The New Alchemy: U.S. Startup Claims It Can Make Five Tons of Gold a Year

If you thought medieval alchemists faded into history alongside elixirs and philosopher’s stones, meet Marathon Fusion. This San Francisco-based startup isn’t just promising fusion power—it’s aiming to transmute elements. Specifically: up to five metric tons of pure gold annually, straight from the heart of a nuclear reactor.

It sounds like science fiction, but the idea is rooted in real nuclear physics. At the core is a gigawatt-scale tokamak reactor equipped not only with a standard tritium-breeding blanket but also with stable mercury-198. Under neutron bombardment, Hg-198 becomes unstable Hg-197, which then decays into gold-197. Clean, precise nuclear alchemy—on paper.

But here comes the caveat. The resulting gold must be safely stored for 14 to 18 years until its residual radioactivity decays to safe levels. So no gold wedding rings just yet. And before anyone starts fantasizing about billion-dollar windfalls, there’s an even colder splash of reality: commercial fusion reactors don’t exist. Marathon’s entire vision hinges on a field still defined by that slippery word—hope.

Reactors like SPARC or HH70 haven’t crossed the commercial threshold. Even if they do, thorny questions remain about production costs, neutron flux availability, and how to manage the radioactive tail of the gold itself. As one expert dryly put it: “technically correct, practically impossible.”

Still, Marathon Fusion is undeterred. They believe this golden byproduct—potentially worth $545 million per year—could make fusion investments more appealing and accelerate the entire sector. The idea is outrageous, bold, and potentially transformative. If it ever works, it could trigger a new gold rush that reshapes the very idea of secure wealth.

But until reactors are cranking out gigawatts and gold by the crate, Marathon’s “new alchemy” remains a rich blend of fantasy, scientific intrigue, and a speculative investor’s fever dream.