Located close to the Libyan edge of the Great Sand Sea is an area which contains one of the great mysteries of the region. Natural green silica glass can be found lying between the dunes. Pieces vary in colour, clarity and size. Rediscovered in the 1840s, this glass was known to the ancient Egyptians. In 1998, a member of an Italian team investigating the origins of the glass was permitted to examine Tutankhamun's jewellery. The green scarab dominating the boy king's pectoral was found to be made from a piece of Libyan Desert Silica Glass. Though proving the glass was known about –and valued- in antiquity, this does not shed any light on the origins of the glass. Extreme heat would be needed to form this glass giving rise to many theories from volcanic activity to an extra-terrestrial body crashing into the earth. There is a suspected meteorite crater 150km away from the glass field. However, there is no glass at the actual crater site so the source of the glass remains a mystery to this day.