Fusion-Made Gold Faces Scale and Cost Hurdles as Bitcoin’s Supply Cap Holds

A new route to gold, with a long path to market

Marathon Fusion’s claim that it has produced gold from mercury raises an interesting question about scarcity: if technology can add to the supply of a traditionally scarce asset, does Bitcoin’s fixed issuance schedule become more compelling? For now, the practical impact looks remote. The company’s result is microscopic, and a commercial process would depend on fusion infrastructure that does not yet exist.

The method described in Marathon’s research paper uses high-energy neutrons from a deuterium-tritium fusion reaction to irradiate mercury-198. That produces a radioactive isotope which decays into stable gold-197. The process is nuclear transmutation, rather than a chemical method of separating or reshaping existing gold.

Marathon says it produced stable gold at a rate ten times CERN’s record. That comparison needs context: CERN’s ALICE experiment generated an estimated 29 picograms of gold nuclei from 2015 to 2018, and the nuclei lasted only fractions of a second before being destroyed in collisions. Marathon hasn’t disclosed the exact amount from its own experiment. Research engineer Jake Harter says the output remains “right now still microscopic,” with the company aiming for “macroscopic milligram quantities in 2027.”

Nuclear fusion turned mercury into gold. Source: Marathon Fusion

The much larger figures in the paper describe a hypothetical future power plant, not current production. Marathon models annual output of about two tonnes of gold per gigawatt of thermal fusion power. The World Gold Council reported that mines produced 3,672 tonnes globally in 2025. Even at the paper’s projected rate, one fusion plant would supply a modest share of that total.

The economics remain the bigger question

Getting from a laboratory result to a dependable source of marketable gold requires more than increasing the reaction’s output. Harter says Marathon would need to scale production of the enriched mercury used in the process and build a fusion reactor. The company also plans studies on materials compatibility, mercury pumping and gold extraction.

Those engineering steps sit alongside a more basic uncertainty: whether producing gold this way could ever make financial sense. “There is no demonstration that the process is commercially viable,” says Nikos Kavalis, managing director at precious metals research firm Metals Focus. He points to theoretical revenue projections, but says there is no corresponding account of reactor operating costs. In his assessment, “We are nowhere near a stage where we can talk about production significance.”

Lab-grown diamonds offer an appealing comparison because their prices fell sharply as production scaled. Wholesale prices have declined by more than 90% since 2018, and lab-grown diamonds have the same chemical composition as mined stones. Coinbase CEO Brian Armstrong has drawn a parallel, arguing that new gold made through “alchemy” could follow a similar path. His point about Bitcoin is simpler: “There will only ever be 21M,” he said.

But the analogy has limits. Nagham Hassan, a market analyst at eToro, says the economics of the two production methods are “completely different.” Diamond factories can become more efficient as they expand; making gold through fusion would require highly complex infrastructure that has no commercial deployment today, she said.

Marathon Fusion research paper. Source: Marathon Fusion

There is also a handling constraint. The newly produced gold would be radioactive. Harter says it would need to be stored for a little over a decade before its radioactivity fell to “banana-levels.” He argues that a wait may not prevent early commercial use, since much gold is held as an investment. Still, the radioactive period adds another practical requirement to an already demanding production chain.

What it means for gold and Bitcoin

A sustained increase in supply could affect an asset’s market price, all else being equal. Fabian Schär, professor of distributed ledger technology and fintech at the University of Basel, says a substantial rise in available supply would put downward pressure on price. That principle makes the idea of an “infinite mint bug” easy to grasp, but Marathon’s work has not shown that fusion can add meaningful quantities of gold to the market.

The company’s co-founder and CEO, Kyle Schiller, says Marathon has received strong interest from jewelers. He expects any fusion-made gold to be used mainly as a store of value, much like conventional gold. Interest from potential users is a signal of curiosity, though it doesn’t answer the questions of cost, production volume or timing.

For Bitcoin, the distinction is between a fixed protocol supply and a commodity whose supply could, in principle, expand through new production methods. Armstrong’s argument is that no one can invent a way to increase Bitcoin’s 21 million coin limit. If fusion-made gold eventually became economical and plentiful, it could put pressure on gold’s scarcity narrative. That possibility remains speculative, while Bitcoin’s supply rule is already part of its design.

The timing matters. The first fusion reactors are estimated to be at least a decade away, and Marathon’s projected gold output assumes a future plant operating at scale. The company’s current work is an intriguing demonstration of nuclear transmutation, not evidence of a near-term change in gold supply. The useful takeaway for industry observers is to watch the engineering and cost milestones: until those are demonstrated, the debate over digital gold remains largely theoretical.

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