In the lush hills of eastern DR Congo, where the trade in rare minerals has long fed unrest, miners complain that recent US rules against "conflict minerals" have bitten into their meagre income.
"Since they brought in this law, things did get worse," said miner Ombeni Chikala in South Kivu, the troubled mineral-rich eastern province of Democratic Republic of Congo.
Introduced in 2010, section 1502 of Washington's Dodd-Frank law -- known to the self-employed miners as "Obama's law" -- requires companies listed on the US stock exchange to report any use of conflict minerals to regulators.
However the US government this year said the law was under review.
Situated to the west of Lake Kivu, the green hills surrounding the small mining town of Numbi in South Kivu are dotted with mining sites -- some just holes in the ground, others large hills reduced to quarries.
Chikala, 32, digs for cassiterite and coltan near Numbi in sites validated as free of conflict minerals by the United Nations and USAID.
Cassiterite (used for tin) and coltan (for tantalum), along with gold ore and wolframite (for tungsten), are the four most common "conflict minerals" extracted by tens of thousands of Congolese miners.
Trade in the minerals, which power the world's consumer electronics, have helped fund and trigger foreign and local wars in eastern Democratic Republic of Congo in which millions of people have been killed and displaced in the last decades.
- 'Tagging is killing us' -
"In the past you could dig 100 kilos (220 pounds), you could take it wherever you want and sell it to anyone you want," said Chikala.
But under the new rules, the miners must comply with a traceability scheme set up by British organisation ITRI Ltd under which minerals are sold down the consumer chain via a system of "bag-and-tagging".
"This tagging system really is killing us," said Chikala's co-worker Byamungu Kabyona, 42.
"In the past we used to work freely, you can dig your stones," Kabyona said.
"You get your stones or you buy your stones, you can sell them to anyone you want, you can take them wherever you want as long as you have the card from the mining ministry and other documents from the government," he added.
Others argue however that the new system helps the small-scale miners.
A repeal of the US regulation would be "a tragedy for the artisanal mining sector," said Fidel Bafilemba, founder and director of the Support Group for Traceability and Transparency in the Management of Natural Resources, known by its French acronym GATT-RN.
"The region has been known for violent artisanal exploitation and if we have made any improvements, it's solely due to the pressure of this US law," he said.
- 'Completely chaotic' -
But local miners are not the only critics.
The immediate consequences of Dodd-Frank were "completely chaotic", said John Kanyoni, managing director of mining company Metachem Sarl and vice president of the Chamber of Mines.
He said economic activity had slumped, with loans lost and "thousands and thousands" of diggers out of work.
In 2014, Kanyoni helped draft a letter signed by 70 industry representatives, researchers, journalists and members of civil society criticising section 1502 and calling for a "more nuanced and holistic approach" with greater local consultation.
Though he acknowledged that the bill had been a "kind of catalyst" for positive change, he stressed that it was often the diggers who had to bear the costs of traceability and transparency.
- 'Not fair' -
"In the end, the diggers (are) the ones who will be losing more," said Kanyoni. "If you're getting two dollars more, three dollars more, this money will be going to the traceability, due diligence and certification schemes.".
Bafilemba, of GATT-RN, agreed, saying self-employed miners earn less for the minerals they sell because of ITRI fees imposed on exporters.
"This money is ... charged back to the miners. So in principle, it’s the miners who are paying this money. It’s not fair. It should be on the end-users, the giant electronic companies to pay this amount," Bafilemba said.
But while digging near Numbi, 33-year-old Salomon Kahizi said that though the prices had dropped, the area was safer nowadays for these lone miners, who had frequently been victims of robbery in the past.
"When you'd be digging or working they might show up and take everything... But nowadays, those kinds of attacks, we don’t see them anymore," Kahizi said.