Libyan Desert Glass

Libyan Desert Glass is a pale yellow to yellow-green natural glass of almost pure silica (about 98% SiO₂), found in the Great Sand Sea of western Egypt near the Libyan border. It formed about 28.5–29 million years ago from melted quartz-rich sand; recent studies point to a meteorite impact, though an airburst origin has also been argued and no source crater has been identified. It is an impact glass, often grouped with tektites, and is not a mineral or a meteorite.