Tag: critical minerals

Scandium: The Element Too Scarce to Use

Global scandium production is approximately 25-40 tonnes per year. Projected demand is 117 tonnes per year by 2026. That gap — roughly three to four times more demand than supply — is not the result of a sudden crisis, an export control, or a geopolitical shock. It is the normal state of the scandium market. It has been the normal state for decades. Scandium is the critical mineral that has never had enough supply to discover how much demand actually exists, because the industries that would use it — aerospace, automotive, fuel cells, 3D printing — have never been able to buy it in quantities large enough to justify designing it into their products. Adding 0.1-0.2% scandium to aluminum creates an alloy that is 15-20% lighter than conventional alternatives, weldable without losing strength, corrosion-resistant, and suitable for aircraft fuselages, EV frames, and naval vessels. Approximately $2 million of scandium in a single airliner yields an estimated $27 million in net present fuel savings over the aircraft’s life. The economics are spectacular. The supply doesn’t exist to act on them. The Soviet Union discovered this first — the MiG-21 and MiG-29 used aluminum-scandium alloys in their airframes starting in the 1960s — and the West has been trying to replicate the supply chain ever since. As of 2026, it still hasn’t.

Why there isn’t enough

Scandium is more abundant in the Earth’s crust than silver, lead, or mercury. It is not geologically rare. It is economically rare because it has almost no affinity for the common anions that form concentrated ore deposits — meaning it is spread thinly across the lithosphere rather than concentrated into mineable veins. There is, at the time of this writing, essentially one dedicated scandium mine on Earth: Scandium International Mining’s operation in New South Wales, Australia. Everything else is by-product recovery.

Scandium is recovered in small quantities from the processing of other metals — iron ore, rare earths, titanium, zirconium, uranium, and nickel laterite tailings. China produces the most, primarily from titanium dioxide production and rare earth processing. The Philippines, Kazakhstan, Russia, and Ukraine produce smaller amounts from nickel laterites and uranium operations. None of these producers are mining for scandium. They are recovering it as a residue from processes designed for other purposes — the same by-product supply ceiling that constrains indium, tellurium, rhenium, hafnium, and the noble gases.

But scandium adds a dimension the other by-product metals don’t have. Rhenium is scarce, but the aerospace industry has designed around it — jet engine superalloys are formulated to use rhenium because the supply, though small, has been stable enough for turbine manufacturers to commit. Hafnium is scarce, but Intel adopted hafnium oxide in 2007 because 75 tonnes per year was enough for the semiconductor industry’s needs at the time. Scandium has never reached the supply threshold where a major industry could commit to using it at scale. The result is a chicken-and-egg problem that has persisted for half a century: manufacturers won’t design products around scandium because supply is unreliable, and miners won’t invest in scandium production because manufacturers haven’t committed to buying it. The market is stuck at 25-40 tonnes per year, with latent demand estimated at 5-10 times that level, and no mechanism to bridge the gap.

What it would do if you could get it

Aluminum-scandium alloys account for roughly 45% of scandium oxide consumption. The metallurgy is straightforward: adding 0.1-0.2% scandium by weight to aluminum refines the grain structure, eliminates the heat-affected zone weaknesses that make conventional aluminum alloys difficult to weld, and produces a material that can be reliably joined without post-weld heat treatment. That weldability property alone could transform aircraft manufacturing — currently, aluminum aircraft structures are largely riveted because the welding of conventional aerospace aluminum degrades the metal’s strength at the weld. Aluminum-scandium alloys can be welded without strength loss, which means fewer fasteners, lower weight, faster assembly, and simpler structural designs. The weight reduction translates directly into fuel savings for every flight the aircraft makes for 30 years.

The automotive sector sees the same economics. Net aluminum content per light-duty vehicle is projected to increase from 459 pounds in 2020 to 570 pounds by 2030. If just 10% of that aluminum used 0.1% scandium, annual scandium demand from automotive alone would reach 700 tonnes — roughly 20 times current global production. The EV industry has an even stronger incentive: every kilogram removed from an EV extends its range, and range is the constraint that determines consumer adoption. The aluminum-scandium value proposition in EVs is not theoretical. It is purely a supply problem.

Solid oxide fuel cells are the other growth engine — currently representing roughly 15-55% of global scandium consumption, depending on which estimate you use. Bloom Energy, the leading commercial SOFC manufacturer, uses scandia-stabilized zirconia electrolytes because scandium is a better ionic conductor than yttrium in this application — it allows the fuel cell to operate at lower temperatures, extending operational lifetime and reducing maintenance costs. A typical 100-kilowatt Bloom Energy server box contains 13-15 kilograms of scandium oxide. SOFC deployment is growing at roughly 23% compound annual growth rate. If scandium supply doesn’t grow with it, SOFC manufacturers will either pay dramatically more for feedstock or switch back to yttrium-stabilized zirconia — a substitution that trades performance for availability, at a moment when yttrium’s own supply chain is experiencing a 4,400% price spike.

The supply response that might be coming

Rio Tinto opened a scandium oxide plant in Sorel-Tracy, Quebec, in 2021, producing up to 3 tonnes per year from its existing titanium dioxide feedstock. In 2024, Rio Tinto acquired Platypus Alloys — an Australian company producing aluminum-scandium master alloy — signaling that the world’s second-largest mining company sees a market worth vertically integrating into. NioCorp Developments holds a scandium resource of 11,000 tonnes at its Elk Creek site in Nebraska and projects production capacity of 100-135 tonnes per year of scandium oxide, though the project has not yet reached construction. In Europe, the ScaVanger project in France targets 21 tonnes per year of scandium oxide from titanium dioxide coproduction, with production projected to begin in 2026. Clean TeQ (now Sunrise Energy Metals) in Australia has significant scandium resources in its nickel-cobalt laterite deposits.

The project pipeline exists. The production doesn’t — not yet. If NioCorp, ScaVanger, and Rio Tinto all deliver on their stated timelines, global non-Chinese scandium supply could triple by 2028. That would still leave the market short of projected demand, but it would break the chicken-and-egg cycle by giving aerospace and automotive OEMs enough material to design aluminum-scandium into production platforms rather than test programs. The question is whether the projects get built before the demand window closes — before alternative lightweighting technologies (carbon fiber, magnesium alloys, advanced high-strength steel) lock in the market share that aluminum-scandium could have captured if the supply had existed five years earlier.

Why it’s in the course

Scandium is the Rare Earth Elements course’s case study in suppressed demand — the mineral whose scarcity has prevented the market from discovering its own size. Every other mineral in the course has a functioning market: lithium has a price, a supply chain, a demand curve. Copper has a shortage. Antimony had a price spike. Terbium has export controls. Scandium has a hypothetical market that is 5-20 times larger than the actual market, with the gap explained entirely by supply that has never existed in sufficient quantities for demand to materialize. The gallium/germanium export controls disrupted an existing supply chain. Scandium’s disruption is that the supply chain was never built.

China classified scandium as a national strategic material in the April 2025 export controls — the same announcement that restricted terbium, samarium, and yttrium. For most of those elements, the controls created a crisis. For scandium, the controls restricted a supply that was already too small to matter. The crisis isn’t the export control. The crisis is that the element the Battlefields of the Future course identifies as capable of making fighter jets 15-20% lighter and the energy transition identifies as capable of making fuel cells more efficient has been stuck at 25 tonnes a year for a generation because nobody built the mine.

This is the kind of supply chain our Rare Earth Elements course was built to map — where the most economically valuable aluminum additive ever discovered, deployed by the Soviet military sixty years ago, remains a curiosity rather than a commodity because global production has never exceeded two shipping containers, the industries that would use it can’t commit because supply doesn’t exist, and the mines that would produce it can’t justify the investment because demand hasn’t materialized — the purest chicken-and-egg trap in the critical minerals landscape.
Hafnium: The Element Inside Every Advanced Chip That Nobody Mines

Every semiconductor chip manufactured at process nodes below 45 nanometers — which, as of 2026, includes every processor in every smartphone, every data center server, every AI accelerator, and every advanced military system on Earth — uses hafnium. Not in the packaging. Not in the wiring. In the transistor itself. Hafnium oxide replaced silicon dioxide as the gate dielectric in 2007 when Intel introduced its 45-nanometer process, because silicon dioxide at that thickness — just a few atoms wide — leaked too much current for the transistor to function. Hafnium oxide has a higher dielectric constant, meaning it can be physically thicker while remaining electrically thinner, which solved the leakage problem and made every subsequent generation of chip miniaturization possible. No hafnium, no chips below 45 nanometers. No chips below 45 nanometers, no modern computing. Global hafnium metal production is approximately 75 tonnes per year. Total production including oxides is roughly 85 tonnes. Demand is projected to reach 150-200 tonnes per year. Prices have risen 400% in recent years. And hafnium has no dedicated mine anywhere on Earth — it is produced exclusively as a by-product of zirconium refining, at a ratio of roughly 50 tonnes of zirconium for every 1 tonne of hafnium. The by-product supply ceiling that constrains indium, tellurium, the noble gases, and rhenium applies here — but hafnium’s version has a twist. Rhenium is a by-product of a by-product. Hafnium is a by-product of a by-product’s purification: it only exists as a separated element because the nuclear industry requires hafnium-free zirconium for reactor fuel cladding, and the process of removing hafnium from zirconium produces hafnium as a residue. If the nuclear industry didn’t need ultra-pure zirconium, nobody would be separating hafnium at all.

Three sectors, one element, 75 tonnes

Hafnium’s demand splits across three sectors that are all growing simultaneously and all drawing from the same 75-tonne annual pool.

The first is semiconductors. Hafnium oxide — HfO₂ — is the gate dielectric in every advanced transistor. Intel, TSMC, Samsung, and every other foundry running sub-45nm processes deposit hafnium oxide films measured in angstroms — fractions of a nanometer — onto billions of transistors per wafer, millions of wafers per year. As transistor geometries shrink to 3 nanometers, 2 nanometers, and eventually below, hafnium oxide remains the standard gate dielectric. DRAM memory cells use hafnium oxide for the same reason: its high dielectric constant allows capacitors to store charge in smaller physical spaces. The semiconductor supply chain has its famous chokepoints — TSMC in Taiwan, ASML in the Netherlands, neon from Ukrainian air separation units, yttrium coating the etching chambers. Hafnium is the chokepoint nobody talks about because nobody has had to — the 75 tonnes has been enough, barely, with no margin. The question is what happens when demand reaches 150 tonnes and production can’t follow.

