ROODEPOORT, South Africa – Julius Mthembu's mud-spattered face lit up as he held a tin pan and pointed to the glimmering flecks of hope lying among sand and water: gold. The find meant the 48-year-old would eat that week.

"It's difficult. I don't make a lot of money here," Mthembu said as beads of sweat stood out on his forehead. The Mozambican and his countryman Santos Viriato have been gathering dirt from the shuttered Durban Deep mine and sifting it for leftover gold for two months.

South Africa, once the world's foremost gold producer, has been experiencing a labor upheaval in its critical mining sector, and Mthembu and Viriato are emblematic of both the troubles and the hope that persists, with not only gold but also platinum, chrome and other minerals remaining untapped.