|Structural classification||Coarse Octahedrite|
|Composition||90.5% Fe; 8.1% Ni|
|Region||Toluca Valley, Jiquipilco, Mexico State|
|Fall date||>10,000 years ago|
|Found date||about 1776|
|Related media on Wikimedia Commons|
Toluca is a shower of iron meteorites found in Jiquipilco, Mexico near Toluca.
The meteorites crashed towards the Earth more than 10,000 years earlier.For centuries, Mexican people living near the meteorites used them as a source of metal for various tools. They were seen by conquistadores about 1776.
The total known mass is about 3 tonnes.
These iron meteorites are a coarse octahedrite, chemical type IAB-sLL.The mean composition is 90.5% Fe and 8.1% Ni. They often contain large troilite inclusions.
Octahedrites are the most common structural class of iron meteorites. The structures occur because the meteoric iron has a certain nickel concentration that leads to the exsolution of kamacite out of taenite while cooling.
Cementite (or iron carbide) is a compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula Fe3C. By weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure. It is a hard, brittle material, normally classified as a ceramic in its pure form, and is a frequently found and important constituent in ferrous metallurgy. While cementite is present in most steels and cast irons, it is produced as a raw material in the iron carbide process, which belongs to the family of alternative ironmaking technologies. The name cementite originated from the theory of Floris Osmond and J. Werth, in which the structure of solidified steel consists of a kind of cellular tissue, with ferrite as the nucleus and Fe3C the envelope of the cells. The carbide therefore cemented the iron.
Wüstite (FeO) is a mineral form of iron(II) oxide found with meteorites and native iron. It has a grey colour with a greenish tint in reflected light. Wüstite crystallizes in the isometric-hexoctahedral crystal system in opaque to translucent metallic grains. It has a Mohs hardness of 5 to 5.5 and a specific gravity of 5.88. Wüstite is a typical example of a non-stoichiometric compound.
Campo del Cielo refers to a group of iron meteorites and the area in Argentina where they were found. The site straddles the provinces of Chaco and Santiago del Estero, located 1,000 kilometers (620 mi) north-northwest of Buenos Aires, Argentina and approximately 500 kilometres (310 mi) southwest of Asunción, Paraguay. The crater field covers 18.5 by 3 kilometres and contains at least 26 craters, the largest being 115 by 91 metres.
An iron meteorite fell on the Sikhote-Alin Mountains, in southeastern Russia, in 1947. Large iron meteorite falls have been witnessed and fragments recovered but never before, in recorded history, a fall of this magnitude. An estimated 23 tonnes of fragments survived the fiery passage through the atmosphere and reached the Earth.
The Willamette Meteorite, officially named Willamette and originally known as Tomanowos by the Clackamas Chinook Native American tribe, is an iron-nickel meteorite found in the U.S. state of Oregon. It is the largest meteorite found in the United States and the sixth largest in the world. There was no impact crater at the discovery site; researchers believe the meteorite landed in what is now Canada or Montana, and was transported as a glacial erratic to the Willamette Valley during the Missoula Floods at the end of the last Ice Age. It has long been held sacred by indigenous peoples of the Willamette Valley, including the federally recognized Confederated Tribes of the Grand Ronde Community of Oregon (CTGRC).
Widmanstätten patterns, also known as Thomson structures, are figures of long nickel–iron crystals, found in the octahedrite iron meteorites and some pallasites. They consist of a fine interleaving of kamacite and taenite bands or ribbons called lamellae. Commonly, in gaps between the lamellae, a fine-grained mixture of kamacite and taenite called plessite can be found. Widmanstätten patterns describe features in modern steels, titanium, and zirconium alloys.
The Cape York meteorite, also known as the Innaanganeq meteorite, is one of the largest known iron meteorites, classified as a medium octahedrite in chemical group IIIAB. In addition to many small fragments, at least eight large fragments with a total mass of 58 tons have been recovered, the largest weighing 31 tonnes. The meteorite is named after the location where the largest fragment was found: 23 miles (37 km) east of Cape York, in Savissivik, Meteorite Island, Greenland.
Cohenite is a naturally occurring iron carbide mineral with the chemical structure (Fe, Ni, Co)3C. This forms a hard, shiny, silver mineral which was named by E. Weinschenk in 1889 after the German mineralogist Emil Cohen, who first described and analysed material from the Magura meteorite found near Slanica, Žilina Region, Slovakia. Cohenite is found in rod-like crystals in iron meteorites.
Meteoric iron, sometimes meteoritic iron, is a native metal and early-universe protoplanetary-disk remnant found in meteorites and made from the elements iron and nickel, mainly in the form of the mineral phases kamacite and taenite. Meteoric iron makes up the bulk of iron meteorites but is also found in other meteorites. Apart from minor amounts of telluric iron, meteoric iron is the only naturally occurring native metal of the element iron on the Earth's surface.
Ataxites are a structural class of iron meteorites with a high nickel content and show no Widmanstätten patterns upon etching.
Hexahedrites are a structural class of iron meteorite. They are composed almost exclusively of the nickel–iron alloy kamacite and are lower in nickel content than the octahedrites. The nickel concentration in hexahedrites is always below 5.8% and only rarely below 5.3%.
Troilite is a rare iron sulfide mineral with the simple formula of FeS. It is the iron-rich endmember of the pyrrhotite group. Pyrrhotite has the formula Fe(1-x)S which is iron deficient. As troilite lacks the iron deficiency which gives pyrrhotite its characteristic magnetism, troilite is non-magnetic.
Iron meteorites, also called siderites or ferrous meteorites, are a type of meteorite that consist overwhelmingly of an iron–nickel alloy known as meteoric iron that usually consists of two mineral phases: kamacite and taenite. Most iron meteorites originate from cores of planetesimals, with the exception of the IIE iron meteorite group
Noric steel was a steel from Noricum, a kingdom located in modern Austria and Slovenia.
Toluca is a city in Mexico.
Gibeon is a meteorite that fell in prehistoric times in Namibia. It was named after the nearest town: Gibeon.
Telluric iron, also called native iron, is iron that originated on Earth, and is found in a metallic form rather than as an ore. Telluric iron is extremely rare, with only one known major deposit in the world, located in Greenland.
The Mundrabilla meteorite is an iron meteorite found in 1911 in Australia, one of the largest meteorites found, with a total known weight of 22 tonnes and the main mass accounting for 12.4 tonnes.
Monturaqui is an impact crater in Chile. It lies south of the Salar de Atacama and was formed 663,000 ± 90,000 years ago by the impact of an IAB meteorite. It is 350 m × 370 m wide and 34 m (112 ft) deep and contains a salt pan. Only a few remnants of the meteorite that formed the crater have been collected, with most of the rocks being of local origin. The crater was discovered in 1962 and identified as an impact crater in 1966.