Cristobalite inclusions in libyan glass

Weight: 10.81 g
Size: 34.4 x 22.0 x 16.8 mm


Sample type: unpolished, natural irregular shape
Origin: Egypt

Libyan desert glass  – first discovered in 1932 in the Western Desert of Egypt, nearby the Libyan border, this material offers an enigma to scientists since then. Most geologists relate the origin of this glass to meteoritic impact produced 28.5 million years ago, that caused melting of impacted rocks, similar to moldavite and other tektites. There are many proofs to this theory, including presence of swirls and partly digested mineral phases, lechatelierite (melted quartz) and baddeleyite (high temperature breakdown product of zircon, typically found in tektites). Moreover, chemical studies show the existence of meteoritic component in the glass, revealed in higher concentrations of Co, Ni and Ir in dark bands that occur in some Lybian desert glass samples. Also, Re-Os isotopic data dark bands provides a proof of cosmic component in the Libyan desert glass.

Nevertheless, there are some scientists who still offer alternative non-impact theories for the formation of Libyan desert glass, for example, hydrovolcanic hypothesis.

Inclusions in Libyan desert glass are very characteristic, they are typically represented by groups of gas bubbles, swirls, and sometimes cristobalite “snowballs”. Micro-Raman spectroscopy also revealed the presence of titanium dioxide in two polymorphic species – rutile and anatase, and minerals unusual for high-temperature glasses such as anhydrite and aragonite.