The Mg and SO₄ content of naturally occurring calcite are routinely used as paleoenvironmental proxies. Yet little is known about the mechanisms governing the presence of these ions in carbonate minerals when their formation proceeds via an amorphous precursor. To address this, the transformation of Mg-free amorphous calcium carbonate (ACC) into nanocrystalline high-Mg calcite (HMC) was experimentally studied in solutions containing 27 mM of Mg and a range of 10 to 90 mM of SO₄. The obtained results suggest that ACC is stable for several minutes in the experimental solutions and this amorphous phase actively uptakes Mg and SO₄ that are incorporated in its structure. Additionally, the obtained results suggest that the stabilization of ACC is not affected by its Mg content and that the transformation to HMC is effectively controlled by the abundance of the free Mg²⁺(aq) ion. The transformation of ACC to HMC occurs earlier at elevated SO₄ concentrations because SO₄ limits the availability of Mg²⁺(aq) due to the formation of the MgSO₄⁰(aq) complex. The HMC that is formed from ACC appears as aggregates composed of nanocrystallites and exhibits Mg and SO₄ contents up to 8 and 2 mol% depending on the initial SO₄ concentration in the reactive solution. The precipitated HMC was kept in contact with the reactive solution in order to assess its reactivity for up to 1 year of reaction time. Over time, a continuous exchange of Mg and SO₄ between calcite and reactive solution was observed resulting in enrichment of Mg and depletion of SO₄ affecting the total mass of the aggregates with the distribution of these elements to appear homogeneous in the solid. The high reactivity and the continuous exchange of solutes between the nanocrystalline calcite and the reactive solutions limits the use of Mg and SO₄ content of these HMCs as environmental proxies.

天然存在的方解石的 Mg 和 SO ₄含量通常用作古环境指标。然而，当碳酸盐矿物通过无定形前体形成时，控制这些离子在碳酸盐矿物中存在的机制知之甚少。为了解决这个问题，在含有 27 mM Mg 和 10 至 90 mM SO _{4 的}溶液中，实验研究了无镁无定形碳酸钙 (ACC) 向纳米晶高镁方解石 (HMC) 的转化。所得结果表明 ACC 在实验溶液中稳定了几分钟，并且该非晶相积极吸收 Mg 和 SO ₄被纳入其结构中。此外，所获得的结果表明，ACC 的稳定性不受其 Mg 含量的影响，并且向 HMC 的转变受到游离 Mg ²⁺ (aq) 离子的丰度的有效控制。ACC 向 HMC 的转化在 SO ₄浓度升高时发生得更早，因为 SO _{4 会}因形成 MgSO ₄ ⁰ (aq) 复合物而限制 Mg ²⁺ (aq)的可用性。由 ACC 形成的 HMC 表现为由纳米微晶组成的聚集体，根据初始 SO _{4 的}不同，Mg 和 SO _{4 的}含量高达 8 mol% 和 2 mol%反应溶液中的浓度。沉淀的 HMC 与反应溶液保持接触，以评估其反应性长达 1 年的反应时间。随着时间的推移，观察到方解石和反应溶液之间Mg 和 SO ₄的连续交换导致 Mg 的富集和 SO _{4 的}耗尽影响聚集体的总质量，这些元素在固体中的分布看起来是均匀的。纳米晶方解石与反应溶液之间的高反应性和溶质的连续交换限制了这些 HMC的 Mg 和 SO ₄含量作为环境代理的使用。