Minerals under Extreme Conditions: New Data from Silicate and Phosphate Inclusions within Libyan Desert Glass (Western Egypt) and Implications for Its Origin

Libyan Desert Glass is an enigmatic material found near the Egypt-Libya border, in the corridors between dunes of the Great Sand Sea. Although it has been studied for almost one hundred years, its origin is still debated. The most probable cases are due to impact cratering or aerial bursting. During this work seven cristobalite inclusions, three zircon inclusions and two phosphate inclusions (xenotime-(Y) and monazite-(Ce)) have been studied via polarised light optical microscopy, micro-Raman spectroscopy, scanning electron microscopy, electron probe micro-analyser, electron backscatter diffraction, transmission electron microscopy and three-dimensional electron diffraction. The aim was to understand how such inclusions formed within the glass and if they can exhibit a high-pressure signature, in order to gain better knowledge regarding the origin of Libyan Desert Glass.