In the back yard of the federal police headquarters in Roraima, the northernmost state of Brazil, giant sacks lie strewn and overflowing with a jet-black, gravel-like mineral: cassiterite. Although less high-profile than other items seized during a crackdown on illegal mining in this Amazon state – including a Sikorsky S-76 helicopter painted in the colours of the Brazilian flag – cassiterite has become so sought-after that it is nicknamed “black gold”.
Cassiterite is the chief ore of tin, a less heralded but critical mineral for the energy transition. It is used in coatings for solar panels, lithium-ion batteries and solder for electronics, including wind turbines, mobile phones, computers and industrial alloys.
According to the International Energy Agency, the demand for critical energy minerals is due to almost triple by 2030 to meet energy-transition needs.
In a world market heated by demand from multinational companies and with prices for tin on the rise – up 29% in the first six months of this year – Brazil has become one of the world’s largest exporters of the metal.
However, as well as increasing profits and commodity exports, the rush for cassiterite has become a new environmental and policing problem.
Considered a conflict mineral in the European Union and the US, cassiterite has increasingly attracted not only companies but illegal mining gangs in the Brazilian Amazon.
Criminals have also profited from the illegal extraction of manganese and copper, which are also vital to the energy transition. Prices for these minerals have rocketed this year, with manganese nearly doubling.
The search for critical metals gained momentum after Brazil’s government launched initiatives to encourage critical mining investment, given the growing interest of international mining firms in the country’s mineral wealth.
The development bank BNDES and the Brazilian mining multinational Vale are planning to launch an investment fund to support domestic projects to produce critical minerals – including tin, manganese and copper – with the government publishing an investors’ manual.
At the same time, the activity of illegal mining groups has threatened the Indigenous Yanomami people. Gangs already active in gold mining, including in the largest Indigenous territory, have seen cassiterite, manganese and copper as valuable by-products.
At $14-$21 (£11-£16) a kilo, cassiterite is small change compared with gold, which has climbed to record highs of nearly $80,000 a kilo this year. However, it is more plentiful and easier to extract.
Federal agents say that a goldmining operation on Yanomami land could yield about 4kg of gold a month on average, while producing 300kg of cassiterite a day. But mining for gold, especially on isolated tracts of Yanomami land, requires significant cash to pay for food and other costs for the thousands of miners and fuel to keep diesel-guzzling machinery running.
“Cassiterite on the Yanomami land basically finances the gold mining,” says Diego Milléo Bueno, the superintendent in Roraima for Brazil’s environmental agency Ibama.
“Cassiterite is the base; it pays for the fuel, it pays for the workers; it pays for everything.”
So far this year, authorities have seized and destroyed more than 38 tonnes of cassiterite on Yanomami territory, according to government data.
Davi Kopenawa, a celebrated Yanomami activist and shaman, says: “Lots of people from abroad are looking at the richness of Brazil and its Indigenous lands like never before.”
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Federal highway police in Roraima first started pulling over trucks loaded with cassiterite in April 2021, during the Covid-19 pandemic. “We didn’t know what it was; we had to get it tested,” says one officer, Isaías Magalhães, whose team seized 63 tonnes that year.
“Then, we noticed they began transporting it hidden under other products such as fish and watermelon.”
Cassiterite is taken from the far-flung Yanomami territory via planes or boats, most commonly in clusters of 50kg sacks. Helicopters and quad bikes are often used to transport it locally, and the metal is then taken to farms across the border of the Yanomami land.
From Roraima, drivers transport cassiterite in trucks to neighbouring Amazonas state. From Manaus port – where 60 tonnes of cassiterite destined for China were seized in one swoop in 2022 – it can access the rest of Brazil or the world.
In 2022, the last year of the far-right government of Jair Bolsonaro, as tin prices hit an all-time high, the highway police seized 191 tonnes of cassiterite. The following year, the left-leaning Luiz Inácio Lula da Silva took power and promised to end illegal mining on Indigenous lands; roadside seizures plummeted to 25 tonnes.
