The quarries are the main employers in Minya province, some 300 kilometers (180 miles) south of Cairo. Around 45,000 people, including children, work in an estimated 1,500 quarries, digging out stones that later will be used in construction or powdered to be used by pharmaceutical and ceramic companies.

But the work, paying $7 to $13 a day, is backbreaking — and dangerous. Workers have suffered amputations and electrocutions, sometimes dying.

One laborer, 15-year-old Baskharoon Mounir, lost his left arm to a cutting machine in 2013 after working for only a month without safety equipment or training.

"I wish I could go back, even with one arm." Baskharoon says. "It would be better than staying at home, but when they see me, they do not allow me to work."

Quarry workers — many children younger than Baskharoon — are overwhelmingly day laborers. In the village of Shurafa, most wait each day on a bridge to be picked up for work by managers driving by in pickup trucks.

Deaths and injuries largely go undocumented, says Hossam Wasfy, the executive director of Wadi El Nil, a charity that focuses on child labor. In one village called Nazlet Abeed, there were 18 quarry deaths alone in 2009, he says.

After Egypt's 2011 uprising, quarry workers formed their first independent workers' union with the help of the charity, Wasfy says.

"The uprising had a mixed effect on the workers," he says. "Work opportunities may have reduced due to the economic situation, but laborers are now organizing and becoming aware of their rights."

All Photos by Associated Press photographer Mosa'ab Elshamy.