A Catalyst\nTube-Equipped Dual-Stage Tube Furnace System\nfor Accurate Hg Isotopic Determination of Ore Samples Using Neptune\nPlus Multicollector Inductively Coupled Plasma Mass Spectrometry

Mercury (Hg) isotopes, which display mass-dependent fractionation\nand mass-independent fractionation, provide a multidimensional tracer\nto decipher the source of metals in mineral deposits. However, mineral\nore samples usually contain abundant interfering elements (e.g., Te)\nthat can cause inaccurate Hg isotopic analysis. Available acid digestion\nand combustion methods failed to remove these interfering elements,\nhindering the application of Hg isotopes for metallogenetic tracing.\nHere, we developed a new dual-stage tube furnace system employing\na Mn-containing catalyst tube to pretreat mineral ore samples. This\nmethod yielded good Hg recoveries (100.5 ± 3.8%, 1SD, n = 15)\nand low levels of interfering elements in sample solutions, allowing\nfor accurate analysis of a series of ore standard reference materials\n(GBW-11108v: coal; GSO-3: Cu–Ag sulfide ore; GBW 07859: Au–Te\nsulfide ore). The new method was also successfully applied to measure\nthe Hg isotopic composition of magmatic and hydrothermal ore deposits,\nwhich yielded a large range in Δ<sup>199</sup>Hg value (−0.19\nto 0.22‰) for ore deposits formed in different geological settings,\nhighlighting the future applications of this method for metallogenic\ntracing, especially tracing the source of metals in mineral ore deposits.