Amid corruption problems among public officials, seizures have decreased in the last two years. In June, the authorities seized 23,000 tonnes of manganese due to be exported to China, while in July, federal police closed an illegal manganese mining site on the land of the Kayapó Indigenous people in Pará state.
At the beginning of the year, also in Pará, police raided several sites prospecting for copper and gold, one of which included workers held in slave-like conditions.
Last year, one federal police operation, Gold Disk, discovered a mammoth cassiterite-laundering scam involving a popular Brazilian singer agent and another with the illegally extracted mineral sold to a firm that has several multinationals as listed clients.
The federal police chief in Roraima, Caio Luchini, says it is easier to conceal the illegal origins of cassiterite and similar minerals than of gold, which has “more rigid controls”.
“With this boom of cassiterite and other minerals, it is worth re-analysing our legislation,” he says.
Last December, federal police investigated White Solder, a leading Brazilian tin producer, for buying cassiterite from a mining cooperative that illegally sourced it from the Yanomami territory. White Solder was also listed as a supplier to household names including Amazon, Disney and Starbucks, as revealed by the Brazilian newspaper Folha de S Paulo.
The Guardian contacted White Solder and Disney but has not received any response.
Amazon says it is “committed to providing products and services that are produced or supplied in a way that respects human rights and the environment” and expects its suppliers to support its efforts “to identify the origin of gold, tin, tungsten and tantalum used in products that we manufacture or contract.”
Starbucks said it was “committed to ethical sourcing in our supply chain and we do not have contracts in place with White Solder”.
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In Roraima’s capital, Boa Vista, mining has so much public support that a statue of a miner stands outside its legislative assembly and Bolsonaro received an overwhelming vote in the state in the 2022 presidential elections.
Many in Roraima blame the crackdown on mining as a reason for unemployment and hardship. “The city is weak,” says Rafael, 32, who has been a miner since he was 17 and spoke on condition of not giving his surname.
“Before, people would arrive from the garimpo with money to spend,” he says, using the Brazilian Portuguese term for a small-scale, illegal mining camp.
He says that in three months, he could earn up to 40,000 reais (£5,500), paid in gold, compared with Brazil’s minimum monthly wage of R$1,412. “I spent it all,” he chuckles.
Rafael says he paid R$3,000 for a flight out of the Yanomami territory last year just before the crackdowns started, and since then, he has been working in mining pits in Guyana, where many other Brazilian miners have also gone. “It’s safer,” he says. “In Brazil, you have to sleep with one eye open.”
Although he is now recovering from his eighth bout of malaria, Rafael plans to return to Guyana – where the mining “is legal” – as soon as he is better, even though he earns less money there.
Another Brazilian working in Guyana is Rodrigo de Mello Martins, also known as Rodrigo Cataratas, who is being investigated for illegal mining.
Cataratas ran as a federal lawmaker for Bolsonaro’s Liberal party in the 2022 elections, declaring R$33m in assets, including several aircraft. In a written statement to the Guardian via his lawyer, Cataratas said he was collaborating with authorities and “trusts that the truth will prevail” and “mining, when carried out responsibly, can be a driving force for economic development, generating jobs and improving local infrastructure.”
While experts acknowledge the drop in illegal mining since the crackdowns, some fear that an increase in drug seizures in Roraima is a sign that organised crime groups are using illegal mining logistics routes in Yanomami territory for drug trafficking.
Recent initiatives, such as the United Nation’s Panel on Critical Energy Transition Minerals, launched by the UN secretary general, António Guterres, have stressed the importance of respectful engagement with Indigenous and other local communities.
“There’s a lot of harm happening in extraction that’s legal,” says Aimee Boulanger, the executive director of the Initiative for Responsible Mining Assurance, a non-state member of the UN panel.
“We have the technology to follow best practices in mining already and we have some companies stepping up to the opportunity moment,” says Boulanger. “But we need laws to require it and markets to value it.”
The report was carried out with the support of the Earth Journalism Network
