Mesosiderites are a class of

stony–iron meteorite Stony-iron meteorites or siderolites are meteorites that consist of nearly equal parts of meteoric iron and silicates. This distinguishes them from the stony meteorites, that are mostly silicates, and the iron meteorites, that are mostly meteori ...

s consisting of about equal parts of metallic nickel-iron and silicate. They are

breccia Breccia () is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language, in whi ...

s with an irregular texture; silicates and metal occur often in lumps or pebbles as well as in fine-grained intergrowths. The silicate part contains

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quic ...

pyroxenes The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) ...

, and Ca-rich

feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feld ...

and is similar in composition to

eucrite Eucrites are achondritic stony meteorites, many of which originate from the surface of the asteroid 4 Vesta and are part of the HED meteorite clan. They are the most common achondrite group with over 100 meteorites found. Eucrites consist of b ...

s and

diogenite Diogenites are a group of the HED meteorite clan, a type of achondritic stony meteorites. Origin and composition Diogenites are currently believed to originate from deep within the crust of the asteroid 4 Vesta, and as such are part of the HED ...

s. They are a rare type of meteorite; as of November 2014 only 208 are known (of which 56 come from Antarctica) and only 7 of these are observed falls. On the other hand, some mesosiderites are among the largest meteorites known. At Vaca Muerta in the

Atacama Desert The Atacama Desert ( es, Desierto de Atacama) is a desert plateau in South America covering a 1,600 km (990 mi) strip of land on the Pacific coast, west of the Andes Mountains. The Atacama Desert is the driest nonpolar desert in the w ...

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

, many fragments with a total mass of 3.8 tons were found in a large

strewnfield The term strewn field indicates the area where meteorites from a single fall are dispersed. It is also often used for the area containing tektites produced by large meteorite impact.''Tektites in the geological record: showers of glass from the sk ...

. They were first discovered in the 19th century by ore

prospector Prospector may refer to: Space exploration * Prospector (spacecraft), a planned lunar probe, canceled in 1962 * ''Lunar Prospector'', a NASA spacecraft Trains * Prospector (train), a passenger train operated by the Denver & Rio Grande Western ...

s who mistook the shiny metal inclusions for

silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...

and thought they had found an outcrop of a silver ore deposit. Later when an analysis was made and nickel-iron was found, the true nature as a meteorite was established. The meteorite was called Vaca Muerta. The picture at right shows a cut and polished piece of Vaca Muerta. The most recent fall of a mesosiderite occurred at Dong Ujimqin Qi in China, on September 7, 1995, where three large pieces with a total mass of fell. The fall of the Estherville mesosiderite in Iowa, US occurred on May 10, 1879. After a brilliant fireball had been seen, a shower of several large masses and many small fragments fell, totaling . The fall at Lowicz in Poland on March 12, 1935, yielded many (more than 50) fragments with a total weight of . The other observed mesosiderite falls occurred in 1842 at Barea (Spain), in 1880 at Varamin (Iran), in 1933 at Dyarrl Island (Papua New Guinea), and at Patwar (India) in 1935.The Meteoritical Bulletin Database, http://www.lpi.usra.edu/meteor/metbull.php The legendary

Chinguetti meteorite The Chinguetti meteorite is a find reputed to come from a large unconfirmed 'iron mountain' in Africa. The existence of a huge stony-iron mesosiderite approximately 45 kilometers from the Saharan city Chinguetti, Mauritania, has been a mystery sin ...

is also supposed to be a mesosiderite. The asteroid

16 Psyche 16 Psyche () is a large M-type asteroid discovered by the Italian astronomer Annibale de Gasparis on 17 March 1852 and named after the Greek goddess Psyche. The prefix "16" signifies that it was the sixteenth minor planet in order of ...

is a candidate for the parent body of the mesosiderites.

References

External links

Mesosiderite images
from Northern Arizona University

from Meteorites Australia {{Meteorites

See also

References

External links