Natural rock-derived microfluidic chip for probing multicomponent mineral dissolution dynamics

Abstract

Mineral dissolution plays a fundamental role in key subsurface processes, involving complex coupling among fluid flow, mass transport, and geochemical reactions. In this study, we present microfluidic chips fabricated from natural carbonate rocks using laser micromachining with a layer-by-layer strategy. The chips are optically transparent with a non-reactive basal surface, preserving mineralogical heterogeneity while enabling real-time, high-resolution visualization of dissolution. Four representative carbonate rocks—calcite, mixed-mineral, dolomite, and multi-mineral—were investigated to assess the influence of mineral composition and heterogeneity on dissolution dynamics. Results show that mineral composition strongly governs dissolution patterns: calcite rocks develop wormhole structures, while low-reactive dolomite rocks exhibit compact patterns. Notably, in mixed carbonate rocks containing both calcite and dolomite, even when calcite accounts for up to 33% of the composition, the overall dissolution dynamics—including the effective reaction rate—are mainly dominated by dolomite. Micro-mechanistic analysis indicates that this occurs because the highly reactive calcite dissolves preferentially, creating new pores between the less reactive dolomite crystals. This limits the effective transport of reactive fluid, thereby suppressing further reaction. The remaining dolomite framework eventually dissolves completely, resulting in a compact dissolution pattern. In contrast, in multi-mineral rocks rich in quartz and clay, the inert minerals accumulate at the reaction front, forming a stable dissolution-altered layer, which macroscopically manifests as a negligible change in particle morphology. This study establishes a versatile experimental platform for investigating fluid–rock interactions in subsurface engineering and provides new insights into how mineral composition and heterogeneity influence dissolution behavior in natural rocks.