The second is nuclear energy. Hafnium absorbs neutrons more effectively than almost any other material — a property that makes it essential for reactor control rods, the components that regulate the chain reaction by absorbing excess neutrons when inserted into the reactor core. Every pressurized water reactor, every boiling water reactor, every naval nuclear propulsion system uses hafnium control rods. The nuclear renaissance the fusion companies post documented — Microsoft restarting Three Mile Island, Google’s Kairos Power deal, Amazon’s Talen Energy acquisition, China’s plan to build six to eight reactors annually — is accelerating hafnium demand from the nuclear sector at the same time the semiconductor sector is accelerating demand from the electronics side. Both sectors drawing from the same 75-tonne pool. The pool doesn’t get larger because neither sector demands more zirconium.

The third is aerospace superalloys. Hafnium is added to nickel-based single-crystal superalloys — the same CMSX-4 and René N5 alloys that contain rhenium — to improve grain-boundary strength and oxidation resistance at extreme temperatures. Hafnium-enriched superalloys tested in gas turbines and jet engines deliver 10-15% improved creep resistance at 1,200°C compared to baseline compositions. The Boeing and Airbus backlog of 15,000+ aircraft that drives rhenium demand drives hafnium demand through the same turbine blades. Every jet engine blade that needs rhenium inside it also needs hafnium inside it.

And then there’s the emerging sector: plasma cutting. Hafnium-tipped plasma torch electrodes survive 6,000°C arcs and last 30% longer than conventional designs. Industrial metal cutting, shipbuilding, heavy fabrication — every plasma cutter in every shipyard and fabrication shop uses hafnium electrode tips that are consumed during operation and must be replaced. It’s a small market in tonnage terms. In a 75-tonne global pool, small markets matter.

The zirconium dependency

The hafnium supply chain is the most structurally constrained by-product chain in the Rare Earth Elements course — more constrained than rhenium (by-product of a by-product via copper-molybdenum), more constrained than indium (by-product of zinc), because hafnium’s separation is tied not just to a host metal’s production economics but to a specific purification process that exists for a specific customer: the nuclear fuel industry.

Zirconium is mined as zircon — a mineral found in beach sand and alluvial deposits in Australia, South Africa, Brazil, and other countries. Most zircon is consumed directly as a ceramic material in tiles, foundry molds, and refractory linings — applications that do not require removing the hafnium. Only the nuclear industry requires hafnium-free zirconium, because hafnium’s neutron-absorbing properties are exactly the opposite of what you want in a fuel rod cladding material — zirconium is chosen precisely because it is transparent to neutrons, but natural zirconium contains 1-2.5% hafnium, which must be removed to achieve nuclear-grade purity.

The separation process — typically a solvent extraction or extractive distillation operation — is concentrated in a handful of facilities worldwide. Orano (formerly Areva) operates five plants in France through its Cezus subsidiary. ATI and Western Zirconium operate in the United States. Chepetsky Mechanical Plant operates in Russia. Chinese facilities serve China’s domestic nuclear and semiconductor demand. The total global capacity for zirconium-hafnium separation produces roughly 75 tonnes of hafnium per year. That capacity was built to serve the nuclear fuel industry’s demand for pure zirconium. The hafnium was the waste product that someone figured out how to sell. Expanding hafnium production requires expanding nuclear-grade zirconium separation — a capital-intensive process justified by nuclear fuel demand, not by hafnium demand.

China’s internal consumption of hafnium — for both its nuclear reactor construction program and its semiconductor industry — absorbs most of its domestic output, leaving little for export. After 2024 restrictions tightened the flow, Japan’s semiconductor supply chain, South Korea’s foundries, and India’s aerospace programs became increasingly dependent on French and American separation facilities. The CHIPS Act invests billions in semiconductor fabrication. The hafnium oxide that goes inside the transistors those fabs produce comes from a separation process built to serve the nuclear fuel industry, at volumes that were never designed to support the semiconductor industry’s growth trajectory.

Why it’s in the course

Hafnium is the Rare Earth Elements course’s purest demonstration that a material can be simultaneously indispensable and invisible. Every chip below 45 nanometers uses it. Every nuclear reactor control rod uses it. Every advanced turbine blade uses it. Global production is 75 tonnes. Nobody mines it on purpose. It exists as a separated element only because the nuclear industry needs it removed from something else. And the three sectors that need it — semiconductors, nuclear energy, aerospace — are all growing at the same time, all pulling from the same pool, with no mechanism to expand the pool independently of nuclear fuel demand.

The lithium supply chain has a demand problem that can be solved by building lithium mines. The copper supply chain has a capacity problem that can be solved by building copper mines. The rhenium supply chain has a by-product problem that can only be solved by expanding copper-molybdenum mining. Hafnium has a by-product problem that can only be solved by expanding nuclear-grade zirconium separation — a process that exists to serve one industry, produces a residue consumed by three others, and cannot be scaled by any of the three industries that need the residue, because none of them control the process that produces it.

This is the kind of supply chain our Rare Earth Elements course was built to map — where every transistor manufactured below 45 nanometers depends on 75 tonnes a year of a metal that nobody mines, separated from a mineral the nuclear industry needs purified, at a ratio of 50 to 1, by a handful of facilities built for a different purpose, with three industries competing for the output and none of them able to increase it.
Yttrium: The 4,400% Price Spike Nobody Saw Coming

In January 2025, yttrium oxide traded at roughly $6 per kilogram in Europe. By November, it was $270. That’s a 4,400% increase in under eleven months — the most extreme price spike of any critical mineral in the 2025 export control cycle, larger in percentage terms than antimony’s 4x move, larger than terbium’s surge, and orders of magnitude more violent than anything the lithium market has produced in its most volatile cycles. Chinese domestic yttrium oxide, meanwhile, sat at roughly $7 per kilogram — 16% above January levels. The gap between the Chinese and European price was not 50%, not 100%, not 500% — it was approximately 3,700%, an arbitrage that existed entirely because of China’s April 2025 export licensing requirements and the market’s inability to move material across the border. A rare earth trader told Reuters that their yttrium stocks had fallen from 200 tonnes to 5 tonnes. Another said they were out of stock entirely. The Aerospace Industries Association told Washington that yttrium was essential to the world’s most advanced jet engines and that the supply chain depended almost entirely on China. A semiconductor industry source rated the severity of the yttrium shortage as “9 out of 10.” The United States imports 100% of its yttrium. Ninety-three percent comes directly from China. The remaining 7% is made from material that was first processed in China. The critical minerals supply chain had seen gallium restricted, graphite restricted, antimony restricted, terbium restricted, samarium restricted. Yttrium was the restriction that hit the semiconductor fabs and the jet engine factories simultaneously.

What yttrium does

Yttrium — element 39, a silvery metal more abundant in the Earth’s crust than silver but economically rare because it is difficult to separate and refine — occupies a peculiar position in the rare earth family. It is grouped with the heavy rare earths despite sitting slightly apart on the periodic table, because its chemistry behaves like the heavies. Its industrial applications span at least five distinct sectors, each of which would, on its own, justify classifying yttrium as strategic.

The first is aerospace thermal barrier coatings. Yttria-stabilized zirconia — a ceramic compound of yttrium oxide and zirconium dioxide — is the standard thermal barrier coating applied to jet engine turbine blades and gas turbine components. The coating protects the underlying nickel superalloy (rhenium-containing, in many cases) from the 1,400-1,700°C combustion gases that would otherwise destroy it. Without the yttria-stabilized zirconia layer, no modern jet engine achieves its operating temperature. GE, Rolls-Royce, Pratt & Whitney, Mitsubishi Heavy, Siemens Energy — every turbine manufacturer in the world uses yttrium in thermal barrier coatings. The rhenium post documented the superalloy inside the turbine blade. The yttrium post documents the ceramic coating on the outside. If the rhenium makes the blade survive the heat, the yttrium makes the survival possible.

The second is semiconductor manufacturing equipment. Yttrium oxide coatings line the interior of plasma etching chambers — the machines that carve circuit patterns into silicon wafers. The coating resists the corrosive fluorine and chlorine plasmas used in the etching process. Without yttrium oxide linings, the chamber walls degrade, contaminating wafers and reducing yield. Semiconductor fabs consume yttrium not in the chips themselves but in the equipment that makes the chips — a distinction that matters because equipment coating replacement is a continuous operational expense, not a one-time manufacturing input. Every etching cycle degrades the yttrium coating incrementally. Every fab needs a steady resupply. When that resupply stopped flowing from China, semiconductor manufacturers ranked the shortage at 9 out of 10 in severity.

The third is laser technology. Yttrium aluminum garnet — YAG — is the crystal host in the Nd:YAG laser, one of the most widely deployed solid-state lasers in the world. YAG lasers are used in precision manufacturing, laser welding, medical surgery (ophthalmology, dermatology, oncology), military targeting and range-finding, and missile defense systems. The “Y” in YAG is yttrium.

The fourth is high-temperature superconductors. YBCO — yttrium barium copper oxide — is the foundational material for second-generation high-temperature superconducting tape, the same REBCO technology that Commonwealth Fusion Systems is using to build the magnets for SPARC. The “Y” in YBCO is yttrium. The fusion energy timeline depends, in part, on yttrium supply.

The fifth is phosphors and ceramics — LED lighting, display technologies, fiber optic signal amplifiers, and high-performance ceramics for aerospace structural components.

Five sectors. One element. Ninety-nine percent of global production from one country.

Why 99%

Yttrium is recovered primarily from the same ion-adsorption clay deposits in southern China and Myanmar that produce terbium and dysprosium. It is never mined on its own — it’s a co-product of heavy rare earth separation, produced alongside the other heavies as yttrium oxide. China controls over 90% of yttrium mining and approximately 99% of yttrium separation and refining. The U.S. Geological Survey confirmed in January 2025 that the United States produces zero yttrium domestically. One hundred percent is imported. Ninety-three percent directly from China. The remaining 7% from material first processed in China and re-exported through intermediaries.

