A complete series of calcite-rhodochrosite solid solutions [(Ca1-xMnx)CO3] are prepared, and their dissolution processes in various water samples are experimentally investigated. The crystal morphologies of the solid solutions vary from blocky spherical crystal aggregates to smaller spheres with an increasing incorporation of Mn in the solids. Regarding dissolution in N2-degassed water, air-saturated water and CO2-saturated water at 25 °C, the aqueous Ca and Mn concentrations reach their highest values after 1240–2400 h, 6–12 h and < 1 h, respectively, and then decrease gradually to a steady state; additionally, the ion activity products (log_IAP) at the final steady state (≈ solubility products in log_Ksp) are estimated to be − 8.46 ± 0.06, − 8.44 ± 0.10 and − 8.59 ± 0.10 for calcite [CaCO3], respectively, and − 10.25 ± 0.08, − 10.26 ± 0.10 and − 10.28 ± 0.03, for rhodochrosite [MnCO3], respectively. As XMn increases, the log_IAP values decrease from − 8.44 ~ − 8.59 for calcite to − 10.25 ~ − 10.28 for rhodochrosite. The aqueous Mn concentrations increase with an increasing Mn/(Ca + Mn) molar ratio (XMn) of the (Ca1-xMnx)CO3 solid solutions, while the aqueous Ca concentrations show the highest values at XMn = 0.53–0.63. In the constructed Lippmann diagram of subregular (Ca1-xMnx)CO3 solid solutions, the solids dissolve incongruently, and the data points of the aqueous solutions move progressively up to the Lippmann solutus curve and then along the solutus curve or saturation curve of pure MnCO3 to the Mn-poor side. The microcrystalline cores of the spherical crystal aggregates are preferentially dissolved to form core hollows while simultaneously precipitating Mn-rich hexagonal prisms.

中文翻译：

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方解石-菱锰矿固溶体[（Ca _1-x Mn _x）CO ₃ ]在25°C的溶解度和溶解度

制备了一系列完整的方解石-菱锰矿固溶体[（Ca1-xMnx）CO3]，并通过实验研究了它们在各种水样中的溶解过程。固溶体的晶体形态从块状球形晶体聚集体到较小的球体，随着固体中Mn含量的增加而变化。关于在25°C下在N2脱气水，空气饱和水和CO2饱和水中的溶解，Ca和Mn水溶液的浓度分别在1240-2400 h，6-12 h和<1 h之后达到最高值，并且然后逐渐下降到稳定状态；此外，方解石[CaCO3]的最终稳态下的离子活性产物（log_IAP）（≈log_Ksp中的溶解度产物）估计分别为-8.46±0.06，-8.44±0.10和-8.59±0.10，以及-10.25 ±0.08，− 10.26±0。菱锰矿[MnCO3]分别为10和− 10.28±0.03。随着XMn的增加，方解石的log_IAP值从− 8.44〜− 8.59降低至菱锰矿的−10.25〜− 10.28。随着（Ca1-xMnx）CO3固溶体的Mn /（Ca + Mn）摩尔比（XMn）的增加，Mn水溶液的浓度增加，而XMn = 0.53-0.63时，Ca水溶液的浓度最高。在构造的不规则（Ca1-xMnx）CO3固溶Lippmann图中，固体不相容地溶解，水溶液的数据点逐渐向上移动到Lippmann溶质曲线，然后沿着纯MnCO3的溶质曲线或饱和度曲线移动到锰贫乏的一面。