The Great Sand Sea is the Egyptian desert area associated with Libyan desert glass, a yellow-green natural glass created by extreme heat.
Pieces of this glass are scattered across parts of the Sahara near the Egypt–Libya border. Most scientists link its formation to an intense airburst or impact event about 29 million years ago, although the exact mechanism remains debated. The heat melted surface material and produced glass that later weathered into fragments.
Libyan desert glass became especially famous after a yellow-green stone was found in a pendant from the tomb of the Egyptian pharaoh Tutankhamun. The material is sometimes called Libyan gold tektite, though its precise classification and origin have been discussed by researchers.
The Great Sand Sea is a huge field of dunes in the Western Desert. It should not be confused with the entire Libyan Desert, a broader geographic region extending across Egypt and Libya.