Tektite

Tektites (from Greek  , "molten") are gravel-sized bodies of natural glass. They come in green or brown (usually). They are formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz Eduard Suess (1867–1941). They generally range in size from millimeters to centimeters. Millimeter-scale tektites are known as microtektites.French B.M. 1998. Traces of catastrophe: a handbook of shock-metamorphic effects in terrestrial meteorite impact structures. LPI Contribution No. 954. Lunar and Planetary Institute, Houston, Texas.McCall G.J.H. 2001. Tektites in the geological record: showers of glass from the sky. The Geological Society Bath, United Kingdom.  Montanari A. and C. Koeberl 2000. Impact stratigraphy. The Italian record. Lecture Notes in Earth Sciences Series no. 93. Springer-Verlag,  New York. 

Tektites are characterized by:
 a fairly homogeneous composition
 an extremely low content of water and other volatiles
 an abundance of lechatelierite (silica glass, amorphous SiO2)
 a general lack of microscopic crystals known as microlites and chemical relation to the local bedrock or local sediments
 their distribution in widespread strewn fields

 Related pages 
 Meteorite strewnfield

 References 

Category:Impact events
Category:Glass
Category:Unclassified minerals