Antimony’s uses in flame retardants, semiconductors, and defence.
Context and background
Antimony spent most of the last century as an obscure industrial input, familiar mainly to materials scientists and defence procurement officers. In August 2024, China imposed export controls on antimony products, and the metal’s profile changed almost overnight. Prices that had sat around US$5,500 ($7,838) per tonne in 2019 surged past US$50,000 per tonne by mid-2025. The metal became the subject of national security discussions, corporate procurement reviews, and a quiet scramble to identify alternative sources of supply outside China.
For investors following the critical minerals space, understanding what antimony actually is, what it’s used for, and why supply is so constrained helps explain why this particular market move wasn’t just a short-term price spike.
What is antimony?
Antimony is a chemical element, symbol Sb (from the Latin stibium), atomic number 51. In its pure form it’s a silvery-grey, brittle metalloid, sitting somewhere between a metal and a non-metal in its properties. It doesn’t occur widely in nature in its pure state — the primary ore mineral is stibnite (Sb₂S₃), a metallic sulphide with a distinctive needle-like crystal structure.
Antimony has been known and used since antiquity. Egyptians used the powdered mineral in kohl eyeliners. Early alchemists prescribed it as medicine, which, given its toxicity, was not a good idea. Today its value is industrial and strategic rather than cosmetic or medicinal, and the applications that matter most are ones most people never think about.
Flame retardants
The single largest end use for antimony globally is flame retardants, specifically as antimony trioxide (ATO). ATO doesn’t extinguish fires by itself — it works synergistically with halogenated flame-retardant compounds to interrupt the combustion process at a chemical level, significantly slowing the spread of flame through materials. The combination is used in plastics, textiles, circuit boards, insulation, rubber, and coatings across industries ranging from construction to aerospace.
The ubiquity of this application is easy to underestimate. Flame retardant requirements are embedded in building codes, vehicle safety standards, aviation regulations, and electronics manufacturing specifications across most developed countries. The plastic housing of a laptop, the insulation around electrical wiring, the seat foam in a commercial aircraft, the casing of a children’s toy — these and thousands of other products contain antimony trioxide as a direct consequence of fire safety rules. Without ATO, manufacturers would need to either reformulate around less effective alternatives or accept products that don’t meet regulatory requirements.
Semiconductors and electronics
Antimony’s role in semiconductors is less visible than its use in flame retardants but is becoming increasingly important. Indium antimonide and gallium antimonide are compound semiconductors used in infrared detectors, thermal imaging systems, and high-speed electronics. These materials operate at wavelengths that silicon-based semiconductors cannot reach, which makes them essential for specific applications rather than general substitutes for conventional chip materials.
Antimony is also used in lead-acid batteries, where it hardens the lead plates and improves charge-discharge performance; in solders and bearing alloys; and as a fining agent in glass manufacturing, where it helps eliminate bubbles in optical glass. None of these is as large as the flame-retardant market, but collectively they add up to a diverse base of industrial demand that is difficult to replace quickly.
An emerging application worth noting is antimony’s use in sodium-ion batteries, where antimony-based anodes are showing promise as an alternative to lithium-ion chemistry for certain grid-scale energy storage applications. This is still at a relatively early stage commercially, but it represents a potential new demand driver on top of existing industrial uses.
Defence
Antimony’s defence applications are where the geopolitical sensitivity becomes most acute. Since World War II, antimony has been used in armour-piercing ammunition, where it hardens lead alloys to improve penetration. It’s also a key material in tracer bullets, primer compounds, and night-vision equipment — indium antimonide is the semiconductor of choice for the infrared detectors used in night-vision goggles and thermal weapon sights. Precision optics, infrared sensors, and certain components in missile guidance systems also rely on antimony-based materials.
The United States consumed roughly 20,000–25,000 tonnes of antimony per year at the time China imposed export controls, with China accounting for around 63% of US imports. Ongoing conflicts in Ukraine and the Middle East had already placed pressure on ammunition supply chains before the export controls arrived, adding urgency to a situation that was already drawing attention in defence procurement circles.
Where antimony comes from
China, Russia, and Tajikistan together account for more than 90% of global antimony mine production. China alone accounted for approximately 48%. This degree of supply concentration in a single dominant producer is unusual even by the standards of critical minerals, where geographic concentration is common.
