Origin of Libyan Desert Silica-Glass

Abstract

SINCE first reading of Libyan Desert glass¹, I have been intrigued concerning its origin. In the course of investigation of impurities in the glassy state, the role of trace germanium in fused silica was studied^2,3. All fused silica produced artificially from natural quartz contains trace germanium impurity. Two different fused silicas investigated contained 0.9 p.p.m. of germanium³. It occurred to me that the trace germanium content of Libyan Desert glass might offer a clue to its origin, as no trace germanium would be expected to volatilize selectively (as germanium(II) oxide) during sudden melting and quenching of a high silica-content glass.