Marathon fusion claims to invent alchemy, making 5000 kgs gold per gigawatt
71 comments
·July 18, 2025semicolon_storm
philipkglass
It's the second lightest natural isotope of mercury, comprising about 10% of natural mercury:
https://en.wikipedia.org/wiki/Isotopes_of_mercury
Since mercury forms vapor so easily, it should be easily enriched in gas centrifuges like uranium (more easily, actually, since the starting isotopic abundance is higher and the chemistry is simpler). The high price of purified mercury-198 at present is probably due to it being a scientific curiosity with no industrial demand.
oh_my_goodness
That's even better! We can turn gold into mercury-198 and sell that. Gold is dirt cheap at $0.11 per mg. We're rich!
floxy
There are 7 stable isotopes of mercury, and mercury-198 makes up ~10% of naturally occurring mercury. The paper covers a lot of ground here, see section 5.2.2 "Mercury Isotope Separation", where they are shooting for $2.4/kg.
RA2lover
It's 10% of natural mercury. you're looking into separating it cheaply instead, or at least hope the other naturally occuring isotopes don't cause too many problems.
BoiledCabbage
If it's that easy to separate from natural mercury then it seems like they could make a fortune just separating it and selling the separated mercury.
Something isn't adding up
0cf8612b2e1e
Maybe there is not a huge need for isotopically pure mercury so the current price is not reflective of acquisition/manufacturing costs?
modeless
Unfortunately gold generated in this way would be radioactive. They calculate they would have to store the gold for over 13 years to not require labeling as radioactive waste, or over 17 years to reach the level of radioactivity of a banana.
I bet it would still be less valuable than regular gold even after that. It could still be identified, and people would discriminate against it. People are funny about nuclear waste, and likely wouldn't accept arguments like "it's perfectly safe" and "it's less radioactive than a banana".
floxy
>In practice, given that much of all gold is used to store value and is not actively in use, we do not expect the need to store it for 7–17 years to be a major impediment; at worst, it means that the product will initially have somewhat less value than pure 197Au, and so some discount should be applied to the value of freshly produced gold.
lantry
but when we are generating literal tons of gold for free, won't gold no longer be a good store of value because it will no longer be scarce?
ChuckMcM
This is not a problem for finance bros, they would sell a discounted note that gave you "ownership" of the gold in 17 years at some discount on the current spot price of gold. So you'd get these things that 'mature' in 17 years and you know their going to be worth whatever the spot price of gold is then, so it becomes a simple problem of pricing the risk that gold will be worth something in 17 years (people by gold futures all the time which this basically is).
bb88
The treasury sells bonds that mature after X years. So I suspect something similar could happen. But further there could be refinement if the radioactive isotopes could interact chemically in ways that gold couldn't.
Then they could sell pure gold, and then hold the crap gold for 20 years and sell that later.
BTW, I was at Teardown.
stogot
I’d hold crap gold for retirement at a discount today
Waterluvian
That seems like so little time it’s just a slight detail to iron out.
I also doubt it would be worth much less. I suspect most gold physically sits idle for longer periods of time while changing ownership often.
Aeolun
17 years to banana is basically free money.
K0balt
Theres always money in the banana stand!
0cf8612b2e1e
Most gold does not even leave the vaults. Just paper trades on who owns it.
bravesoul2
Bitcoin solves this by being goldless
more_corn
There’s always money in the infinite gold to banana scam.
mtzaldo
It reminded me of avocado trees. They take a couple of years to produce avocados and still people plant those.
OutOfHere
That thought fails altogether since it will do perfectly well sitting in a vault as a reserve for a 1:1 gold backed crypto coin. Of course this holds true only until its value collapses due to its lack of scarcity.