The situation is further complicated by the structure of China’s own supply chain. China’s domestic antimony production has declined by roughly 30% since 2018, and the country now imports more than 65% of its antimony ore concentrate, much of it from Tajikistan, before processing and re-exporting refined product. The chokepoint, in other words, is not just mining but refining — global refining capacity outside China exists but sits largely underused due to insufficient ore supply to feed it.
Antimony is not traded on any formal metals exchange. Prices are privately negotiated between buyers and sellers, often through long-term confidential contracts, which makes the market less transparent than copper, gold, or most other commodities. That opacity contributed to how quickly the market was caught off guard when Chinese export restrictions took effect.
What China’s export controls actually did
China announced export controls on antimony on 14 August 2024, with requirements for dual-use export licences for antimony and its products taking effect from 15 September 2024. In December 2024, China escalated the measures, issuing a directive prohibiting, in principle, exports of antimony to the United States.
The effect on the market was immediate. Chinese antimony exports fell by roughly 97% after the August 2024 restrictions, while global prices surged by approximately 200%. By mid-2025, prices had reached US$57,000–60,000 per tonne, compared to US$5,500 per tonne in 2019.
The situation shifted again in late 2025. Following a meeting between Chinese President Xi Jinping and US President Donald Trump in October 2025, China suspended export restrictions on antimony, gallium, germanium, and other critical minerals to the United States for one year, pending further bilateral negotiation. However, the underlying legal framework remained intact, and China subsequently published a whitelist for 2026 and 2027 designating only 11 companies authorised to export antimony globally. The controls can be reinstated, and the whitelist system means China retains structural leverage over supply regardless of the current truce.
Australia’s position
Australia holds the world’s fourth-largest antimony reserves, with significant stibnite deposits across Victoria, New South Wales, Queensland, and Western Australia. Currently, the Costerfield mine in Victoria is the only operation in Australia producing antimony, supplying 1,282 tonnes in 2024.
Several projects are at various stages of development. Larvotto Resources‘ (ASX:LRV) Hillgrove Project in New South Wales is Australia’s largest antimony deposit and one of the 10 largest in the world, with first ore production targeted for 2026 and projected output of around 5,400 tonnes of antimony per year. Southern Cross Gold’s (ASX:SX2) Sunday Creek Project in Victoria is targeting a maiden resource in 2027. A cluster of earlier-stage explorers are advancing projects in Victoria’s goldfields and elsewhere, drawn by the combination of high antimony prices and Australia’s standing as a stable, allied-nation jurisdiction at a moment when Western governments are actively seeking to reduce dependence on Chinese supply.
Australia is already a named partner in US discussions around critical mineral supply chain diversification. The Center for Strategic and International Studies has specifically identified increasing investment in Australia as a pathway to alleviating US antimony supply chain challenges.
Why it’s now on critical mineral lists
Antimony appears on the critical mineral lists of Australia, the United States, the European Union, the United Kingdom, Japan, and Canada. The common thread across all of these designations is the combination of strategic importance in defence and advanced manufacturing, high supply concentration in geopolitically sensitive jurisdictions, and the absence of readily available substitutes for its primary applications.
A material ends up on a critical minerals list when its potential disruption would cause harm that couldn’t be quickly remedied by switching to something else. Antimony meets that test clearly. Flame retardant formulations are embedded in regulatory standards that take years to change. Defence supply chains can’t be reformulated quickly. And the processing infrastructure needed to convert stibnite ore into antimony trioxide or refined metal is heavily concentrated in China and cannot be replicated in a matter of months.
Conclusion
Antimony moved from an obscure industrial input to a subject of national security policy in the space of roughly 18 months. The underlying reasons — extreme supply concentration, defence-critical applications, no obvious substitutes, and a dominant producer willing to use export controls as geopolitical leverage — were structural vulnerabilities that existed long before the August 2024 restrictions. They’re also vulnerabilities that are slow to fix, which is why the investment interest in antimony projects in Australia and other stable jurisdictions is likely to persist well beyond the current period of elevated prices and trade tension.
Write to Tyler Jefferson at Mining.com.au
Images: Mining.com.au, Wikimedia Commons & rawpixel