The concentration is the most extreme in the entire Rare Earth Elements course — higher than antimony (48% mining, 74% refining), higher than gallium (98% refining), higher than terbium (98% refining). At 99% of separation capacity, there is functionally no market outside China. When Beijing issues an export license requirement, it doesn’t restrict the market — it becomes the market.

The dual-price world

The 4,400% European price spike created a dual-price system unlike anything in modern commodity markets. Yttrium oxide at $270 per kilogram in Europe. Yttrium oxide at $7 per kilogram in China. Same product, same purity specification, separated by an export licensing regime. Chinese consumers — aerospace manufacturers, semiconductor equipment producers, laser companies — continued to purchase yttrium at essentially pre-control prices. Western consumers paid 40 times more, if they could source material at all. The antimony and gallium/germanium export controls created dual-price systems with 2-6x differentials. Yttrium’s 40x differential is in a category of its own — a spread so large that it functions less like a trade restriction and more like an economic embargo with Chinese characteristics.

The differential gives Chinese manufacturers a structural cost advantage in every industry that uses yttrium. A Chinese jet engine manufacturer pays $7 per kilogram for yttrium oxide coatings. A Western manufacturer pays $270. A Chinese semiconductor equipment maker pays $7 for chamber linings. A Western fab pays $270. The cost advantage compounds across every product that yttrium touches, and it compounds with the cost advantages China already holds from terbium and samarium price differentials in the magnet supply chain and nickel price advantages from Indonesian smelting.

What comes next

Lynas Rare Earths’ Malaysian separation facility is the only non-Chinese heavy rare earth separator operating at commercial scale, and it has begun producing separated yttrium oxide as of early 2026 — but at initial volumes that are a fraction of global demand. MP Materials’ Mountain Pass mine in California produces light rare earths with minimal yttrium content. New projects in Australia, South Africa, Brazil, and Scandinavia are in various stages of development, but as Benchmark Mineral Intelligence noted, the technology for heavy rare earth refining outside of China is not expected to be globally available until 2029, and costs remain 5-7 times higher than Chinese facilities. The structural gap — between what the West needs and what the West can produce — is a 3-year window at minimum, and the industries on the other side of that window (aerospace, semiconductors, energy, defense) cannot wait three years.

The November 2025 Xi-Trump agreement suspended some of the expanded October 2025 controls for one year until November 2026. The April controls remain in force. The licensing infrastructure remains at Beijing’s discretion. The 99% concentration hasn’t changed. And qualification cycles for alternative yttrium oxide coatings in jet engines are measured in years, not months — introducing a new thermal barrier coating chemistry requires rig testing, engine endurance trials, materials characterization under simulated decades of service, and regulatory approval from aviation authorities, leasing companies, and airlines. Even if alternative coatings existed today, the certification pipeline to deploy them in commercial engines extends into 2027 or later.

Why it’s in the course

Yttrium is the Rare Earth Elements course’s most acute case study of what happens when 99% concentration meets export controls. The CHIPS Act was designed to strengthen the semiconductor supply chain. Yttrium coats the inside of the machines the CHIPS Act is trying to bring onshore. The rhenium post documented the superalloy inside the turbine blade. Yttrium is the coating that protects it. The fusion companies post documented CFS’s REBCO magnets. Yttrium is the “Y” in the YBCO superconducting tape those magnets are wound from. Every high-priority technology the West is investing in — advanced chips, jet engines, fusion energy, missile defense — runs through the same 99% chokepoint.

This is the kind of supply chain our Rare Earth Elements course was built to map — where a 4,400% price spike in eleven months revealed that an element most people have never heard of coats the inside of every chip etching chamber, protects every jet engine turbine blade, forms the crystal in every YAG laser, and constitutes the “Y” in the superconducting tape the fusion industry is betting on — and 99% of its refining capacity is controlled by one country that has already demonstrated, across a half-dozen minerals, exactly what it does with that kind of leverage.
Tantalum: The Conflict Mineral Inside Every Phone You’ve Ever Owned

In February 2026, landslides collapsed several artisanal coltan mines near Rubaya in North Kivu province, eastern Democratic Republic of Congo. At least 227 miners were killed. The Rubaya mines are controlled by M23 — a rebel militia backed by Rwanda and Uganda — which seized the site in 2024 and generates an estimated $800,000 per month from mineral extraction to fund its insurgency. UN experts report that more than 120 tonnes of coltan are transported monthly from the DRC into Rwanda, where it is laundered and exported as Rwandan product to smelters in China, Europe, and the United States. The coltan is processed into tantalum — a heat-resistant metal with a melting point of 3,290°C — and manufactured into the tiny capacitors inside every smartphone, laptop, game console, medical pacemaker, and automotive control unit on the planet. A single smartphone contains 30 to 60 milligrams of tantalum. With 1.2 billion smartphones shipped annually, that single application consumes 36 to 72 metric tonnes — roughly 5% of total global production. In December 2024, the DRC filed an unprecedented legal case against Apple, accusing its Belgian and French subsidiaries of using conflict minerals that fuel violence in eastern Congo. Apple reported $112 billion in net profits that year. The tantalum in one of its phones is worth a few dollars.

What tantalum does

Tantalum’s industrial value comes from a combination of properties that no other element replicates at the same scale and cost. A melting point of 3,290°C — exceeded only by tungsten and rhenium. Exceptional corrosion resistance — tantalum is virtually inert to hydrochloric acid, sulfuric acid, and most organic acids below 150°C, which is why it lines chemical processing equipment and surgical implants. And the property that makes it indispensable to the electronics industry: tantalum forms a thin, stable oxide layer that functions as an extraordinarily effective dielectric, enabling capacitors that are smaller, more reliable, and more thermally stable than any alternative.

Tantalum capacitors operate at temperatures exceeding 200°C, making them essential for processors, memory modules, and power management circuits in smartphones, laptops, data centers, and automotive electronics. They are the reason modern electronics can be as small as they are — the capacitor that regulates voltage in your phone’s processor is a tantalum component measured in fractions of a millimeter. Beyond electronics: tantalum is alloyed into nickel-based superalloys for jet engine turbine blades (the same high-temperature aerospace applications where rhenium and samarium cobalt magnets operate), used in armor-piercing military projectiles, and deployed in surgical implants — hip replacements, cranial plates, wire sutures — because the human body does not reject it.

Where it comes from

The DRC leads global tantalum production, accounting for over 37% of the world’s output. Rwanda is second. Brazil third at 22%. Australia, which once dominated production, has largely withdrawn — its largest mine, Wodgina, shifted to lithium spodumene production when lithium prices made the conversion economically irresistible. Artisanal and small-scale mining collectively accounts for an estimated 64% of global tantalum production — the highest artisanal proportion of any critical mineral in the Rare Earth Elements course.

The DRC-Rwanda corridor is the supply chain’s defining feature and its deepest problem. North Kivu province contains an estimated 80% of the DRC’s coltan reserves, making it a strategic chokepoint for global tantalum supply. The Rubaya area alone accounts for roughly 15% of global coltan output. M23 and approximately 10,000 Rwandan troops control the extraction, trade, and smuggling of minerals from Rubaya. Artisanal miners — approximately 40,000 in the broader North Kivu region — earn $3-5 per day extracting material worth hundreds of dollars per kilogram on international markets. The ore is carried across the border into Rwanda, where it enters the legitimate supply chain as “Rwandan production.” Rwanda’s mineral export revenues tripled from $373 million in 2017 to over $1.75 billion in 2024 — a growth rate that, as multiple UN investigations have noted, far exceeds what Rwanda’s domestic mineral deposits could plausibly explain.

The laundering operation is structurally identical to the commodity-laundering schemes the Shadowcraft course documents across multiple case studies — Marc Rich moving sanctioned oil through shell companies, BCCI moving funds through layered accounts, Mossack Fonseca providing the corporate shells. The DRC coltan trade uses Rwanda as its laundering jurisdiction: conflict-origin ore enters Rwanda, is relabeled as Rwandan production, is exported to smelters in China and Southeast Asia, is processed into tantalum powder, is manufactured into capacitors by KEMET, Vishay, AVX, and other component manufacturers, and appears in the products of Apple, Samsung, Intel, and every other electronics company on Earth. The supply chain has 6-8 intermediary steps between the mine where 227 people died in February 2026 and the phone in your pocket.

The compliance architecture

The global response to tantalum’s conflict mineral status has produced one of the most elaborate compliance frameworks in the critical minerals landscape — and one of the least effective at changing what happens on the ground.

The 2010 Dodd-Frank Act, Section 1502, required U.S.-listed companies to audit their supply chains and report to the SEC whether their products contained tin, tantalum, tungsten, or gold — the “3TG” conflict minerals — sourced from the DRC or adjoining countries. The EU’s Conflict Minerals Regulation, effective since 2021, requires importers of 3TG to conduct due diligence on their supply chains. The OECD Due Diligence Guidance provides the international framework. Smelters can be audited and certified as “conflict-free” through the Responsible Minerals Initiative’s Responsible Minerals Assurance Process. Intel publicly committed to conflict-free processors in 2012 and conducted third-party audits of all its smelters. KEMET, the world’s largest tantalum capacitor manufacturer, established a “closed-pipe” supply chain from its Kisengo mine in Katanga province to its processing plant in Matamoros, Mexico.

The compliance infrastructure exists. The conflict minerals trade continues. M23 controls Rubaya. Rwanda launders the output. Smelters in China process ore whose chain of custody is, in many cases, impossible to verify. The Dodd-Frank reporting requirement was weakened under the Trump administration in 2017. The compliance adds 2-8% to project budgets, which legitimate operators absorb and conflict operators avoid. The structural problem is that tantalum from Rubaya is chemically identical to tantalum from Brazil — once it’s been smelted, no analytical technique can distinguish conflict-origin metal from certified-clean metal. The compliance framework is built on paperwork. The laundering operation is built on chemistry.

Why it’s in the course

Tantalum is the Rare Earth Elements course’s most direct intersection of critical minerals, armed conflict, and consumer electronics. The cobalt/coltan post introduced the conflict minerals framework across the DRC’s mineral economy. This post goes deeper on a single element — the one where the mine-to-phone supply chain is most documented, most laundered, and most directly connected to an active military conflict funded by the mineral itself.