Ekaros
Well for gold that will be placed in some vault dig deep into the ground that doesn't seem too bad trade off..
shutupnerd0000
Imagine a whiskey manufacturer saying "this is impossible because we'll have to age it for 13 years" lel
modeless
Imagine a whiskey manufacturer saying "our whiskey is radioactive but it's ok because it will be less radioactive by the time you drink it!"
readthenotes1
Skoal!
chaboud
Actual industrial/product use of gold is less than 10%. A massive amount of gold is used for store of wealth. If gold became less scarce, it would be less expensive.
The Washington monument capstone is aluminum because aluminum was expensive in 1884. Now we make beverage containers out of aluminum. (note: I have no intention of using gold for beverage containers... I like my skin not blue)
MereInterest
> (note: I have no intention of using gold for beverage containers... I like my skin not blue)
I thought gold was biologically inert. Any chance you’re thinking of argyria, which is caused by exposure to elemental silver?
josephcsible
> I like my skin not blue
Isn't that problem just with silver, not gold?
oh_my_goodness
Even if this were true, at 0.15 USD/kWh it would cost more than just buying the gold. Even excluding cost of cleaning up the radioactivity, the equipment, labor, everything except the power.
A GW-year is 8760 GWh. That's 8760/5000 = 1.75 GWh per kg of gold. At 0.15 USD/kWh, a GWh costs $150k US. So 1.75GWh costs about $263k. A kg of gold costs about 100k US.
modeless
The gold is a byproduct of generating the electricity. You still get to sell the electricity too.
dwattttt
Gold is atomically heavier than iron, fusing gold costs energy. The language in the article is ambiguous, but I believe the energy quoted is a cost.
floxy
They are engineering their tritium breeding to produce excess neutrons to transmute the mercury to gold.
modeless
It's produced from mercury
amelius
Yeah, but the gold price is going to drop ...
oh_my_goodness
Wait, really?
one-note
> Using our approach, power plants can generate five thousand kilograms of gold per year, per gigawatt of electricity generation (~2.5 GWth), without any compromise to fuel self-sufficiency or power output.
snickerdoodle12
Third paragraph from the post, in bold:
> Using our approach, power plants can generate five thousand kilograms of gold per year, per gigawatt of electricity generation (~2.5 GWth), without any compromise to fuel self-sufficiency or power output.
floxy
Yes, that is their selling point
kristianp
This is such a fun topic to think about, it's nearly science-fiction. The problem with fusion plants is that they don't exist except as small experimental reactors. I think this could be retrofitted to existing fission plants, pumping mercury 198 gas around the outside of the core (in heat-resistant pipes of course). Still an expensive proposition as you'd want to certify that it's not going to affect the safety and reaction rates of the reactor.
Another thought is that gold is a useful product, so anything that reduces the price of gold is good for the industries that use it. Are there other rare elements that are more useful, though?
a1371
15 cents per kWh is much more expensive than what you buy electricity for around the world. Also, they can time their usage for when the electricity is free or very cheap
ChuckMcM
EDIT Note: Sharp eyed commentators pointed out I misread the table, which makes the economics better. I had originally 3% but updated it to 10%
Hmmm, mercury-198 is 10%[1] of mercury, of which in 2022, China was the top supplier at 2000 tonnes[2], so 200 tonnes of that is the "good stuff". Not a lot of easy access to open data on Mercury spot prices, this source[3] has it at $2000 per flask which is 76 lbs or 34.5 kg. Using our 10% number that's 7.6lbs per flask. Which if you convert that into 7.6lbs of gold you can sell it for a bit over $300K. So not too bad. Presumably a lot of currently shut down mercury mines might start up again, but you're adding 9 tonnes of mercury 'waste' to get your 1 ton of Hg-198. The cost of disposing that might be challenging. If you could sell it back at the current spot price for mercury by flask it would be great, but with all the extra supply I think the price might go down? Which kind of helps your economics until someone only puts mercury on the market that they have already removed the HG-198 from. Being vertically integrated with your own mercury mines and reserves would be good here.
