For decades, ideas about how the glass formed included melting during meteorite impact, or melting caused by an airburst from an asteroid high in Earth's atmosphere. In May 2019, Libyan desert glass samples were examined by Aaron Cavosie of Curtin University[12] via the
electron backscatter diffraction aka EBSD technique, and the results were published in the Journal of Geology : the glass is nearly pure silica which requires temperatures above 1,600 °C to form – hotter than any igneous rock on Earth. However, few mineral relics survived from whatever caused the melting, including a form of quartz called
cristobalite (a rarely occurring high-temperature mineral) and grains of the mineral
zircon derived from
reidite, although most have reacted to form a higher-temperature mineral called
zirconia when the melt reached over 1,700°C. The presence of still remaining zircon grains transformed from reidite (circa 10%), their orientation and shape revealed to be typical only of a meteoritic impact. Moreover, airbursts never yield this exact type of mineral transformation according to geological records.[10][13]
^Kramers, J.D et al (2013): Unique chemistry of a diamond-bearing pebble from the Libyan Desert Glass strewnfield, SW Egypt: Evidence for a shocked comet fragment. Earth and Planetary Science Letters 382, 21-31
doi:
10.1016/j.epsl.2013.09.003
^B. Kleinmann (1968): The breakdown of zircon observed in the Libyan desert glass as evidence of its impact origin. Earth and Planetary Science Letters 5, 497-501.
doi:
10.1016/S0012-821X(68)80085-8
^Weeks, R. (1984): Libyan Desert glass: A review. Journal of Non-Crystalline Solids, 67, 593-619.
doi:
10.1016/0022-3093(84)90177-7
^Seebaugh, W. R. & Strauss, A. M. (1984): Libyan Desert Glass: Remnants of an Impact Melt Sheet. LUNAR AND PLANETARY SCIENCE XV, 744-745. [Abstract.]
Bibcode:
1984LPI....15..744S
^Barbara Kleinmann, Peter Horn and Falko Langenhorst (2001): Evidence for shock metamorphism in sandstones from the Libyan Desert Glass strewn field. Meteoritics & Planetary Science 36, 1277-1282
doi:
10.1111/j.1945-5100.2001.tb01960.x
^Giovanni Pratesi, Cecilia Viti, Curzio Cipriani and Marcello Mellini (2002): Silicate-silicate liquid immiscibility and graphite ribbons in Libyan desert glass. Geochimica et Cosmochimica Acta 66, 903-911.
doi:
10.1016/S0016-7037(01)00820-1
^Greshake, Ansgar; Koeberl, Christian; Fritz, Jörg; Reimold, W. Uwe (2010). "Brownish inclusions and dark streaks in Libyan Desert Glass: Evidence for high-temperature melting of the target rock". Meteoritics & Planetary Science. 45 (6): 973–989.
doi:
10.1111/j.1945-5100.2010.01283.x.
S2CID128920720.
^
abCavosie, Aaron J.; Koeberl, Christian (1 July 2019). "Overestimation of threat from 100 Mt–class airbursts? High-pressure evidence from zircon in Libyan Desert Glass". Geology. 47 (7): 609–612.
Bibcode:
2019Geo....47..609C.
doi:
10.1130/G45974.1.
S2CID155125330.