A modern-day gold rush is sweeping across the Sahara. Thousands of young Africans are digging through the dunes with pickaxes – and risking their lives in search of precious treasure.

The Sahara, the largest desert on Earth, conceals vast deposits of fresh water beneath its sands. Just a few thousand years ago, it was a green land , inhabited by humans and animals.

A giant patch of black, fossilized lava that was spewed across the Sahara desert over millions of years looks like an eerie, gold-speckled shadow in this stunning composite of three years' worth ...