Marathon Fusion Claims Mercury-to-Gold Breakthrough, Raising Questions for Bullion Markets

Marathon Fusion, a San Francisco fusion energy startup, said Wednesday it transmuted mercury into stable gold last month, a claim not independently verified that beats CERN's record tenfold and revives fears lab-made gold could disrupt bullion markets as lab-grown diamonds did to diamonds. The company said its method fires neutrons from fusion reactions at mercury, creating an unstable isotope that decays into gold. Marathon, founded in 2023, lists the US Department of Energy as a partner and counts Breakthrough Energy and Anglo American among its backers. It did not disclose how much gold was produced or at what cost. Gold traded at $4,062 an ounce Thursday, more than 27% below its January record of $5,598. Mines produced 3,672 tonnes in 2025, according to the World Gold Council. Marathon's 2025 study estimated a fusion plant could make about 5 tonnes of gold annually per gigawatt; 100 plants would add roughly 500 tonnes a year, about 14% of last year's mine output. No fusion plant yet sells electricity, and the company said the gold could contain radioactive isotopes requiring storage for up to 18 years.