On October 21, 2026, fusion-energy startup Marathon Fusion announced on the social platform X that it had converted mercury into stable gold using neutrons produced by nuclear fusion. The San Francisco-based company said the achievement came at a production rate ten times higher than CERN's 2025 record, according to Glitchwire's review of the company's post.
In its post, Marathon Fusion described the result as turning mercury into real, stable gold at a rate ten times faster than CERN's 2025 figure, Glitchwire reported after reviewing the announcement. The company did not publish supporting data alongside the claim.
How the mercury-to-gold process is supposed to work
According to Glitchwire's review of the claim, the method starts with mercury-198, an abundant stable isotope. Fast neutrons generated by deuterium-tritium fusion strike the mercury and knock out a neutron, turning it into mercury-197. That isotope then decays into stable gold-197, with a half-life of roughly 64 hours, Glitchwire reported. The Conversation added that neutrons above 6 million electron volts are needed to trigger the transformation.
Euronews reported that, according to the company's own study, gold made this way would initially be radioactive and would need to be stored for up to 18 years before it could be sold safely.
Comparing the claim with CERN's gold
Marathon Fusion's claim versus CERN's 2025 gold record| Metric | CERN (ALICE experiment) | Marathon Fusion claim (Oct. 2026) | Modeled fusion plant |
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| Method | Lead-ion collisions at the Large Hadron Collider | 14 MeV fusion neutrons striking mercury-198 in a lab reactor | Fusion reactor blanket processing mercury at industrial scale (not built) |
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| Gold quantity | About 29 picograms over roughly four years of running, per The Conversation | Not publicly disclosed; company says the rate is 10x CERN's, per Glitchwire | Euronews reported a company estimate of about 5 tonnes of gold per gigawatt of electric power per year; The Conversation described the projection only as 'several tonnes' per gigawatt of thermal power annually, without a precise figure |
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| Verification | Published, peer-reviewed physics result | Announced via social media; no data, purity or efficiency figures released, per Glitchwire | Based on computer simulations ('a digital twin'), not a real plant, per The Conversation |
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| Scale in operation | Operating particle collider | 1-kilowatt test reactor planned in San Francisco, per Glitchwire | Hypothetical gigawatt-scale commercial fusion plant; none exist yet, per The Conversation and Euronews |
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What the company has not shown
- No independent, peer-reviewed confirmation of the October claim has been published, according to The Conversation and Glitchwire.
- Marathon has not disclosed the total amount of gold produced, its isotopic purity or the efficiency of the conversion process, Glitchwire reported after reviewing the company's announcement.
- No commercial fusion power plant exists anywhere to test whether the economics in Marathon's modeling would hold up in practice, The Conversation noted.
- The company's planned test reactor in San Francisco is rated at about 1 kilowatt of fusion power, a small fraction of the gigawatt scale used in its commercial projections, according to Glitchwire.
Why transmuting gold has long been difficult
The Conversation noted that at CERN's rate of about 29 picograms of gold over four years from lead-ion collisions, producing a single troy ounce would take roughly hundreds of times the current age of the universe. Fusion neutrons are considered a more promising route than particle collisions because they can trigger the needed decay sequence in mercury more efficiently, but doing so still requires neutron fluxes and reactor conditions that have not yet been demonstrated commercially, the outlet reported.
Who is behind Marathon Fusion
Marathon Fusion was founded in 2023, according to Glitchwire. The company raised at least $6 million in seed funding, with investors including the 1517 Fund, mining company Anglo American and Breakthrough Energy, Glitchwire reported. Glitchwire added that the U.S. Department of Energy's ARPA-E program provided $449,065 for related fuel-cycle research between 2023 and 2025.
Could lab-made gold affect prices?
Euronews drew a comparison to the market for lab-grown diamonds, whose wholesale prices fell 90–95% from 2015 levels once synthetic stones reached volume production. Unlike diamonds, the outlet noted, fusion-made gold would be chemically indistinguishable from mined gold once its radioactivity decays. However, Euronews also reported that no commercial fusion plants currently exist, meaning any effect on gold markets remains theoretical for now.
Questions
- Did Marathon Fusion really turn mercury into gold?
- The company says it did, using fusion-generated neutrons to convert mercury-198 into gold-197. However, outlets including The Conversation and Glitchwire note the claim has not been independently verified and no supporting data on quantity or purity has been published.
- How much gold did Marathon Fusion actually produce?
- The company has not disclosed the amount. It says only that its production rate was ten times higher than CERN's 2025 record of about 29 picograms of gold over roughly four years, according to Glitchwire and The Conversation.
- Is the fusion-made gold radioactive?
- Yes, initially. Euronews reported that, per the company's own study, the gold would need up to 18 years of storage before it could be sold because of residual radioactivity.
- Could this process crash gold prices?
- Euronews raised the comparison to lab-grown diamonds, whose wholesale prices fell 90–95% after synthetic production scaled up, but noted that no commercial fusion plants exist yet, so any market impact remains speculative.
- Who funds Marathon Fusion?
- The company raised at least $6 million in seed funding, with investors including the 1517 Fund, mining firm Anglo American and Breakthrough Energy, plus a U.S. Department of Energy ARPA-E grant of $449,065, according to Glitchwire.
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