Are Tektites Extra-Solar-System Meteorites?

Abstract

RECENT communications to Nature ¹ indicate that the origin of tektites is still a mystery. New evidence supporting an extra-terrestrial origin has been obtained by Ehmann and me² ; we have found radionuclides induced by cosmic rays (aluminium-26 and beryllium-10) in some tektites (australites and Libyan Desert silica-glass) at levels comparable to those observed in stone meteorites and considerably above any conceivable levels of production by cosmic or terrestrial radiations at or beneath the Earth's surface. This finding practically eliminates not only the Earth, but also the Moon, as the source of tektites, since the bulk of lunar material expelled in collisions of giant meteorites with the Moon¹ would undoubtedly originate at depths of at least several metres, where the cosmic radiation would be negligible in intensity. Although these findings require confirmation and more adequate controls, it will be assumed in the following that tektites are glass meteorites from outside the terrestrial system.