The antimony supply chain vulnerability is about Chinese export controls. The terbium supply chain vulnerability is about Chinese separation monopoly. The nickel supply chain vulnerability is about Indonesian resource nationalism. Tantalum’s vulnerability is different from all of those: 64% of global production is artisanal, a significant fraction is controlled by an armed rebel group, the laundering infrastructure has been documented by UN investigators for two decades, and the compliance framework designed to address it cannot distinguish clean metal from conflict metal once it’s been smelted. The supply chain isn’t concentrated in one country the way gallium or graphite is. It’s concentrated in one conflict zone, with one laundering corridor, funding one war — and the metal that comes out the other end is inside the device you’re reading this on.

This is the kind of supply chain our Rare Earth Elements course was built to map — where a capacitor smaller than a grain of rice depends on a metal mined by hand in a war zone, laundered through a neighboring country, smelted into anonymity, and soldered into 1.2 billion phones a year by companies whose compliance paperwork says the supply chain is clean.
Samarium: The Cold War Magnet the Pentagon Can’t Get Anymore

Samarium cobalt magnets were the original high-performance permanent magnet — the technology that made precision-guided missiles, satellite attitude control, and miniaturized radar possible during the 1970s and 1980s. Then neodymium-iron-boron magnets arrived in 1984, offered stronger fields at lower cost, and samarium cobalt was demoted to a niche material for applications where NdFeB couldn’t survive: environments above 300°C, corrosive atmospheres, radiation exposure, and systems where demagnetization from temperature cycling would be mission-fatal. Fighter jet engine accessories. Missile fin actuators. Traveling wave tubes in military radar. Naval sonar transducers. Satellite reaction wheels. The applications are small in volume and enormous in consequence. Samarium cobalt accounts for less than 2% of global permanent magnet production. It is irreplaceable in systems where failure means a missile doesn’t steer, a radar doesn’t function, or a submarine doesn’t hear. And as of April 4, 2025, China placed samarium — along with terbium, dysprosium, and four other rare earths — under export controls that have effectively halted the reliable flow of SmCo magnets to Western defense contractors.

What makes SmCo different

SmCo magnets come in two grades: SmCo5 (samarium-cobalt 1:5) and Sm₂Co₁₇ (samarium-cobalt 2:17). Both offer thermal stability that NdFeB cannot match. NdFeB magnets start losing their magnetic properties above 80°C without terbium or dysprosium additives, and even with additives, they max out around 200°C. SmCo magnets operate at 250-350°C with no additives and no performance degradation. They resist corrosion without the nickel-copper-nickel plating that NdFeB requires. They’re immune to radiation damage at levels that would demagnetize NdFeB. The tradeoff is energy density — NdFeB magnets produce stronger fields per unit volume — and cost, because both samarium and cobalt are expensive relative to neodymium and iron.

For commercial EV motors and wind turbines, NdFeB wins on performance per dollar. For a missile guidance system operating in an engine bay at 300°C where corrosion resistance matters and magnetic stability is non-negotiable, SmCo is the only option. That division of labor — NdFeB for the clean-energy economy, SmCo for the defense industrial base — is what makes the April 2025 export controls particularly consequential. The Battlefields of the Future course covers how modern weapons systems depend on precision components. SmCo magnets are among the most precision-critical and least substitutable of those components.

The supply chain that doesn’t exist outside China

China refines approximately 90% of the world’s samarium. SmCo magnet manufacturing is concentrated in China because the entire rare earth separation and metal refining supply chain is concentrated in China. When Arnold Magnetic Technologies — one of the few Western SmCo manufacturers, with facilities in the United States, Switzerland, and Thailand — received the April 4 export control announcement, their Chief Commercial Officer noted they had already secured more than a year’s worth of samarium metal inventory. Arnold has since built a non-Chinese samarium and cobalt supply chain to feed its Swiss and Thai manufacturing. That makes Arnold an exception. Most Western magnet buyers are not exceptions.

The Western alternatives that exist are narrower than the headlines suggest. Lynas Rare Earths announced in March 2026 that it had produced the first separated samarium oxide at its Malaysian facility — the first non-Chinese samarium separation in commercial history. The milestone is genuine but the scale is small. Solvay holds a legacy stockpile of roughly 200 tonnes of samarium nitrate in France — material that is finite, already spoken for by defense programs, and not a flowing supply. The Samarium Magnet Company, a Saudi Arabia-based manufacturer, has positioned itself as a non-Chinese alternative with Gulf-region and African rare earth sourcing — but it is a single facility serving a global demand that Chinese producers had supplied for decades. Energy Fuels in Colorado is exploring rare earth separation using uranium processing infrastructure, but is not producing samarium at commercial scale.

The NDAA Section 870 deadline compounds the pressure. Effective January 1, 2027, the U.S. Department of Defense will prohibit the acquisition of samarium cobalt and NdFeB magnets that are mined, refined, melted, or produced in China, Russia, Iran, or North Korea. Defense contractors who have been purchasing Chinese-origin SmCo magnets — which, until April 2025, was the only way to purchase SmCo magnets in meaningful volume — have roughly eight months from this writing to secure NDAA-compliant supply chains. Arnold has one. Lynas has started producing samarium oxide. Everyone else is scrambling.

The April 2025 controls in practice

The export control process has been worse than the export control announcement. MOFCOM’s April 2025 Announcement No. 18 required export licenses for samarium, SmCo magnets, and SmCo alloys. Provincial commerce bureaus initially communicated 45-60 day review windows. Actual processing times have exceeded those estimates consistently. By mid-2025, Arnold reported that “military-adjacent, aerospace, and sophisticated sensor programs almost never receive approvals.” Commercial applications face intense scrutiny of end-use declarations, and licenses are issued on a per-shipment basis — even identical repeat orders require separate license applications.

The practical consequence is that Western companies cannot plan production around Chinese SmCo supply. A magnet manufacturer outside China that had legally purchased samarium earlier in 2025 was contractually required to block shipment of finished SmCo ingots after the October controls expanded to cover Chinese-origin minerals used in dual-use applications — even though the alloy was manufactured and processed entirely outside China. The extraterritorial reach is the same mechanism the terbium post documented: China asserts licensing authority over products containing Chinese-origin rare earth inputs at concentrations as low as 0.1%, regardless of where the product is manufactured. The semiconductor supply chain has ASML’s export restrictions limiting Chinese access to EUV lithography. China’s rare earth export controls are the mirror image: limiting Western access to the materials that go inside the machines.

The cobalt complication adds a second layer of supply risk. Cobalt constitutes roughly 30% of SmCo alloy by mass, and cobalt supply is concentrated in the DRC, where artisanal mining, conflict, and price volatility create their own supply chain constraints. SmCo magnet manufacturers face simultaneous pressure on both inputs: samarium from Chinese export controls and cobalt from DRC supply instability. The intersection of those two constraints — one geopolitical, one geological — is what makes SmCo the most supply-constrained magnet technology in the world.

The comeback nobody wanted

The irony of samarium’s 2025-2026 resurgence is that nobody in the magnet industry wanted it. NdFeB was supposed to be the permanent magnet of the future — cheaper, stronger, increasingly available from non-Chinese sources as MP Materials and Lynas expanded light rare earth production. SmCo was the legacy technology, maintained for defense applications where nothing else would do but otherwise declining in commercial relevance. Then China put samarium, terbium, and dysprosium under export controls in the same announcement, and the magnet industry discovered that both its leading-edge technology (high-temperature NdFeB with terbium/dysprosium) and its legacy fallback (SmCo) were simultaneously supply-constrained by the same country’s export licensing regime. The diversification that was supposed to protect the supply chain — “we’ll use NdFeB for commercial and SmCo for defense” — turned out to be diversification within a single point of failure.

The gallium/germanium controls in 2023 restricted semiconductor feedstock. The antimony controls in 2024 restricted ammunition and flame retardant materials. The graphite controls in 2023 restricted battery anode materials. The April 2025 rare earth controls restricted the magnets that go into everything — EVs, wind turbines, guided missiles, radar, sonar, MRI machines, industrial robots, and the semiconductor lithography equipment that SmCo magnets sit inside. Each escalation in the sequence has targeted a higher-value, harder-to-substitute category of material. Samarium is the escalation that reached the defense industrial base.

This is the kind of supply chain our Rare Earth Elements course was built to map — where a magnet technology the West invented in the 1970s, let China monopolize in the 2000s, and assumed would always be available as a commodity, became in April 2025 the most restricted defense-critical material on the export control list, with eight months left before U.S. law prohibits the Pentagon from buying it from the only country that produces it at scale.
Terbium: The Bottleneck Inside the Bottleneck

On April 4, 2025, China imposed export controls on seven heavy rare earth elements — samarium, gadolinium, terbium, dysprosium, lutetium, scandium, and yttrium — along with their compounds, metals, alloys, and any magnets containing them. On October 9, 2025, Beijing expanded the controls to include holmium, erbium, thulium, ytterbium, and — critically — “parts, components, and assemblies” containing any of these materials, including products manufactured outside China using Chinese-sourced inputs at concentrations as low as 0.1%. The controls were suspended on November 7, 2025, as part of the Xi-Trump trade agreement, for one year until November 2026. They are, as of this writing, frozen — not withdrawn. Before the suspension, European dysprosium oxide prices reached $900 per kilogram, roughly triple the Chinese domestic price of $255. Terbium oxide was trading at levels that caused suppliers to halt sales to private investors entirely, prioritizing industrial customers. The CEO of Germany’s Vacuumschmelze — one of the few rare earth magnet manufacturers outside China — told Reuters in November 2025: “If you talk about critical resources, it’s really the heavies, the heavies, the heavies — all the rest we will get.” He was talking about terbium and dysprosium. And he was right.

