A San Francisco-based fusion startup called Marathon Fusion has made a bold claim that has gold markets and investors talking. The company says it has successfully turned mercury into real, stable gold using neutrons generated from nuclear fusion — a modern version of the ancient alchemist’s dream.
In a post on X on 21 October 2026, Marathon Fusion announced that last month it achieved “high-rate alchemy,” producing gold at a rate ten times higher than a record set by CERN in 2025. The company is also working on medical isotopes for cancer treatment and is building a small fusion reactor in San Francisco.
How Does It Work?
The process is based on nuclear transmutation. High-energy neutrons from a deuterium-tritium fusion reaction hit mercury-198 atoms. This converts them into mercury-197, a radioactive isotope that decays over a few days into gold-197 — the only stable form of gold found in nature.
In a 2025 research paper, the company estimated that a full-scale fusion power plant generating one gigawatt of thermal power could produce around two tonnes of gold per year as a byproduct (some statements mention up to five tonnes per gigawatt of electricity). For comparison, the entire world mines about 3,600–3,700 tonnes of gold annually.
The Big Caveats
Experts urge caution. Marathon Fusion has not publicly shared how much gold it actually produced in its experiment, nor details on purity, cost, or efficiency. CERN’s earlier efforts produced only tiny amounts — about 29 picograms over several years. The company’s current reactor is still at a very small scale (around 1 kilowatt).
Any gold produced this way may initially contain radioactive isotopes and could need years of storage before it is safe for commercial use. Commercial fusion power plants themselves are still years or decades away from widespread operation.
What Could This Mean for Gold Prices?
If the technology ever scales up successfully, it could significantly increase the global supply of gold. That has raised comparisons with lab-grown diamonds, which expanded supply and put long-term pressure on natural diamond prices.
In the short term, the announcement alone is unlikely to crash the market — the quantities involved are still microscopic. But if investors start believing large-scale production is possible in the future, it could weigh on sentiment and prices.
Global impact: Gold is already under pressure. Prices have fallen sharply from their January 2026 peaks and recently slipped below $4,000 an ounce. Extra potential supply from fusion plants could add to the downside over the longer term, especially if multiple reactors come online.
Impact on India: India is one of the world’s largest gold consumers, especially for jewellery during festivals and weddings. Lower global prices would make gold more affordable for Indian buyers and could boost jewellery demand. However, it could hurt domestic gold miners, jewellers holding large inventories, and investors who treat gold as a store of value. Import bills might ease, but the cultural and investment role of gold in India means any sustained price drop would be closely watched.
For now, Marathon Fusion’s claim is exciting science rather than an immediate market game-changer. Independent verification, bigger-scale results, and actual commercial production will decide whether lab-made gold remains a laboratory curiosity or becomes a real threat to traditional gold prices.