Tektites are an unusual formation. The name comes from the Greek "tektos" meaning melted. Tektites have long been a mystery, and many theories were brought forward to explain what they are. Tektites were thought to be sand vitrified by lighting, or tears shed by comets, or even pieces of the moon torn off by large meteorites that were then hurled to the Earth. They are sometimes called "glassy meteorites" and this is perhaps the closest to what most scientists now believe they are.
In 1960 a careful study of tektites was undertaken. The lunar origin theory was abandoned after man walked on the moon. Today, most scientists believe that tektites are formed by the impact of large meteors on the Earth's surface. These impacts would shoot sand rock, and other debris way up in the atmosphere. When this debris fell from the sky and came back to the surface, it was superheated and changed during re-entry. Pieces could fall to the Earth hundreds of miles from the impact sight.