The thing I don't get is why fusion? I mean you can get fast neutrons out of fission too, what sort of gamma flux do you need to generate Hg-197? Can the LHC do this trick? I mean seriously can you put a beaker of mercury in the beam path and transmute 3% of it to gold? Seems like a way to get budget for more experiments right?
[1] https://chemlin.org/isotope/mercury-198
[2] https://worldpopulationreview.com/country-rankings/mercury-p...
philipkglass
I think you read that table a little quickly. Mercury-198 is 10% of natural mercury.
According to the paper, you need neutrons of at least 9 MeV to drive the transmutation. Fission reactions don't generate neutrons with energies that high. A proton accelerator can generate high energy neutrons by spallation, but in smaller numbers. It wouldn't be economically viable to do this with accelerator generated neutrons.
The paper shows that neutrons from deuterium-tritium fusion are energetic enough (14.1 MeV) to drive the transmutation reaction, and they're a natural byproduct of a D-T fusion reactor, and adding this extra gold generating step shouldn't compromise the ordinary fuel breeding and power generating operations of a commercial fusion reactor.
So now all they need is a commercial fusion reactor. I say that with tongue firmly in cheek, but also impressed that working fusion reactors (if they ever arrive) can also upend the current gold market.
JSR_FDED
If about 4 million KG of gold is normally produced a year, then this newly available gold will quickly drive down prices, leaving only Bitcoin as a store of value. Talk about unintended consequences…
OutOfHere
Rhodium and iridium can become very valuable, more than they are now, if they're relatively impractical to produce cheaply using fusion.
dr_dshiv
Fuck, yes, this is the future I want. Great job guys, keep at it!
Also—I appreciate the alchemical aspects. A nice aesthetic for a future vision.
bravesoul2
I dont trust a site that simultaneously says "we are performing a once in a century technical feat" and "we can only say great things about this like we are selling something and not mention potential pitfalls".
cheaprentalyeti
OK, I looked at their web site and couldn't find how they were supposed to be reaching fusion. Can anyone here point me in the right direction?
floxy
From the paper:
>Using neutronics simulations, we demonstrate a tokamak with a blanket configuration that can produce 197Au at a rate of about 2 t/GWth/yr.
LargoLasskhyfv
The first link on their site is alchemy.pdf behind announced a solution. Maybe read that? (40 pages) Or not, because here is the abstract ;)
Abstract A scalable approach for chrysopoeia—the transmutation of base metals into gold—has been pursued for millennia. While there have been small-scale demon- strations in particle accelerators and proposals involving thermal neutron capture, no economically attractive approach has yet been identified. We show a new scalable method to synthesize stable gold (197Au) from the abundant mer- cury isotope 198Hg using (n, 2n) reactions in a specialized neutron multiplier layer of a fusion blanket. Reactions are driven by fast 14 MeV neutrons provided by a deuterium-tritium fusion plasma, which are uniquely capable of enabling the desired reaction pathway at scale. Crucially, the scheme identified here does not negatively impact electricity production, and is also compatible with the challenging tritium breeding requirements of fusion power plant design because (n, 2n) reactions of 198Hg drive both transmutation and neutron multiplication. Using neutronics simulations, we demonstrate a tokamak with a blanket configu- ration that can produce 197Au at a rate of about 2 t/GWth/yr. Implementation of this concept allows fusion power plants to double the revenue generated by the system, dramatically enhancing the economic viability of fusion energy.
impish9208
Isaac Newton must be spinning in his grave.
readthenotes1
"I knew mercury was involved. Just knew it!"
https://www.chemistryworld.com/news/newtons-recipe-for-alche...
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leereeves
To be clear, this is something that would be wrapped around a fusion power plant (capturing neutrons produced by fusion), not a viable fusion plant itself nor a way to generate gold from just any power plant, right?
It requires mercury-198 as an input. The only quote I could find for mercury-198 is about $15K per milligram.
So now we just need to figure out how to make mercury-198 cheaply.