Tektites

Tektites (from Greek τηκτός tēktós, "molten") are gravel-sized bodies composed of black, green, brown, or gray natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz Eduard Suess (1867–1941), son of Eduard Suess. They generally range in size from millimeters to centimeters. Millimeter-scale tektites are known as microtektites.

Tektites are characterized by:
 * 1) a fairly homogeneous composition
 * 2) an extremely low content of water and other volatiles
 * 3) an abundance of lechatelierite
 * 4) a general lack of microscopic crystals known as microlites and chemical relation to the local bedrock or local sediments
 * 5) their distribution within geographically extensive strewn fields

Australites
Australites are tektites found in Australia. They are mostly dark or black, and have shapes including discs and bowls that are not seen in other tektites. NASA used the shape of "flanged button" australites in designing re-entry modules for the Apollo program in the 1960s.

Most scientists believe that australites formed during a large asteroid or comet impact on the Earth. The impact ejected myriads of small rocks right out of the atmosphere. The australites acquired their streamlined, aerodynamic forms when they re-entered the Earth's atmosphere while molten and travelling at high velocities.

Most australites are found in Southern Australia, below 25 degrees latitude. Based on similar ages and compositions, they represent the southern edge of the vast Australasian tektite strewnfield that stretches from southern China to Australia. The Australasian strewnfield has an age of 0.8 million years and is the result of an impact in Indochina.