Fig. 1

Schematic of our model system. Two unstable minerals, A and B, are located on opposite sides and interact through a fluid conduit of length L. A replacement reaction occurs at each mineral surface. Minerals A and B react with rates \(R_{\mathrm{A}}\) and \(R_{{\mathrm{B}}}\) respectively, and the chemical formulas of their precipitates are expressed as \(\mathrm {A}_{X_{\alpha }^{{\mathrm{A}}}} \mathrm {B}_{1-X_{\alpha }^{{\mathrm{A}}}}\), and \(\mathrm {A}_{X_{\alpha }^{\mathrm{B}}} \mathrm {B}_{1-X_{\alpha }^{{\mathrm{B}}}}\), respectively. Note that the precipitating solid-solution mineral \(\mathrm {A}_{X_{\alpha }} \mathrm {B}_{1-X_{\alpha }}\) is a different mineral from the dissolving minerals, A and B. The concentration profiles of species \(\alpha\) and \(\beta\) in the fluid channel are also shown. The linear concentration gradients of \(C_{\alpha }\) and \(C_{\beta }\) are obtained under an assumed steady-state condition. The concentrations of \(\alpha\) and \(\beta\) are completely coupled, indicating a single-component system (see text). Notably, the newly precipitated minerals are assumed to exist only at one side of the respective dissolved minerals and not to fill the fluid conduit