|
IIG Meteorites
IIG meteorites are a group of iron meteorites. The group currently has six members. They are hexahedrites with large amounts of schreibersite. The meteoric iron is composed of kamacite. Naming and history Iron meteorites are designated with a Roman numeral and one or two letters. Classification is based on diagrams in which nickel content of meteoric iron is plotted against trace elements. Clusters in these diagrams are assigned a row (Roman numeral) and a letter in alphabetical order. IIG meteorites are therefore from the second row, cluster G. The Bellsbank, La Primitiva and Tombigbee meteorites were iron meteorites that were found to have chemical and structural similarities in 1967. Further descriptions were made in 1973 and in 1974 it was proposed that the three meteorites should be grouped into the "Bellsbank Trio" grouplet. The group status, that requires five specimen was filled in 1984 by the Twannberg meteorite and in 2000 by the Guanaco meteorite. Description IIG ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magmatic
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and gas bubbles. Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by fractional crystallization, contamination with crustal melts, magma mixing, and degassing. Following its ascent through the crust, magma may feed a volcano and be extruded as lava, or it may solidify underground to form an intrusion, such as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
La Primitiva Meteorite
LA most frequently refers to Los Angeles, the second largest city in the United States. La, LA, or L.A. may also refer to: Arts and entertainment Music * La (musical note), or A, the sixth note * "L.A.", a song by Elliott Smith on ''Figure 8'' (album) * ''L.A.'' (EP), by Teddy Thompson * ''L.A. (Light Album)'', a Beach Boys album * "L.A." (Neil Young song), 1973 * The La's, an English rock band * L.A. Reid, a prominent music producer * Yung L.A., a rapper * Lady A, an American country music trio * "L.A." (Amy Macdonald song), 2007 * "La", a song by Australian-Israeli singer-songwriter Old Man River Other media * l(a, a poem by E. E. Cummings * La (Tarzan), fictional queen of the lost city of Opar (Tarzan) * ''Lá'', later known as Lá Nua, an Irish language newspaper * La7, an Italian television channel * LucasArts, an American video game developer and publisher * Liber Annuus, academic journal Business, organizations, and government agencies * L.A. Screenings, a te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetesimal
Planetesimals are solid objects thought to exist in protoplanetary disks and debris disks. Per the Chamberlin–Moulton planetesimal hypothesis, they are believed to form out of cosmic dust grains. Believed to have formed in the Solar System about 4.6 billion years ago, they aid study of its formation. Formation A widely accepted theory of planet formation, the so-called planetesimal hypotheses, the Chamberlin–Moulton planetesimal hypothesis and that of Viktor Safronov, states that planets form from cosmic dust grains that collide and stick to form ever-larger bodies. Once a body reaches around a kilometer in size, its constituent grains can attract each other directly through mutual gravity, enormously aiding further growth into moon-sized protoplanets. Smaller bodies must instead rely on Brownian motion or turbulence to cause the collisions leading to sticking. The mechanics of collisions and mechanisms of sticking are intricate. Alternatively, planetesimals may form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IIAB Meteorites
IIAB meteorites are a group of iron meteorites. Their structural classification ranges from hexahedrites to octahedrites. IIABs have the lowest concentration of nickel of all iron meteorite groups. Most iron meteorites are derived from the metallic planetary cores of their respective parent bodies, but in the case of the IIABs the metallic magma separated to form not only this meteorite group but also the IIG group. Naming Iron meteorite groups are designated with a Roman numeral and one or two letters. Classification is based on diagrams in which the nickel content of meteoric iron is plotted against certain trace elements (e.g. gallium, germanium and iridium). Clusters in these diagrams are assigned a row (Roman numeral) and a letter in alphabetical order. The first two cluster of the second row, IIA and IIB, were merged when additional measurements connected the two clusters into one, the IIAB group. Description All iron meteorites are made of a native metal called meteor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to react with air under standard conditions because a passivation layer of nickel oxide forms on the surface that prevents further corrosion. Even so, pure native nickel is found in Earth's crust only in tiny amounts, usually in ultramafic rocks, and in the interiors of larger nickel–iron meteorites that were not exposed to oxygen when outside Earth's atmosphere. Meteoric nickel is found in combination with iron, a reflection of the origin of those elements as major end products of supernova nucleosynthesis. An iron–nickel mixture is thought to compose Earth's outer and inner cores. Use of nickel (as natural meteoric nickel–iron alloy) has been traced as far back as 3500 BCE. Nickel was first isolated and classified as an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanaco Meteorite
