China’s customs tariff has a line for antimony trisulfide. America’s does not.

Antimony crosses borders under five customs codes, and none of them covers the compound defence buyers need most. China gives antimony trisulfide a line of its own. The United States files it under “other sulfides”, where it cannot be counted.

How the codes work, what each one carries, and why a figure for “antimony” rarely means what it appears to.

China can count the antimony trisulfide it exports. The United States cannot count what it imports.

China’s national customs tariff carries a dedicated line, 2830.90.20, for antimony sulfide, and the Ministry of Commerce listed that code among the antimony items placed under export licensing by Announcement 2024 No. 33. The United States tariff schedule has no equivalent. The only sulfides it names under the same subheading are zinc and cadmium; antimony trisulfide falls into 2830.90.90.00, “Other”. The United Kingdom sits between the two, listing antimony sulfides together with those of calcium and iron under 2830.90.11.

The gap matters because of what trisulfide does. It is the antimony compound in ammunition primers, bought against United States military specification MIL-A-159D, and qualifying a new source takes years: United States Antimony Corporation’s qualification award from the Defense Logistics Agency was reported in September 2019, and its third and final sample approval came in March 2023. Whatever primer-grade material enters the United States is recorded alongside every other unnamed sulfide.

It may not be recorded as a sulfide at all. In ruling HQ 967661, United States Customs and Border Protection held that stibnite, the natural trisulfide mineral, belongs under ore and concentrate rather than with the chemical sulfides so long as it has not been chemically modified. Depending on how it was made, the same compound can cross the border under two different headings.

The reason trisulfide slips through is structural. Every traded good is classified under the Harmonised System, the World Customs Organization’s six-digit nomenclature, which national tariffs then extend with further digits. Antimony itself moves under five six-digit subheadings. 2617.10 is ore and concentrate, overwhelmingly stibnite upgraded by flotation, and it is the code a mine exports on. 2825.80 is antimony oxides, which in practice means trioxide, the flame retardant synergist that takes most civilian consumption. 8110.10 is unwrought antimony, meaning metal in ingot or regulus, together with powders. 8110.20 is waste and scrap, and 8110.90 is the residual line for other articles of antimony.

Trisulfide is in none of them. As a manufactured chemical compound it belongs in chapter 28 under heading 2830, sulfides, where the World Customs Organization’s explanatory notes name antimony sulfides explicitly but the six-digit nomenclature gives them no subheading of their own. Whether a country can see the compound depends entirely on whether its national tariff adds the digits to separate it. China’s does. The United States’ does not.

The five antimony codes are not complete either. Most secondary antimony is recovered at secondary lead smelters as antimonial lead and goes back into lead-acid batteries, according to the United States Geological Survey. That metal trades as lead, outside every antimony code.

Each code also carries a different quantity of antimony per tonne, which makes adding them misleading. Antimony trioxide is Sb₂O₃. On standard atomic masses of 121.760 for antimony and 15.999 for oxygen, antimony is 83.54 per cent of it by weight, so a tonne of trioxide holds about 835 kilogrammes of antimony against close to a tonne in unwrought metal. Summing the codes on gross weight overstates contained antimony, and by a margin that shifts whenever the mix between oxide and metal changes. A time series built on that sum can rise or fall simply because the balance between oxide and metal has shifted, with no change in the antimony actually traded.

Most published figures also cover only some of the codes. Eurostat’s latest release on trade in critical raw materials restricts its antimony reporting to oxides and unwrought antimony in powder form, citing data confidentiality, so ore, scrap and other articles are left out. On that basis, EU antimony imports fell from 25,000 tonnes in 2019 to 21,000 tonnes in 2025, while exports rose from 8,100 tonnes to 12,900 tonnes.

Read as a single number, that looks like a market shrinking at one end and growing at the other. Read by product, it is the signature of a converter economy. The European Commission’s Joint Research Centre finds that the EU imports antimony metal both for its own industry and to make oxides, and that it is a net exporter of antimony oxides. Europe buys metal, turns it into trioxide, and sells part of the trioxide abroad.

Where that metal comes from has also shifted: Tajikistan supplied 52 per cent of EU antimony imports by value in 2025, followed by Vietnam with 12 per cent and Myanmar with 9 per cent, while China’s share fell from 16 per cent in 2024 to 3 per cent. The fall in China’s share overstates how far supply has moved beyond Chinese reach. Tibet Huayu Mining has owned half of TALCO Gold, which works the Konchoch gold-antimony deposits, since 2017, and in July 2026 the venture commissioned a plant able to make up to 5,000 tonnes of antimony metal a year. Not all Tajik output is Chinese-held: Anzob, which works the Dzhizhikrut deposit, has been wholly owned by the US-based Comsup Commodities since 2006 and sells into Europe. Customs data records the country a shipment leaves from, not who owns the mine behind it.

No customs code, including China’s line for trisulfide, separates civilian from defence demand, because a code describes a material, not a use. Trisulfide goes into brake pads as well as primers. Trade statistics carry no end-use field, and a tonne of trioxide bound for a cable sheath is recorded exactly like a tonne bound anywhere else. End use is tested elsewhere, in licensing. China’s Announcement 2024 No. 33 requires exporters of controlled antimony items to file end-user and end-use certificates, and Article 1 of Announcement 2024 No. 46 prohibits exports of dual-use items to United States military end-users. The licence file and the customs record answer different questions, and only one of them is published.

For a defence buyer, the practical lesson is narrow and uncomfortable. Chinese customs can see the primer compound move. United States trade data cannot, and a buyer reading it for reassurance about primer-grade supply will find the material folded into “other sulfides” or classed as ore. Beijing licenses what it can count. Washington is paying to rebuild a primer supply chain it cannot see in its own trade data, when its tariff schedule already gives zinc and cadmium sulfides lines of their own under the same heading. A line for antimony sulfide would not add a tonne of supply, but it would close the information gap. Until then, any figure that says only “antimony” is silent on the primer.