You may have seen a reel saying a startup "turned mercury into gold". The real story is more interesting, and more modest. This post explains what Marathon Fusion actually published, how the physics works, and why it has nothing to do with gold prices today.
What happened
Who. Marathon Fusion is a San Francisco-area startup. Its main business is fuel-processing technology for fusion power plants, systems that recycle fusion fuel quickly so plants run more cheaply. In July 2024 it raised a $5.9 million seed round led by 1517 Fund and Anglo American, which together with a US government ARPA-E award brought total funding to about $6.9 million.
The claim. In July 2025, the company released a paper on its website proposing that future fusion power plants could also produce gold as a by-product. The work was later presented as a poster at the American Physical Society plasma physics meeting, titled "Scalable Chrysopoeia via (n, 2n) Reactions Driven by Deuterium-Tritium Fusion Neutrons" (chrysopoeia is the old alchemy word for making gold).
The physics, simply. Gold has 79 protons. Mercury has 80. You cannot just knock a proton out, but you can go the long way:
A fusion reactor that burns deuterium and tritium gives off very fast neutrons (about 14 MeV).
When one hits a mercury-198 atom, it can knock out two neutrons, leaving mercury-197.
Mercury-197 is unstable. Within days it decays into gold-197, the only stable form of gold.
The numbers. The authors' computer simulations of a tokamak reactor's blanket suggest about 2 tonnes of gold per gigawatt of thermal power per year, without cutting electricity output. They say this could double a fusion plant's revenue. Media reports at the time quoted figures up to about 5 tonnes, so the exact number depends on the design assumptions.
What is real and what is not
No gold has been made this way. The results come from simulations, not an experiment. The paper had not been peer-reviewed when it was released.
No commercial fusion power plant exists yet. The whole idea needs a working fusion reactor running at gigawatt scale. That does not exist anywhere in the world today.
The gold would be radioactive at first. Other gold isotopes made in the process mean the metal would need to be stored for roughly 14 to 18 years before it is safe to handle, according to reports on the paper.
Experts are interested but cautious. A US Department of Energy plasma physicist who reviewed the study told the Financial Times it "looks great" on paper. Other commentators point out that simulations can miss real-world effects, and that reactor materials able to survive the radiation still need to be developed.
So a fair one-line summary is: a credible fusion startup published a simulation showing future fusion plants could make gold as a side product. It is a proposal, not a result.
Why it matters for you
Gold prices: no effect now. Even on the startup's own numbers, gold would only flow once gigawatt-scale fusion plants exist, plus a decade or more of storage. Nothing about this changes what gold costs in India this year. Gold prices are moved by the dollar, interest rates, central-bank buying and import duty, not this paper.
Ignore "fusion gold" investment pitches. If anyone sells you a coin, token or scheme linked to "fusion gold", treat it as a red flag. No such product exists.
The bigger story is fusion economics. The real point of the paper is that fusion plants might earn money from more than electricity. That could help fusion reach the market sooner, which matters for India's long-term energy needs.
What to watch next
Peer review. Whether the full paper passes independent peer review, and whether other groups reproduce the simulation.
A physical test. Any small experiment that confirms the mercury-198 to gold reaction rate with real fusion neutrons.
Fusion timelines. Progress from fusion companies and projects such as ITER. Without working fusion plants, there is no fusion gold.
Good to know
This is not financial advice. Do not change any gold investment decision based on this story.
Some reels say the company "turned mercury into gold". That is not accurate. It modelled how a future reactor could do it.
Making tiny amounts of gold from other elements is not new. Particle accelerators have done it in trace amounts for decades. What is new here is the claim that it could be done at tonne scale cheaply inside a power plant.
Sources
APS Division of Plasma Physics 2025: Scalable Chrysopoeia via (n, 2n) Reactions poster abstract
Mugglehead: US startup claims it can turn mercury into gold at scale
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