these in situ fractures–specifically, the influence of fluid type (aqueous versus wet supercritical CO2), CO2 concentration, and pore and confining pressures on mineral dissolution and secondary (and tertiary) mineral precipitation. To investigate these effects, we analyzed pre- and post-reaction samples using scanning electron microscopy (SEM), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray fluorescence (XRF). Results indicate that Mg–Fe stoichiometry, rather than olivine content, governs the reaction rate, while the composition of the aqueous CO2 injectant dictates whether dissolution or precipitation dominates. Although supercritical CO2 yielded reaction rates comparable to those of aqueous CO2 under the same pore pressure, the formation of iron–silicate layers inhibited subsequent dissolution and precipitation. These findings provide critical insights into the physicochemical controls on peridotite carbonation and offer practical guidance for optimizing depth, fluid chemistry, and pore pressure conditions to enhance CO2 mineral trapping efficiency.