Australites are tektites found in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. They are mostly dark or black, and have shapes including discs and bowls that are not seen in other tektites. NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 used the shape of "flanged button" australites in designing re-entry modules for the Apollo program in the 1960s.

History

Indigenous Australians

Indigenous Australians

Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....

 termed australites ooga ("staring eyes"), and they were used as sacred objects or as cutting tools. Europeans found out about australites in 1857, when explorer Thomas Mitchell gave naturalist Charles Darwin

Charles Darwin

Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 a mysteriously shaped piece of natural black glass. Darwin thought that australites were of volcanic

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 origin due to their similarity to obsidian

Obsidian

Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock.It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth...

, volcanic glass. Later, australites were called blackfellows' buttons and obsidian bombs.

One of the first scientists to seriously study australites was Charles Fenner, who saw his first australite in 1907. He believed that australites were glass meteorite

Meteorite

A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...

s.

Origin

Early theories about the source of australites included volcanoes, the bushfires that are common in Australia, or fusion of sand by lightning (fulgurite

Fulgurite

Fulgurites are natural hollow glass tubes formed in quartzose sand, or silica, or soil by lightning strikes. They are formed when lightning with a temperature of at least instantaneously melts silica on a conductive surface and fuses grains together; the fulgurite tube is the cooled product...

s). Some scientists believed them to be meteorites, possibly lunar meteorite

Lunar meteorite

A Lunar meteorite is a meteorite that is known to have originated on the Moon.-Discovery:In January 1982, John Schutt, leading an expedition in Antarctica for the ANSMET program, found a meteorite that he recognized to be unusual...

s ejected from the Moon in impact

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

s (now disproved due to the different composition of lunar rocks).

Although different theories about the origin of australites are still circulating, 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

Australasian strewnfield

The Australasian strewnfield, covering at least one-tenth of the Earth's surface, is the largest and the youngest of the tektite strewnfields. The 800,000 year-old strewnfield includes most of Southeast Asia...

 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.

Shapes

The primary forms of australites are sphere, oval, boat, dumbbell and teardrop. Australites are smaller and different in shape to other tektites. Their initial velocity was higher than other tektites: enough to propel them just out of the Earth's atmosphere, so they then re-entered the atmosphere and underwent a rare secondary melting.

One of the most famous australite shapes is the "flanged button". Flanged buttons are rare, but the most unusual and rarest australites are discs, bowls, plates and other small forms (mini tektites). They are very thin. George Baker called them "flying flanges", the result of distortion of "initially small primary forms by aerodynamic frictional heating". He wrote: Well preserved shapes are found near Port Cambell in Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

.

Chapman and Larson experimented on the ablation

Ablation

Ablation is removal of material from the surface of an object by vaporization, chipping, or other erosive processes. This occurs in spaceflight during ascent and atmospheric reentry, glaciology, medicine, and passive fire protection.-Spaceflight:...

 of australites. At first they seemed to prove their extraterrestrial

Extraterrestrial life

Extraterrestrial life is defined as life that does not originate from Earth...

 origin, but later in repeated studies they claimed that the australites could not have come from outside the Earth-Moon system. They were able to reproduce the shapes, flange

Flange

A flange is an external or internal ridge, or rim , for strength, as the flange of an iron beam such as an I-beam or a T-beam; or for attachment to another object, as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera; or for a flange of a rail car or tram wheel...

s and the peculiar network of the rings on the front face in great detail.