tektite

tektite , naturally occurring, silica-rich (65%-80% SiO ₂ ) glass resembling obsidian and sometimes shale, and is normally jet black to olive green. They appear as small rounded or elongated objects that often have aerodynamic shapes and range from a fraction of an ounce to several pounds in weight. They are found in limited areas on the earth's surface called strewn fields (in contrast to meteorites, which show a random distribution over the whole earth). Tektites, originally named by Eduard Suess are usually given a name derived from the region in which they are found; moldavites (from the Vlatava, or Moldau, River in the Czech Republic), bediasites (from the territory of the Bedias Native Americans in Texas), indochinites, philippinites, australites, javanites, and Côte d'Ivoire tektites are the principal groups. Their peculiar composition, physical characteristics, and restricted geographic distribution gave rise to several theories: one suggests a lunar origin, i.e., that they were the result of a lunar meteorite impact that ejected splashes of molten lunar rock, some of which eventually made their way to earth; however, the composition of moon rocks does not resemble tektites, and the lunar-origin theory, for the most part, is questionable. Another theory suggests their origin to be through the fusion and ejection of terrestrial material by the impact of giant meteorites or comets on the earth; the moldavites and the Côte d'Ivoire tektites have been linked with such impacts, but the source of the remaining tektite groups is still uncertain.

tektite A small, glassy object 1–30 mm in size, usually dark green, brown, or black. Tektites are scattered over certain areas of the Earth's surface, often in vast strewn fields. They are 0.75–65 million years old and have a variety of shapes, including spheroids, dumbbells, droplets, lenses, and disks. The word ‘tektite’ is derived from the Greek word tektos, meaning ‘melted’. They were probably formed from molten material splashed into space by meteorite impacts on Earth. This material later condensed into droplets and re-entered the atmosphere, undergoing ablation. Tektites are named according to the area in which they are found, for example australites (Australia and Tasmania), bediasites (Texas, USA), billitonites (Billiton Island, Indonesia), georgiaites (Georgia, USA), indochinites (former Indo-China), malaysianites (Malaysia), moldavites (Czech Republic), and philippinites (Philippine Islands).