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.
Tektites are characterized by: