Silver is probably the closest isotopic proxy to track monoisotopic gold and has been shown to have great potential to yield new information on the origin and enrichment processes of gold. This study describes the development of a tailored analytical protocol for accurate analysis of Ag isotopes and provides the first Ag isotope data for the Paleoproterozoic Rajapalot Au-Co deposit, Finnish Lapland. Six native Au samples yield ε¹⁰⁹Ag values (relative to NIST SRM 978a) from −6.8 to +2.1 and are within the range of Ag isotopic compositions reported for native Au samples. The mean of the analyzed Au samples is ε¹⁰⁹Ag = −3.8 ± 1.7 (2SD) with most of the samples with negative ε¹⁰⁹Ag values (−6.7 to −2.0); one sample has a positive ε¹⁰⁹Ag value of +2.1 ± 0.5. Silver isotope fractionation in the Rajapalot Au deposit was likely associated with physicochemical processes related to deposition and/or re-mobilization of the ore rather than with source region inheritance. It is suggested that redox reactions involving Ag⁺ ↔ Ag⁰ phase change primarily account for the isotopic differences within the deposit. Our results also suggest that the Rajapalot Au-Co deposit was formed via multistage ore-forming processes and/or that the primary ore was re-mobilized, which caused isotope fractionation along fluid pathways. Silver isotope variation within a deposit may mark a fractional crystallization trend with the lightest isotopic composition representing the earliest precipitate. Hence, Ag isotopes show potential as an isotopic vectoring tool in search of Au-enriched domains.

白银可能是追踪单一同位素金的最接近的同位素代理，并已被证明具有提供有关金的起源和富集过程的新信息的巨大潜力。这项研究描述了用于准确分析银同位素的定制分析方案的开发，并为芬兰拉普兰古元古代拉贾帕洛特金钴矿床提供了第一个银同位素数据。六个天然金样品产生从 -6.8 到 +2.1 的 ε ¹⁰⁹ Ag 值（相对于 NIST SRM 978a），并且在天然金样品报告的银同位素组成范围内。分析的 Au 样品的平均值为 ε ¹⁰⁹ Ag = -3.8 ± 1.7 (2SD)，大多数样品具有负 ε ¹⁰⁹ Ag 值（-6.7 至 -2.0）；一份样品的 ε ¹⁰⁹ Ag 值为 +2.1 ± 0.5。Rajapalot 金矿床中的银同位素分馏可能与矿石沉积和/或再活化相关的物理化学过程有关，而不是与源区继承有关。这表明涉及 Ag ⁺ ↔ Ag ⁰相变的氧化还原反应主要解释了矿床内的同位素差异。我们的研究结果还表明，拉贾帕洛特金钴矿床是通过多阶段成矿过程形成的和/或原生矿石被重新活化，从而导致沿流体路径的同位素分馏。矿床内的银同位素变化可能标志着分级结晶趋势，最轻的同位素组成代表最早的沉淀物。因此，Ag 同位素显示出作为寻找富 Au 域的同位素矢量工具的潜力。