The man was digging a toilet in his back yard when his shovel struck a shimmering blue vein of cobalt.
At least that's the legend in Kolwezi. Once a few locals discovered the metal underfoot five years ago, everyone grabbed shovels and pickaxes; they tunnelled beneath homes, schools and churches. And that's how a working-class suburb, on the edge of a densely populated city of half a million, became a hive of pits and tunnels.
"My neighbours started to dig in 2013 and I followed their lead," said Edmond Kalenga, who went as deep as 20m under his home. "The minerals are like a snake moving through the village. You just followed the snake."
All told, he made $12000 (about R140000) selling the metal to local middlemen - a fortune in the Democratic Republic of Congo, where most people live on less than $1.90 a day. He built a five-room house in a new part of town.
Others weren't so lucky. Dozens were dying in the mines each week until officials banned the digging in April last year, according to local government estimates.
The Congo is by far the world's biggest supplier of cobalt, the key ingredient in the rechargeable batteries needed to power everything from Apple gadgets to Tesla cars. For many in Lualaba province, where the richest deposits are found, digging for cobalt by hand isn't a choice: it's the surest way to earn a living.
Their entrepreneurial efforts, also called artisanal mining, accounted for about 15% of Congo's cobalt output in 2017, according to Darton Commodities. That's roughly $1-billion at spot prices and it's sure to grow as global demand surges. Even now, mining officials in the Congo say the true figure is much higher.
The artisanal production puts corporate behemoths in a public relations bind. The pits can be dangerous and in 2016, Amnesty International found children involved in sorting, washing, crushing and carrying cobalt.
Since then, major buyers have sought to avoid the informal mines, opting for international companies that run industrial operations, such as Glencore. Some, like Apple, have begun work on verifying standards at artisanal mines and improving conditions. But progress has been slow...