زجاج الصحراء الليبية (بحر الرمال الأعظم)

Deep in the Western Desert, straddling Egypt and Libya, the Great Sand Sea is one of the planet's largest dune fields, an ocean of towering, wind-sculpted sand. Scattered across a remote corner of it lies something extraordinary: pieces of natural silica glass, pale yellow-green and glassy, formed by a fierce ancient heat event tens of millions of years ago.

The glass has a royal connection: a carved scarab of exactly this material sits at the centre of one of Tutankhamun's pectorals, meaning the ancient Egyptians prized it long before science could explain it. Reaching the glass fields requires a serious multi-day desert expedition, but even the dunes themselves, rolling to the horizon in perfect silence, are among Egypt's great wilderness experiences.