What terbium does

Terbium is a heavy rare earth element — atomic number 65 — and its industrial importance is almost entirely about magnets. Neodymium-iron-boron permanent magnets are the most powerful permanent magnets in existence, used in every EV traction motor, every direct-drive wind turbine generator, every hard disk drive, every guided missile, every MRI machine, and most industrial robots. The problem with NdFeB magnets is that they lose their magnetic properties at elevated temperatures — above roughly 80°C, an NdFeB magnet begins to demagnetize. An EV motor operating under sustained load, a wind turbine nacelle in summer heat, a fighter jet engine bay — all exceed that threshold. Adding small quantities of terbium or dysprosium to the alloy extends the operating temperature range to 200°C or higher. The addition is small — a few percent by weight — but the effect is the difference between a magnet that works in a laboratory and a magnet that works in a car.

Terbium is the more effective of the two heavy rare earth additives — it provides stronger coercivity enhancement per unit of concentration than dysprosium — but it’s also rarer and more expensive. In practice, magnet manufacturers use both, often in combination, depending on the application’s thermal requirements and the relative cost and availability of each. For the highest-performance applications — military systems, aerospace actuators, precision guidance systems — terbium is preferred. For lower-temperature applications, dysprosium suffices.

Beyond magnets, terbium has a secondary role in phosphors — it emits a vivid green light when excited, which made it essential for color television, fluorescent lighting, and trichromatic display systems. LED technology has largely displaced fluorescent phosphors, but terbium-based phosphors remain relevant in medical imaging, scientific instruments, and specialized displays. Terbium is also the primary component of Terfenol-D — an alloy of terbium, dysprosium, and iron that exhibits the strongest magnetostriction of any known material, meaning it physically expands and contracts in response to magnetic fields. Terfenol-D is used in naval sonar transducers, precision actuators, and vibration sensors. A submarine’s ability to detect other vessels depends, in part, on terbium.

Where 98% comes from

China controls over 90% of refined terbium supply. The highest-grade commercial deposits are ion-adsorption clays in southern China — Jiangxi, Guangdong, Fujian — where heavy rare earths are adsorbed onto clay particles and extracted by leaching with ammonium sulfate. A ton of clay yields a few hundred grams of mixed rare earth oxides, of which terbium might constitute a few grams. The extraction is low-tech, environmentally destructive (the leaching process contaminates groundwater and strips hillsides), and labor-intensive — but the deposits are uniquely rich in the heavy rare earths the magnet industry needs.

Myanmar has become the second most important source of heavy rare earth ore — mined primarily in the Kachin and Wa states by ethnic militias operating in a civil war zone, shipped across the Chinese border, and processed in Chinese separation facilities. The ore flows through a corridor that China effectively controls on both ends: the armed groups who mine it depend on Chinese buyers, and the separation capacity that converts raw ore into usable oxide is 98-99% concentrated in China. Conflict minerals is a term usually applied to the DRC’s cobalt and coltan supply chains. The Myanmar heavy rare earth trade has the same structural characteristics — extraction in a conflict zone, processing controlled by an external power, and end-use in consumer products whose buyers rarely ask where the material came from.

The West has deposits but not capacity. MP Materials’ Mountain Pass mine in California produces light rare earths — neodymium and praseodymium — but contains only traces of terbium and dysprosium. Lynas Rare Earths in Australia began heavy rare earth separation in Malaysia in 2025, becoming the first non-Chinese heavy rare earth separator on Earth — but at initial volumes of roughly 250 tonnes of dysprosium and 50 tonnes of terbium per year, it’s a fraction of global demand. Energy Fuels, a Denver-based uranium miner, is pivoting to rare earth separation using similar process chemistry — but is not yet producing at scale. Brazil is emerging as an ore exporter, but as Benchmark Mineral Intelligence noted, “the technology for HREE refining is expected to be available globally by 2029” and “costs outside of China remain 5-7 times higher.” The problem is not that heavy rare earth deposits don’t exist outside China. The problem is that the separation and refining capacity to convert those deposits into usable materials is, as of 2026, a Chinese monopoly with a few early-stage Western competitors years away from meaningful scale.

The April 2025 export controls

The April 2025 controls followed the same escalation pattern the Rare Earth Elements course has documented across gallium/germanium (July 2023), graphite (October 2023), antimony (August 2024), and tungsten (early 2025) — but with a crucial escalation. The earlier controls restricted raw materials and processed forms. The April 2025 controls restricted magnets containing terbium and dysprosium — finished products, not just feedstock. The October 2025 expansion went further: it applied extraterritorial jurisdiction to “parts, components, and assemblies” containing Chinese-sourced rare earth materials, even if manufactured outside China, even if traded domestically in a third country. A European carmaker using a motor containing a magnet with 0.1% Chinese-origin terbium would, under the October rules, need a Chinese export license for the motor — not for the terbium, for the motor.

The IEA reported that after the April controls took effect, “many carmakers in the United States, Europe, and elsewhere struggled to obtain permanent magnets, with some forced to cut utilisation rates or even temporarily shut down factories.” European rare earth prices reached up to six times Chinese domestic prices. The November 2025 suspension froze the escalation but did not reverse it. The controls remain on the books. The licenses remain at Beijing’s discretion. The semiconductor supply chain has TSMC in Taiwan. The lithium supply chain has Chinese refining. The magnet rare earth supply chain has something worse: Chinese separation capacity so dominant that the export controls don’t just restrict supply — they assert jurisdiction over finished products manufactured anywhere in the world using Chinese-origin inputs. That’s not a trade restriction. That’s extraterritorial industrial policy.

Why terbium is the real bottleneck

McKinsey projects global demand for magnet rare earths will triple from 59,000 tonnes in 2022 to roughly 176,000 tonnes by 2035. Under rapid clean-energy adoption scenarios, terbium requirements could reach 134-256% of available supply — meaning the energy transition needs one-and-a-half to two-and-a-half times more terbium than the planet currently produces. The EU projects that demand for rare earth magnets could increase tenfold by 2050. The projected 60,000-tonne shortfall by 2035 — approximately 30% of total requirements — is concentrated in the heavy rare earths, not the lights. Neodymium and praseodymium can be sourced from Mountain Pass, from Lynas, from emerging projects in Brazil and Africa. Terbium and dysprosium cannot — not at the volumes the market needs, not at processing costs the market can absorb, and not from facilities that currently exist outside Chinese control.

Every EV motor, every wind turbine, every humanoid robot actuator, every military guidance system that requires a high-temperature permanent magnet runs into the same constraint: the heavy rare earths that make the magnet work at temperature come from one country, are separated in one country, and are now subject to export controls that assert jurisdiction over products made in every other country. The nickel supply chain was restructured by Indonesian resource nationalism in five years. The terbium supply chain was never diversified enough to restructure — it started concentrated and stayed concentrated, and the concentration is now being weaponized.

This is the kind of supply chain our Rare Earth Elements course was built to map — where the element that allows an EV motor magnet to survive operating temperature is separated from clay in southern China and a civil war zone in Myanmar, refined in facilities that are 98% Chinese-controlled, subject to export controls with extraterritorial reach, and projected to be in deficit by 2035 under every growth scenario the energy transition requires.
Rhenium: The Rarest Metal in Your Jet Engine

Global rhenium production in 2024 was approximately 62,000 kilograms — 62 tonnes. That’s it. The entire world’s annual output of the metal that allows jet engines to operate at 1,700 degrees Celsius without the turbine blades melting would fit inside two shipping containers. Rhenium prices rose 91.5% in 2025, then added another 34% in the first quarter of 2026, reaching roughly $2,400 per kilogram in Europe. The price action isn’t speculative froth — it’s a structurally tiny market absorbing the largest commercial aviation production ramp-up in history. Boeing and Airbus have combined backlogs of more than 15,000 aircraft. Each wide-body jet engine contains several kilograms of rhenium concentrated in the turbine blades that spin at 40,000 RPM in exhaust gas temperatures that would liquefy any unalloyed metal on the periodic table. A single company — Molymet S.A. in Chile — controls 60% of global rhenium production. Rhenium has no primary mine anywhere on Earth. It is recovered exclusively as a by-product of molybdenum roasting, which is itself a by-product of copper mining. The by-product supply ceiling that constrains indium, tellurium, and the noble gases applies here in its most extreme form: rhenium is a by-product of a by-product. Two layers of someone else’s business model between you and the metal your jet engine needs.

What rhenium does

Rhenium has the third-highest melting point of any naturally occurring element — 3,186°C — and the highest boiling point of all. When alloyed with nickel at 2-6% by weight, it forms single-crystal superalloys — materials like CMSX-4 and René N5 — that retain their structural integrity under the combination of extreme heat, extreme mechanical stress, and corrosive combustion gases that exist inside a jet engine’s high-pressure turbine section. Without rhenium, turbine blades deform under the sustained loading at operating temperature — a failure mode called creep — and the engine loses efficiency, thrust, and eventually structural integrity. The addition of rhenium doesn’t just improve performance. It makes the performance possible. Modern high-bypass turbofan engines like the GE9X (which powers the Boeing 777X) and the Rolls-Royce Trent XWB (which powers the Airbus A350) were designed around rhenium-containing superalloys. You cannot substitute the rhenium out of these engines without redesigning the turbine, recertifying the engine, and accepting lower operating temperatures that reduce fuel efficiency — a process that takes years of testing and hundreds of millions of dollars in development cost.

Roughly 80% of global rhenium consumption goes into aerospace superalloys. The remaining 20% splits between petroleum refining catalysts — rhenium-platinum catalysts are essential for producing high-octane lead-free gasoline — and a growing list of niche applications including medical isotopes (rhenium-186 and rhenium-188 for cancer therapy), radiation shielding, and high-precision surgical instruments.

The double by-product problem

The rhenium supply chain is the purest expression of the by-product constraint the Rare Earth Elements course has been documenting across indium/tellurium, noble gases, and iridium within the PGM complex. But rhenium adds a layer of complexity the others don’t have.

Copper is mined from porphyry deposits in Chile, the United States, Peru, and Kazakhstan. Some of those copper ores contain molybdenite — a molybdenum sulfide mineral — which is recovered as a by-product of copper processing. The molybdenite concentrate is then roasted to produce molybdenum trioxide, and during that roasting process, rhenium volatilizes out of the concentrate as rhenium heptoxide in the flue gas. Specialized scrubbers in the roasting facility’s exhaust system capture the rhenium. If the scrubbers aren’t installed, or aren’t optimized for rhenium recovery, the rhenium exits the smokestack and disperses into the atmosphere. Gone.

