The discovery, using short wavelength infrared radiation (SWIR), that some low-sulfidation epithermal gold deposits are associated with hydrothermal alteration involving ammonium minerals, particularly buddingtonite ((NH₄)AlSi₃O₈), has led to the suggestion that the gold may have been transported as a complex involving ammonia (NH₃). The speciation of gold in ammonia-rich solutions, however, has received little attention from experimentalists and, consequently, it is not known whether gold forms stable complexes with NH₃ and whether such species could contribute significantly to the transport of gold in epithermal ore-forming systems. To resolve this issue, we have conducted experiments to investigate the speciation and solubility of gold in ammonia-bearing solutions at temperatures of 225 and 250 °C under vapour-saturated water pressure with oxygen fugacity buffered by the assemblage magnetite-hematite. Based on the results of these experiments, gold does form stable species with ammonia at elevated temperature. The gold is interpreted to have been dissolved predominantly as Au(NH₃)OH⁰ in solutions with a NH₃⁰ concentration of 0.005 ∼ 0.49 m and a pH(T) of 3.29 ∼ 7.47. This species formed via the reaction, Au _(s) + NH_{3 (aq)} + H₂O = Au(NH₃)OH_(aq) + 1/2 H_{2 (g)} The logarithms of the equilibrium constant for this reaction are −8.95 ± 0.84 and −7.71 ± 0.85 for 225 and 250 °C, respectively. In order to determine whether this species is important for the transport of gold in epithermal systems, we modeled the speciation of gold in a fluid at conditions typical of those epithermal gold depositing fluids. This modeling shows that the solubility of gold as AuHS⁰ and Au(HS)₂^- is much higher than that as Au(NH₃)OH⁰ except in alkaline ammonia-bearing fluids. The association of gold mineralization with hydrothermal alteration involving the formation of ammonium-bearing minerals in the deposits is therefore probably unrelated to the transport of gold as a Au-NH₃ complex but simply reflects the high concentration of NH₄⁺ in the ore-forming fluid.

使用短波红外辐射 (SWIR) 发现一些低硫化超热液金矿床与涉及铵矿物的热液蚀变有关，特别是绿锂石 ((NH ₄ )AlSi ₃ O ₈ )，这表明金可能已作为涉及氨（NH ₃）的复合物运输。然而，金在富氨溶液中的形态很少受到实验者的关注，因此，尚不清楚金是否与 NH _{3形成稳定的络合物}以及这些物种是否会对浅热成矿系统中的黄金运输做出重大贡献。为了解决这个问题，我们进行了实验，以研究在 225 和 250 °C 的温度下，在蒸汽饱和水压下，金在含氨溶液中的形态和溶解度，氧逸度由磁铁矿 - 赤铁矿组合缓冲。根据这些实验的结果，金在高温下确实会与氨形成稳定的物质。金被解释为主要以 Au(NH ₃ )OH ⁰形式溶解在 NH ₃ ⁰浓度为 0.005 ∼ 0.49 m 和 pH(T) 为 3.29 ∼ 7.47 的溶液中。这种物质通过反应形成，Au _(s)  + NH_{3 (aq)}  + H ₂ O = Au(NH ₃ )OH _(aq)  + 1/2 H _{2 (g)}对于 225 和 250，该反应平衡常数的对数为 -8.95 ± 0.84 和 -7.71 ± 0.85 ℃，分别。为了确定该物种是否对超热液系统中金的运输很重要，我们模拟了在这些超热液金沉积流体典型条件下流体中金的物种形成。该模型表明，金作为 AuHS ⁰和 Au(HS) ₂ ^-的溶解度远高于作为 Au(NH ₃ )OH ^{0的溶解度}碱性含氨液体除外。因此，金矿化与热液蚀变的关联，包括矿床中含铵矿物的形成，可能与金作为 Au-NH ₃络合物的输运无关，而只是反映了成矿过程中 NH ₄ ⁺的高浓度。体液。