| 词条 | Mesosiderite |
| 释义 |
|Subdivision = Class |Name = Mesosiderite |Alternative names = |Image = Vaca muerta mesosiderite.jpg |Image_caption = Vaca muerta mesosiderite. |Type = Stony-iron |Class = |Clan = |Subgroups = {{flatlist|
}} |Structural_classification = |Parent_body = |Composition = Meteoric iron (kamacite, taenite & tetrataenite); silicates (mostly pyroxene & Ca-rich plagioclase); sulphides (troilite) |Number_of_specimens = 208 |TKW = |Image2 = Chinguetti meteorite.jpg |Image2_caption = Chinguetti mesosiderite }}Mesosiderites are a class of stony–iron meteorites consisting of about equal parts of metallic nickel-iron and silicate. They are breccias 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, pyroxenes, and Ca-rich feldspar and is similar in composition to eucrites and diogenites.[1][2] 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 in Chile, many fragments with a total mass of 3.8 tons were found in a large strewnfield. They were first discovered in the 19th century by ore prospectors who mistook the shiny metal inclusions for silver 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.[3] 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 {{convert|129|kg}} 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 {{convert|320|kg}}. The fall at Lowicz in Poland on March 12, 1935 yielded many (more than 50) fragments with a total weight of {{convert|59|kg}}. 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.[4] The legendary Chinguetti meteorite is also supposed to be a mesosiderite. The asteroid 16 Psyche is a candidate for the parent body of the mesosiderites.[5] See also
References1. ^F. Heide, F. Wlotzka: Meteorites, Messengers from Space. Springer Verlag 1985. 2. ^Karl K. Turekian. Meteorites, comets, and planets, [https://books.google.com/books?id=kYtksEUxw0oC&lpg=PA112&dq=mesosiderite&pg=PA112#v=onepage&q=mesosiderite&f=false Page 112] 3. ^H. Pedersen et al., Meteoritics 27 (1992) 126 4. ^The Meteoritical Bulletin Database, http://www.lpi.usra.edu/meteor/metbull.php 5. ^{{cite journal | first1= D. R. | last1=Davis | first2= Paolo | last2=Farinella | first3= M. | last3=Francesco | last-author-amp= yes| title= The Missing Psyche Family: Collisionally Eroded or Never Formed?| journal= Icarus| date= 1999| volume= 137 | issue= 1| page= 140 | doi = 10.1006/icar.1998.6037 | bibcode=1999Icar..137..140D}} External links{{Commons category|Mesosiderites}}
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