Chile produced 29,000 kilograms of rhenium in 2024 — nearly half the global total — because Chile has the world’s largest copper-molybdenum porphyry deposits (Escondida, Chuquicamata, El Teniente) and because Molymet, the Santiago-based molybdenum processor, installed rhenium recovery equipment decades ago and has since acquired downstream processing capacity including Rhenium Alloys in Ohio, now operating as Molymet Alloys USA. The United States produced 9,500 kg, mostly from Freeport-McMoRan’s copper-molybdenum operations in Arizona and New Mexico. Poland produced 9,400 kg from KGHM’s copper operations. China produced 5,300 kg. The entire rest of the world produced the remainder.

The structural constraint is identical to indium’s but twice compounded: if the world needs more rhenium, it needs more molybdenum roasting capacity with rhenium recovery equipment installed, which requires more molybdenum concentrate, which requires more copper mining. The decision to expand copper production is made by copper companies based on copper economics. The decision to install rhenium scrubbers is made by molybdenum processors based on rhenium prices relative to scrubber capital costs. At each layer, the entity making the production decision is optimizing for a different metal than the one the aerospace industry needs. Supply elasticity is, in the language of the economics textbooks, structurally constrained. In the language of the Battlefields of the Future course: the fighter jet’s turbine blade depends on a molybdenum roaster in Chile deciding the flue gas scrubber is worth the investment.

The aerospace bottleneck

The demand side of the rhenium market is defined by a single fact: the global aviation industry is attempting the largest production ramp-up in its history, and every new engine needs rhenium. The pandemic cleared factory floors, grounded aircraft, and delayed maintenance cycles. The recovery has produced backlogs that will take a decade to work through. Every widebody engine, every military fighter jet engine, every industrial gas turbine that uses rhenium-containing superalloys draws from a 62-tonne global pool. Demand is projected to grow at 2.1% annually through 2034 — a modest growth rate in percentage terms, but applied to a base so small that even modest demand growth tightens supply.

Turbine blades have 15-to-25-year service lives before they’re retired and recycled. The recycling rate for rhenium from spent superalloys and foundry revert material is 25-50% — significantly better than most critical minerals but constrained by long collection cycles and the capital intensity of superalloy recycling. GE Aerospace and Rolls-Royce have both established closed-loop product stewardship programs to recover rhenium from spent blades. The rare earth recycling infrastructure the course has documented is nascent for most minerals. For rhenium, it’s more mature — but still limited by the physics of 15-year wait times between engine installation and blade retirement.

GE and Rolls-Royce have also invested in “rhenium-lean” and “rhenium-free” superalloy formulations using combinations of ruthenium, tantalum, hafnium, tungsten, and molybdenum. Some newer engine designs have successfully reduced rhenium loading. But the installed fleet and the engines currently in production were designed around rhenium-containing alloys, and redesigning a turbine blade is not a materials-substitution exercise you complete in a quarter. Each new alloy formulation requires years of creep testing, oxidation testing, fatigue testing, engine testing, and FAA certification before it can be deployed in a commercial aircraft. The semiconductor supply chain can redesign a chip in 18 months. A turbine blade alloy substitution takes a decade.

Why it’s in the course

Rhenium is the Rare Earth Elements course’s most extreme case study of by-product dependency — and the one that connects the critical minerals thesis directly to the aerospace and defense industrial base. The antimony post documented a mineral whose supply was disrupted by deliberate export controls. The nickel post documented a market restructured by deliberate resource nationalism. The noble gases post documented a supply chain that concentrated by accident and broke because of a war. Rhenium is none of those things. Rhenium’s supply constraint is the most permanent kind: the element is genuinely one of the rarest on Earth — 1 part per billion in the crust, rarer than gold, rarer than platinum, rarer than all but a handful of stable elements — and it can only be obtained as a by-product of a by-product, from mines built for a different purpose, processed by companies optimizing for a different metal, at volumes that cannot be meaningfully increased without expanding copper mining globally.

The lithium supply chain has a demand problem — consumption is growing faster than supply can respond. The copper supply chain has a capacity problem — there aren’t enough mines being built. Rhenium has a physics problem. There is no rhenium mine to build. There is no rhenium deposit to discover. There is only the copper-molybdenum system, the flue gas, the scrubber, and the 62 tonnes per year that represents the ceiling the aerospace industry is building its production ramp-up under.

This is the kind of supply chain our Rare Earth Elements course was built to map — where the metal that allows a turbine blade to survive 1,700 degrees at 40,000 RPM is recovered from the smokestack exhaust of a molybdenum roaster in Santiago, at 62 tonnes a year, with a single company controlling 60% of global output, and the entire commercial aviation industry’s production backlog competing for every gram.
Neon, Krypton, and Xenon: The Invisible Gases That Make Every Chip on Earth

On February 24, 2022, Russia invaded Ukraine. Within days, two companies in Odessa and Mariupol — Cryoin and Ingas — shut down their operations. Together, they had been producing roughly 50% of the world’s semiconductor-grade neon. Ukraine as a whole supplied approximately 70% of global neon, 40% of krypton, and 25-30% of xenon — the three noble gases that power the lasers used to etch circuits onto every advanced semiconductor chip manufactured on the planet. Neon prices in China rose tenfold within weeks. Krypton prices in Japan quadrupled. Xenon, which had traded at $15 per liter in 2020, spiked above $100. The world’s most sophisticated industry — semiconductor fabrication — discovered that it was dependent on gases captured from Soviet-era steel mills in a war zone, purified by two mid-sized companies in cities that were being bombed. The concentration wasn’t the result of geological scarcity. Neon, krypton, and xenon exist everywhere — they’re in the air you’re breathing right now. The concentration was an accident of industrial history, and the fact that the accident had never been corrected in three decades of post-Soviet globalization tells you something about how supply chains actually work: nobody fixes a single point of failure until it fails.

What the gases do

Neon, krypton, and xenon are noble gases — chemically inert elements that don’t react with other materials, which is precisely what makes them useful in environments where contamination would destroy the product.

Neon’s critical application is semiconductor photolithography. The excimer lasers used to etch circuit patterns onto silicon wafers — the deep ultraviolet (DUV) systems that still produce the majority of the world’s chips — use gas mixtures that are approximately 96% neon, with small amounts of argon, krypton, fluorine, or xenon depending on the wavelength required. ArF (argon-fluorine) lasers at 193 nanometers and KrF (krypton-fluorine) lasers at 248 nanometers are the workhorses of the semiconductor industry. Every fab that runs DUV lithography consumes neon. The gas mixtures degrade during use and must be regularly replaced. TSMC, Samsung, Intel, and every other chipmaker on Earth — including the Chinese fabs the CHIPS Act was designed to compete against — need a continuous supply of ultra-high-purity neon to keep their lasers firing.

Krypton serves double duty. In semiconductor manufacturing, it’s a component of the laser gas mixtures. Outside the fab, krypton fills the gap between panes in energy-efficient triple-glazed windows — a growing market as building energy codes tighten globally. It’s also used in high-intensity lighting for airports and stadium illumination.

Xenon has the broadest application portfolio of the three. It’s an anesthetic in medicine — safer than nitrous oxide, with faster recovery times, though dramatically more expensive. It fills the flash tubes in high-end photography equipment. It’s used as a contrast agent in CT imaging. And — increasingly — it fuels the ion propulsion systems on communications satellites and Earth observation spacecraft. SpaceX’s Starlink constellation and Amazon’s Project Kuiper are driving xenon demand as satellite constellations proliferate. When a Starlink satellite adjusts its orbit, it’s expelling ionized xenon. The space economy’s growth curve is, unexpectedly, a noble gas demand curve.

Why Ukraine had 70% of global neon

The answer is Soviet military planning. During the 1970s and 1980s, the Soviet Union treated neon as a strategic material for high-powered laser weapons research — the kind of Cold War physics that the Battlefields of the Future course covers from the other side. Every major air separation unit in the Soviet Union was equipped with neon, krypton, and xenon enrichment facilities. Air separation units produce oxygen — which steel mills need in enormous volumes — and the noble gases are captured as by-products of the oxygen production process. The Soviet Union had massive steel mills. The massive steel mills had massive air separation units. The massive air separation units captured massive quantities of noble gases. When the Soviet Union collapsed, the steel mills ended up in Ukraine — particularly in the industrial cities of the Donbas and Black Sea coast — and the noble gas capture equipment went with them.

For three decades, Ukrainian companies collected these gases, purified them to semiconductor grade (99.999% purity for neon), and exported them to the global chip industry at prices that made building competing production capacity uneconomical anywhere else. The same by-product supply structure that constrains indium and tellurium applies here: neon is a by-product of oxygen production, which is a by-product of steelmaking. You cannot produce more semiconductor-grade neon without operating air separation units at steel mills, and the economics of operating those units are determined by steel demand, not neon demand. Ukraine’s dominance wasn’t because Ukrainian neon was better. It was because Ukrainian steel mills had the gas capture equipment installed, nobody else had bothered to install it, and the resulting supply was cheap enough to discourage competition.

What happened after the shock

The predicted catastrophe — fabs shutting down, chip shortages deepening, economic disaster — largely didn’t materialize. The semiconductor industry responded faster than most analysts expected, for several reasons.

First, the major chipmakers had prepared. After neon prices spiked 600% during the 2014 Crimean annexation, TSMC, Samsung, and others diversified suppliers and built strategic stockpiles. Most large fabs had 3-6 months of gas reserves when the 2022 invasion began.

Second, recycling technology scaled rapidly. Modern DUV scanners can recover and purify over 90% of the neon used in each laser pulse, dramatically reducing virgin neon consumption per wafer. TSMC’s neon recycling program became a model for the industry.

Third, new production came online. Linde had invested $250 million in a neon production facility in La Porte, Texas, after the 2014 scare. Chinese air separation companies expanded noble gas capture. South Korean and Japanese producers increased output. By 2023, the acute shortage had eased. Prices retreated from their peaks. The industry congratulated itself on resilience.