The guanaco (; ''Lama guanicoe'') is a camelid native to South America, closely related to the llama. Guanacos are one of two wild South American camelids, the other being the vicuña, which lives at higher elevations. Etymology The guanaco gets its name from the Quechua word ''huanaco'' (modern spelling ''wanaku''). Young guanacos are called ''chulengos''. Characteristics Guanacos stand between at the shoulder, body length of , and weigh . Their color varies very little (unlike the domestic llama), ranging from a light brown to dark cinnamon and shading to white underneath. Guanacos have grey faces and small, straight ears. The lifespan of a guanaco can be as long as 28 years. Guanacos are one of the largest terrestrial mammals native to South America today.San Diego Zoo's Animal Bytes Other terrestrial mammali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twannberg Meteorite
The Twannberg meteorite is a hexahedrite iron meteorite. It is the only meteorite of the IIG meteorites, IIG group found in Europe and the largest meteorite ever found in Switzerland. Discovery and naming The first fragment () was found on 9 May 1984 in a barley field near Twann, after it had been ploughed (Twannberg I). Two additional fragments were found in an unnatural setting. One fragment (II) was found in 2000 in an attic in Twann and another (III) in 2005 in the Natural History Museum of Bern, Naturhistorisches Museum Bern, in a collection received from the Museum Schwab in Biel where it had been labeled as hematite around 1930. Twannberg IV, V and VI were found in the creek Twannbach. The meteorite is named after Twannberg (from German: Twann mountain), a mountain that lies north of Twann. The find location is a glacial till deposit. This paired with minerals found in the oxidized surface of the meteorite are an indicator that the meteorite fell on the Rhone glacier and w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tombigbee Meteorite
The Tombigbee River is a tributary of the Mobile River, approximately 200 mi (325 km) long, in the U.S. states of Mississippi and Alabama. Together with the Alabama, it merges to form the short Mobile River before the latter empties into Mobile Bay on the Gulf of Mexico. The Tombigbee watershed encompasses much of the rural coastal plain of western Alabama and northeastern Mississippi, flowing generally southward. The river provides one of the principal routes of commercial navigation in the southern United States, as it is navigable along much of its length through locks and connected in its upper reaches to the Tennessee River via the Tennessee-Tombigbee Waterway. The name "Tombigbee" comes from Choctaw ''/itumbi ikbi/'', meaning "box maker, coffin maker", from ''/itumbi/'', "box, coffin", and ''/ikbi/'', "maker". The river formed the eastern boundary of the historical Choctaw lands, from the 17th century when they coalesced as a people, to the forced Indian Rem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bellsbank Meteorite
The Bellsbank meteorite is a hexahedrite iron meteorite with abundant schreibersite. It is classified as a member of the IIG group. It was found in Bellsbank, South Africa in 1955. Discovery and naming The meteorite was found in 1955 near Bellsbank (), northwest of Kimberley ( South Africa). Only one specimen with a mass of was dug out from a field. The meteorite was first described in 1959. Description The meteorite is hexahedrite iron meteorite. It consists of meteoric iron (exclusively kamacite) and schreibersite. The surface of the meteorite is pitted and weathered. Upon etching the meteorite shows Neumann lines. The meteoric iron has Nickel concentrations as low as 1.6%. Classification The Bellsbank meteorite was the type specimen of the grouplet In meteoritics, a meteorite classification system attempts to group similar meteorites and allows scientists to communicate with a standardized terminology when discussing them. Meteorites are classified according to a va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexahedrite
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%. The name comes from the cubic (i.e. ''hexahedron'') structure of the kamacite crystal. After etching, hexahedrites do not display a Widmanstätten pattern, but they often do show Neumann lines: parallel lines that cross each other at various angles, and are indicative of impact shock on the parent body. These lines are named after Johann G. Neumann, who discovered them in 1848. Chemical classification Concentrations of trace elements (germanium, gallium and iridium) are used to separate the iron meteorites into chemical classes, which correspond to separate asteroid parent bodies. Chemical classes that include hexahedrites are: * IIAB meteorites (includes also some octahedrites) * IIG meteorites See also * Glos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
