Coltan

What it is

“Coltan” is short for columbite-tantalite, a mineral from which two metals are obtained: niobium (once called columbium) and tantalum. They are separated and refined in plants, often far from the mines.

Tantalum (Ta)

Grey, hard metal that resists heat and corrosion.

Niobium (Nb)

Metal similar to tantalum, also called columbium; used mainly in steels.

Artisanal mine

Mine dug by hand or with simple tools by small groups of miners, with few controls.

3TG

Tin, tantalum, tungsten and gold: the “conflict minerals” of European and US rules.

What it is used for

• Tantalum: electronic capacitors, high-temperature alloys, carbides for tools and equipment that must resist corrosion. The United States has not mined it since 1959 and imports all of it.
• Niobium: in the United States about 77 % goes into steels and about 23 % into superalloys.
• Tantalum is also recovered from scrap: US imports include tantalum waste for recycling.
• It can be partly replaced, for example by aluminium, ceramics or niobium in capacitors, but often with lower performance or higher costs.

Sources: USGS, Mineral Commodity Summaries 2026: Tantalum; USGS, Mineral Commodity Summaries 2026: Niobium.

Coltan and the war in eastern Congo

In the east of the Democratic Republic of the Congo armed groups also finance themselves with minerals. The UN Group of Experts, which monitors the Congo sanctions for the Security Council, reports on this.

• Since 30 April 2024 the armed group AFC/M23 has controlled the town of Rubaya and its mining area, with the largest coltan mine in the Great Lakes region (December 2024 report, para. 56).
• According to the experts, M23 controlled the trade and transport of about 120 tonnes of coltan a month and earned at least 800,000 dollars a month from it, with a tax of 7 dollars per kilo (paras. 64–66).
• At least 150 tonnes of coltan were exported illegally to Rwanda and mixed with Rwandan production: for the experts, the largest contamination of mineral supply chains recorded in the region (summary and para. 57).
• In the final report of July 2025 the experts write that illegal mining in M23 areas, smuggling to Rwanda and sale as Rwandan minerals reached “unprecedented levels”; they also question the production Rwanda declares (summary and paras. 115–120).

The Government of Rwanda rejects the accusations; President Paul Kagame said the experts’ reports have nothing to do with the actual situation (Associated Press, July 2025).

At the end of June 2025 Congo and Rwanda signed a US-brokered peace agreement. According to the USGS, if it holds it should make eastern Congo and the region’s mineral trade more stable.

Sources: United Nations, Group of Experts on the DR Congo, midterm report (S/2024/969, December 2024); United Nations, Group of Experts on the DR Congo, final report (S/2025/446, July 2025); Associated Press, “UN experts say Rwanda supported rebels in Congo and smuggled minerals at ‘unprecedented levels’”, July 2025; USGS, Mineral Commodity Summaries 2026: Tantalum.

Children, labour and the environment

• The US Department of Labor reports that in eastern Congo children mine and carry coltan, cassiterite (tin), wolframite (tungsten), diamonds and gold, and counts forced labour in these mines among the worst forms of child labour (2022 report).
• The UN experts report forced labour imposed by M23 to widen the roads used by mineral trucks (December 2024, para. 63).
• Mines also threaten protected areas: Kahuzi-Biega National Park, in South Kivu, is on the List of World Heritage in Danger, and UNESCO follows the closure of mining sites inside it.

Sources: U.S. Department of Labor, Findings on the Worst Forms of Child Labor: Congo (DR), 2022; United Nations, Group of Experts on the DR Congo, midterm report (S/2024/969, December 2024); UNESCO, Kahuzi-Biega National Park, state of conservation 2023.

Rules and traceability

• European Union: since 1 January 2021 importers of tin, tantalum, tungsten and gold (as ores or metals) must check their supply chain following the five steps of the OECD guidance. The rule directly concerns 600 to 1,000 importers (Regulation 2017/821).
• United States: since 2012 listed companies must tell the SEC whether they use these four minerals from Congo or neighbouring countries (Dodd-Frank Act, section 1502).
• OECD: the guidance for responsible supply chains of minerals from conflict-affected and high-risk areas (third edition, 2016) describes the checks companies should carry out.
• Traceability: the mineral is tagged at the mine (ITSCI system). UN reports show its limits: in May 2024 tagging in the Masisi area was suspended, and in 2025 the tags of looted minerals, later sold as Rwandan, were cancelled.

Sources: European Commission, Conflict Minerals Regulation; SEC, conflict minerals disclosure rule (2012); OECD, Due Diligence Guidance for Responsible Supply Chains of Minerals (third edition); United Nations, Group of Experts on the DR Congo, midterm report (S/2024/969, December 2024); United Nations, Group of Experts on the DR Congo, final report (S/2025/446, July 2025).