Fourth — and this is the detail that changes the long-term picture — the technology is shifting. ASML’s extreme ultraviolet (EUV) lithography systems, which are required for the most advanced 5-nanometer and 3-nanometer chips, do not use neon. EUV lasers vaporize tin droplets rather than exciting noble gas mixtures. As EUV adoption expands and DUV’s share of leading-edge production declines, neon demand from the semiconductor industry will structurally decrease. The gas that nearly crippled the chip industry in 2022 may become less critical to the chip industry by 2030 — not because the supply chain was fixed, but because the technology moved on.

Where it stands in 2026

The noble gas market in 2026 is more diversified than 2022 but still structurally fragile. Ukrainian production has partially recovered — Cryoin’s Odessa facility has resumed operations, though at reduced capacity, and the Mariupol facilities remain destroyed. China, Japan, South Korea, and the United States have all expanded noble gas production and purification capacity. The acute price crisis is over.

But the underlying architecture hasn’t fundamentally changed. Noble gases remain by-products of air separation at steel mills and industrial gas plants. The decision to capture them — rather than venting them into the atmosphere — is discretionary, driven by the economics of the gas market relative to the cost of operating the capture equipment. When neon was $100 per liter, everyone captured it. At lower prices, the incentive weakens. The antimony supply chain showed that price normalization after a crisis doesn’t mean the structural vulnerability has been resolved — it means the market has priced in the assumption that the crisis won’t recur.

Xenon faces its own emerging constraint. Satellite constellation demand is growing faster than xenon supply. SpaceX’s Starlink alone operates over 6,000 satellites, each requiring xenon for station-keeping maneuvers. Amazon’s Kuiper constellation will add thousands more. If the space economy’s xenon demand outgrows the industrial gas industry’s xenon capture, the same by-product ceiling that constrains indium, tellurium, and iridium will constrain the propellant supply for the satellite industry. SpaceX has already begun testing krypton as a cheaper, more abundant xenon substitute in some Starlink applications — a substitution that trades performance for supply security, and that shifts demand pressure from one noble gas to another rather than relieving it.

Why they share a lecture

Neon, krypton, and xenon are the Rare Earth Elements course’s case study in accidental concentration — the supply chain vulnerability that exists not because of geological scarcity or deliberate resource nationalism, but because of industrial inertia. Nobody cornered the noble gas market. Nobody imposed export controls. The Soviet Union installed gas capture equipment at steel mills for laser weapons research. The equipment ended up in Ukraine. Ukraine supplied the world for thirty years. Then a war started and the supply vanished overnight.

The nickel case is about deliberate resource nationalism — Indonesia’s export ban was a strategic decision. The gallium/germanium and antimony cases are about deliberate export controls — China’s licensing regime is an instrument of state policy. The noble gas case is about none of those things. It’s about a supply chain that concentrated by accident, stayed concentrated through inertia, and broke because of a war that had nothing to do with semiconductors. That’s a different category of supply chain risk — one that no critical minerals policy is designed to prevent, because it’s not the result of any policy at all. It’s the result of nobody looking at the map and asking what happens when the cheapest supplier is in a country that borders Russia.

This is the kind of supply chain our Rare Earth Elements course was built to map — where the gases that power every chip laser on Earth were by-products of Soviet steel mills repurposed for Cold War laser weapons, concentrated in two cities in a war zone, and the industry that needed them only found out when the bombs started falling.
Nickel in 2026: How Indonesia and China Killed a Global Industry

In 2020, Indonesia banned the export of raw nickel ore. Within four years, Indonesia’s share of global nickel production had risen from 31.5% to 60%. At least eight nickel mines in Australia and New Caledonia closed. BHP wrote down $3.5 billion on its Western Australian nickel operations and suspended them. Glencore closed its Koniambo smelter in New Caledonia. The only operating nickel mine in the United States — Eagle Mine in Michigan — is scheduled to close by 2026. Macquarie Group estimates that roughly 250,000 tonnes of annual production has been taken out of the global market by mine closures, with another 190,000 tonnes of planned output delayed. At $18,000 a tonne, 35% of global nickel production is unprofitable. At $15,000, that number jumps to 75%. The mechanism that did this was straightforward: Chinese companies invested roughly $30 billion in Indonesian nickel smelting capacity, using technology that could convert low-grade laterite ore — traditionally too expensive to process — into nickel pig iron and battery-grade nickel at costs that undercut every sulfide mine in the Western world. Indonesia provided the ore and the export ban that forced domestic processing. China provided the capital, the technology, and the smelters. Together, they flooded the global market with cheap nickel, cratered the price, and eliminated the competition. An Indonesian government official reportedly told struggling Western producers not to expect prices above $18,000 a tonne and said the country would ensure the market remains well supplied. The critical minerals supply chain has a new case study in how resource nationalism, backed by Chinese capital, can restructure a global commodity market in under five years.

Why nickel matters

Nickel’s industrial demand splits into two categories that are pulling in opposite directions. The legacy demand — roughly 60% of global consumption — is stainless steel. Nickel alloyed with chromium and iron produces the corrosion-resistant steel used in everything from kitchen sinks to chemical processing tanks to surgical instruments. Stainless steel demand grows with global industrial activity — slowly, predictably, and without the dramatic growth curves that battery metals generate.

The growth demand is EV batteries. Nickel-manganese-cobalt cathodes — NMC — are the dominant battery chemistry in European and Korean electric vehicles, offering higher energy density and longer range than the lithium iron phosphate (LFP) chemistry that dominates in China. A typical NMC battery pack for a long-range EV contains 30 to 50 kilograms of nickel. Higher-nickel formulations — NMC 811, where nickel constitutes 80% of the cathode — reduce the need for expensive cobalt while increasing energy density. The trajectory for years was clear: more nickel per battery, more batteries per year, nickel demand going parabolic.

Then LFP happened. LFP batteries use no nickel and no cobalt. They’re cheaper, safer, last longer, and — with improvements in energy density — increasingly competitive on range. In China, NMC’s share of the EV battery market fell from 25% in 2024 to 18% in the first nine months of 2025. Globally, LFP reached 50% of all EV batteries sold in 2025. The chemistry shift doesn’t eliminate nickel demand from batteries — NMC still dominates in premium vehicles, European production, and applications where energy density justifies the cost premium. But it slows the demand growth rate at exactly the moment Indonesia’s supply surge is flooding the market. The result is a 261,000-tonne surplus projected for 2026, the third consecutive year of oversupply, with LME warehouse inventories at their highest level in more than four years.

How Indonesia did it

Indonesia’s nickel strategy is the most successful example of resource nationalism in the 21st century, and the playbook is worth understanding because it’s being studied by every mineral-rich government on Earth.

Step one: ban the export of raw ore. Indonesia prohibited raw nickel ore exports in January 2020, forcing any company that wanted Indonesian nickel to build processing capacity inside the country. The policy created an immediate incentive for foreign investment in domestic smelters.

Step two: welcome Chinese capital. Tsingshan Holding Group — which produces nearly a third of the world’s stainless steel — built the Indonesia Morowali Industrial Park in Central Sulawesi, a massive complex of nickel pig iron smelters, stainless steel mills, and HPAL (high-pressure acid leach) facilities for battery-grade nickel. CATL, the world’s largest battery manufacturer, is building a mine-to-battery supply chain in North Maluku and a battery plant in West Java. Chinese companies now control approximately 75% of Indonesia’s nickel smelting capacity.

Step three: undercut global competitors. Indonesian NPI production costs are low enough — thanks to cheap local labor, integrated operations, and coal-fired power — that producers remained profitable at price levels that forced Australian, New Caledonian, and Canadian mines into closure. The environmental cost is significant: deforestation of tropical rainforest for laterite mining, acid waste from HPAL processing, coal-powered smelters producing some of the highest-carbon nickel on the market, and tailings management practices that environmental groups have documented as inadequate. The “clean energy” supply chain for EVs runs through one of the dirtiest nickel production systems in the world.

Step four: manage the surplus. By late 2025, Jakarta recognized the oversupply was depressing prices enough to threaten its own producers. The government cut 2026 mining quotas to 260-270 million wet metric tonnes, down roughly 30% from 2025’s 379 million. It shortened quota validity from three years to one year. It banned new NPI smelters and HPAL plants. PT Vale Indonesia temporarily halted mining in January 2026 after failing to secure its quota approval. Tsingshan suspended production lines at Morowali. The government that flooded the market is now trying to drain it — classic OPEC logic applied to nickel.

The class problem

There is a detail the market cares about enormously that most coverage glosses: not all nickel is the same. Class 1 nickel is high-purity metal (99.8%+ nickel content) — the form that can be delivered onto the London Metal Exchange and that battery cathode manufacturers need for NMC production. Class 2 nickel includes nickel pig iron and ferronickel — lower-purity products suitable for stainless steel but not for batteries without additional processing. Indonesia overwhelmingly produces Class 2. The HPAL facilities produce mixed hydroxide precipitate, which can be refined into battery-grade nickel sulfate — but that refining step happens mostly in China.

The class distinction matters because the global nickel surplus is concentrated in Class 2. The Class 1 market is tighter. LME warehouse inventories are rising because Chinese and Indonesian producers are refining excess feedstock into Class 1 metal and dumping it onto the exchange — China’s refined nickel exports are up 55% year-on-year through October 2025. The price signal that the market sends — “there’s too much nickel” — is accurate for stainless steel feedstock and misleading for battery-grade material, where the supply chain still runs through Chinese refining that the CHIPS Act and the Inflation Reduction Act were specifically designed to reduce dependence on.

The Western response

The response has been slow and expensive. Vale is building a nickel sulfate refinery in Bécancour, Québec, with deliveries to General Motors targeted for the second half of 2026. Canada Nickel’s Crawford project in Ontario has Department of Defense funding and Samsung SDI investment. Talon Metals received $20.6 million from the DOD and $115 million from the DOE for a processing plant in North Dakota tied to a copper-nickel project in Minnesota led by a Glencore-Teck joint venture. These are meaningful investments. They are also, collectively, a fraction of the capital China has deployed in Indonesia. The semiconductor supply chain demonstrated that fab construction takes years and billions of dollars. Nickel mine development takes 5-10 years minimum from discovery to production, requires $1-3 billion per project, and — at current prices — struggles to attract financing because Indonesian supply has set a price floor that Western sulfide projects can’t compete with. The free market solution to Indonesian nickel dominance is to build mines that lose money at current prices and hope the market recovers before the capital runs out.

