Libyan Desert Glass with a dark streak and Cristobalite inclusions Cushion cut ,faceted - Size : 20 x 20 x 15 mm - Weight : 32.2 carat Dark streaks and different types of inclusions in Libyan Desert Glass (LDG) collected from the LDG strewn field in Egypt were investigated. Rare transparent spherules enclosed in the glassy matrix are characterized by concentric cracks, irregular internal cracks, intense twinning, and considerable amounts of Ti and Al. Raman spectra show that the spherules are ?-cristobalite. Their occurrence together with lechatelierite indicates quick heating of the source rock to at least 1550 °C, followed by rapid quenching leading to crystallization of ?-cristobalite, which upon cooling inverted into ?-cristobalite. Several specimens of Libyan desert glass (LDG), an enigmatic natural glass from Egypt, were subjected to investigation by micro-Raman spectroscopy. The spectra of inclusions inside the LDG samples were successfully measured through the layers of glass and the mineral species were identified on this basis. The presence of cristobalite as typical for high-temperature melt products was confirmed, together with co-existing quartz. TiO(2) was determined in two polymorphic species rutile and anatase. Micro-Raman spectroscopy proved also the presence of minerals unusual for high-temperature glasses such as anhydrite and aragonite. The origin of the glass is a controversial issue for the scientific community, with many evolving theories. Meteoritic origins for the glass were long suspected, and recent research linked the glass to impact features, such as zircon-breakdown, vaporized quartz and meteoritic metals. Some geologists associate the glass not with impact melt ejecta, but with radiative melting from meteoric large aerial bursts. If that were the case, the glass would be analogous to trinitite, which is created from sandexposed to the thermal radiation of a nuclear explosion. The Libyan desert glass has been dated as having formed about 26 million years ago. It was knapped and used to make tools during the Pleistocene.