Why it matters

Nickel is the Rare Earth Elements course’s resource nationalism case study — the lecture that shows what happens when a major mineral-producing country decides to capture downstream value rather than exporting raw materials. The antimony and gallium/germanium cases are about export controls — restricting supply as leverage. Indonesia’s nickel strategy is the opposite: flooding supply as leverage, using Chinese-backed processing capacity to undercut competitors, eliminate their mines, and establish a dominant market position that will take a decade to challenge even if prices recover. The ARMSCOR post documents a state that built an arms industry to circumvent an embargo. Indonesia built a nickel industry to circumvent the global cost curve.

The irony of the energy transition’s nickel dependence is structural. Western governments want clean EVs made with responsibly sourced materials. The cheapest nickel on Earth comes from coal-fired smelters processing laterite ore strip-mined from Indonesian rainforest, financed by Chinese capital, refined into battery-grade material in Chinese facilities, and sold to automakers who need it to qualify for IRA subsidies requiring critical minerals sourced from U.S. free trade agreement partners — which Indonesia is not. The lithium supply chain routes through Chinese refining. The graphite supply chain routes through Chinese processing. The nickel supply chain routes through Chinese-built smelters in Indonesia. The vanadium alternative to lithium-ion storage avoids nickel entirely but introduces its own concentration risk. Each solution to one dependency creates another.

This is the kind of supply chain our Rare Earth Elements course was built to map — where a single export ban in 2020 restructured a global commodity market by 2024, eliminated the Western competition by 2025, and left the energy transition dependent on the dirtiest nickel production system on Earth, financed by the country the energy transition’s trade policy was designed to reduce dependence on.
Indium and Tellurium: The By-Product Metals With a Supply Ceiling Nobody Controls

There is a category of critical mineral whose supply cannot be increased by building more mines, raising the price, or passing legislation — because the mineral is not what anyone is mining for. Tellurium is a by-product of copper refining. Indium is a by-product of zinc smelting. Neither has a primary mine anywhere on Earth. When the world needs more tellurium, it needs more copper refineries to recover tellurium from the anode slime left over after electrolytic copper purification. When the world needs more indium, it needs more zinc smelters processing indium-bearing zinc ores and choosing to install the additional recovery circuits required to capture the indium rather than letting it wash into the waste stream. In both cases, the decision to produce more of the by-product is made by an operator whose business model is the primary metal — and whose investment decisions, expansion timelines, and operational priorities are governed by the economics of copper or zinc, not the economics of indium or tellurium. The by-product supply ceiling is the hardest constraint in the critical minerals supply chain to solve, because it doesn’t respond to any of the normal market signals. You can’t mine what doesn’t have a mine.

This matters now because the two fastest-growing applications for indium and tellurium are both critical to the energy transition — and both are scaling into a supply structure that physically cannot scale with them.

Indium: the element on every screen

Global indium production was approximately 900 metric tons in 2023, with China producing roughly 60%, South Korea 12%, and Japan 8%. Indium’s dominant application — over 50% of global demand — is indium tin oxide, a transparent conductive film deposited on glass or plastic substrates. ITO coats the touchscreen on every smartphone, every tablet, every laptop, every ATM, every airline check-in kiosk, every Tesla center console, and every flat-panel display manufactured in the last two decades. When you swipe your finger across a screen, you are interacting with a layer of indium tin oxide roughly 200 nanometers thick. The combination of electrical conductivity and optical transparency that ITO provides has no commercially viable substitute at the price and performance level the display industry requires.

The second major application is CIGS — copper indium gallium selenide — thin-film solar cells. CIGS panels are lighter, more flexible, and perform better in low-light and high-temperature conditions than conventional crystalline silicon panels, making them attractive for building-integrated photovoltaics, curved surfaces, and military applications. The CIGS market is small relative to silicon — less than 2% of global indium demand currently goes to solar — but the technology is one of three thin-film architectures (alongside CdTe and perovskites) competing for market share in applications where rigid silicon panels don’t fit. If CIGS deployment scales with the broader solar buildout, indium demand from that sector alone could double or triple within a decade.

The by-product constraint is the ceiling. Indium is recovered from the residues of zinc smelting — specifically from the zinc sulfide ores that happen to contain indium at concentrations of 1 to 100 parts per million. Not all zinc ores contain indium. Not all zinc smelters have installed recovery circuits. The decision to install a recovery circuit — which requires additional capital expenditure and process complexity — is made by a zinc smelter operator whose primary revenue comes from zinc. If zinc prices are low and indium prices are high, the smelter might invest in recovery. If zinc prices are high, the smelter has no incentive to complicate its operation for a by-product that contributes a small fraction of total revenue. The production ceiling for indium is set by the intersection of zinc ore geology, zinc smelter economics, and the discretionary decision of zinc operators to capture a by-product they are not required to capture. That’s not a supply chain. That’s a side hustle with a geological asterisk.

China’s 60% share of global indium refining creates the same concentration risk the Rare Earth Elements course has documented for gallium, graphite, antimony, and lithium refining. The gallium post already covered the mechanism: China’s 2023 export controls on gallium and germanium demonstrated that by-product metals refined primarily in China can be restricted through the same licensing regime Beijing has applied to every subsequent mineral. Indium has not been restricted. The infrastructure for restricting it is identical to the infrastructure that restricted gallium.

Tellurium: the element inside America’s solar bet

Tellurium’s story is simpler and stranger. Global production in 2023 was approximately 640 metric tons — roughly two-thirds the volume of indium and measured in quantities so small that industry analysts note the actual available supply may be “significantly higher” than official figures because copper refiners don’t always track or report tellurium recovery. Tellurium is extracted from the anode slime that accumulates during electrolytic copper refining — a residue that also contains selenium, gold, silver, and platinum group metals. Over 78% of tellurium extraction occurs in three countries: China, Japan, and Canada. The United States has two electrolytic copper refineries — one in Texas, one in Utah — that produce copper telluride from tellurium-bearing anode slimes. That’s it. Two facilities, producing a fraction of domestic demand.

Tellurium’s critical application is cadmium telluride solar cells — CdTe panels — manufactured almost exclusively by one company: First Solar, headquartered in Tempe, Arizona. First Solar is the largest solar manufacturer in the Western hemisphere and the only major solar company that does not use crystalline silicon. CdTe panels currently represent 21% of the U.S. solar market and 4% of the global market. First Solar’s domestic production capacity is set to reach 14 gigawatts by 2026, driven by the Inflation Reduction Act’s manufacturing incentives. The company is building or expanding factories in Ohio, Alabama, and Louisiana. The entire strategic bet — reshoring American solar manufacturing away from Chinese silicon supply chains — depends on a thin-film technology whose active ingredient is a by-product of copper refining produced at roughly 640 metric tons per year globally.

The Department of Energy’s perspective paper on CdTe photovoltaics states the constraint plainly: tellurium’s “constrained availability may place a practical limit on the maximum size of the CdTe PV supply chain.” The limit hasn’t been reached yet. But the industry roadmap targeting 100 gigawatts of CdTe manufacturing by 2030 requires tellurium supply to roughly triple from current levels, and the only way to triple tellurium supply is to either triple the number of copper refineries recovering tellurium from anode slime — an investment decision made by copper companies for copper reasons — or to dramatically improve the recovery rate at existing refineries, most of which were not designed to optimize tellurium extraction because tellurium was never what they were built to produce.

The copper shortage documented elsewhere in this cluster creates a compounding irony: the energy transition needs more copper for wiring, grid infrastructure, and EV motors. It also needs the tellurium that comes out of copper refining as a by-product. But copper mines are not copper refineries. New copper mines in Chile and Peru ship concentrate to smelters in China — and Chinese smelters are not obligated to supply tellurium to American CdTe solar manufacturers. The supply chain for America’s silicon-free solar bet runs through the same Chinese refining infrastructure that the policy was designed to avoid.

The by-product problem across the course

Indium and tellurium are not the only by-product metals in the Rare Earth Elements course with this structural constraint. Platinum group metals include iridium — produced at 7-8 tonnes per year exclusively as a by-product of platinum mining — whose potential scarcity could bottleneck the entire hydrogen electrolyzer industry. Germanium, covered in the gallium/germanium post, is a by-product of zinc smelting, just like indium, and faces the same structural ceiling. Cobalt is predominantly a by-product of copper and nickel mining — the conflict minerals post documented the DRC’s artisanal mining as the exception to by-product dependency, not the rule.

The pattern is consistent: by-product metals cannot be produced independently of their host metals. Their supply responds to the economics of copper, zinc, nickel, or platinum — not to the economics of indium, tellurium, germanium, cobalt, or iridium. When the energy transition creates demand for these by-products that outpaces the growth rate of their host metal industries, the result is a supply ceiling that no amount of investment in the by-product itself can raise. The ceiling can only be raised by expanding host-metal production — which requires mines that take 7-10 years to permit and build, serving a market (copper, zinc, nickel) whose economics may not justify the expansion at any given moment. The lithium supply chain at least has the theoretical advantage that lithium is the primary product: if you need more lithium, you build a lithium mine. If you need more tellurium, you build a copper refinery and hope the anode slime contains enough tellurium to matter.

Why they share a lecture

Indium and tellurium are paired in the Rare Earth Elements course because they are the clearest illustration of the by-product supply ceiling — the constraint that separates critical minerals whose production can theoretically respond to demand from critical minerals whose production cannot. The vanadium supply chain is concentrated but primary — if vanadium prices rise, someone can open a vanadium mine. The antimony supply chain is concentrated and primary. The semiconductor supply chain is concentrated but can, in theory, be duplicated through fab construction. Indium and tellurium cannot be duplicated. They can only be recovered from processes designed to produce something else, at rates determined by someone else’s business model, from geological deposits whose by-product content was never the reason the deposit was developed.

This is the kind of supply chain our Rare Earth Elements course was built to map — where the touchscreen industry runs on a layer of indium 200 nanometers thick recovered from zinc smelter residues, America’s silicon-free solar strategy depends on 640 metric tons of tellurium recovered from copper refinery anode slime, and neither supply chain can be expanded by investing in the thing you actually need more of.