Muonionalusta
Encyclopedia
The Muonionalusta is a meteorite
classified as fine octahedrite
, type IVA (Of). The first fragment of the Muonionalusta was found in 1906 in a 25 x 15 km area approximately 140 km north of the Artic Circle, in the Pajala district, Norbbotten, Sweden
. Around fourty pieces are known today, some being quite large.
It was first described in 1910 as Muonionalusta, therefore named after the municipality of Muonio
, by professor A. G. Högbom and studied in 1948 by Professor Nils Göran David Malmqvist
. The Munionalusta, probably the oldest meteorite known to man, marks the first occurence of stishivite in an iron meteorite.
period, about one million years ago. It is quite clearly part of the iron core or mantle of a planetoid, which shattered into many pieces upon its fall on our planet. Since landing here this meteorite has experienced four ice ages. It was unearthed from a glacial moraine in the northern tundra
. A strongly weathered surface covered with cemented facetted pebbles leaves no doubt that its sojourn on Earth has been long and dramatic.
and trace amounts of rare elements - 0.33% ppm gallium
, 0.133% ppm germanium
and 1.6 ppm iridium
. It also contains the common minerals chromite
, Daubreélite, schreibersite
, Akaganéite
and inclusions of troilite
. For the first time, analysis has proved the presence of a form of quartz
altered by extremely high pressure - stishovite
, probably a pseudomorphosis after tridymite
.
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...
classified as fine octahedrite
Octahedrite
Octahedrites are a class of iron meteorites within the structural classification. They are the most common class of iron meteorites.They are composed primarily of the nickel-iron alloys: taenite - high nickel content, and kamacite - low nickel content....
, type IVA (Of). The first fragment of the Muonionalusta was found in 1906 in a 25 x 15 km area approximately 140 km north of the Artic Circle, in the Pajala district, Norbbotten, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
. Around fourty pieces are known today, some being quite large.
It was first described in 1910 as Muonionalusta, therefore named after the municipality of Muonio
Muonio
Muonio is a municipality of Finland.It is located in the province of Lapland. The municipality has a population of and covers an area of of which is water. The population density is...
, by professor A. G. Högbom and studied in 1948 by Professor Nils Göran David Malmqvist
Göran Malmqvist
Professor Nils Göran David Malmqvist is a Swedish linguist, member of the Swedish Academy , literary historian, sinologist and translator.-Biography:...
. The Munionalusta, probably the oldest meteorite known to man, marks the first occurence of stishivite in an iron meteorite.
Description
Studies have shown it to be the oldest discovered meteorite impacting the Earth during the QuaternaryQuaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
period, about one million years ago. It is quite clearly part of the iron core or mantle of a planetoid, which shattered into many pieces upon its fall on our planet. Since landing here this meteorite has experienced four ice ages. It was unearthed from a glacial moraine in the northern tundra
Tundra
In physical geography, tundra is a biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sami word tūndâr "uplands," "treeless mountain tract." There are three types of tundra: Arctic tundra, alpine...
. A strongly weathered surface covered with cemented facetted pebbles leaves no doubt that its sojourn on Earth has been long and dramatic.
Composition
New analysis of this strongly shock-metamorphosed iron meteorite has shown a content of 8.4% nickelNickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
and trace amounts of rare elements - 0.33% ppm gallium
Gallium
Gallium is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the gallium salt in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies...
, 0.133% ppm germanium
Germanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. The isolated element is a semiconductor, with an appearance most similar to elemental silicon....
and 1.6 ppm iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
. It also contains the common minerals chromite
Chromite
Chromite is an iron chromium oxide: FeCr2O4. It is an oxide mineral belonging to the spinel group. Magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite ; substitution of aluminium occurs leading to hercynite .-Occurrence:Chromite is found in...
, Daubreélite, schreibersite
Schreibersite
Schreibersite is generally a rare iron nickel phosphide mineral, 3P, though common in iron-nickel meteorites. It is rarely reported from Earth . Another name used for the mineral is rhabdite. It forms tetragonal crystals with perfect 001 cleavage. Its color ranges from bronze to brass yellow to...
, Akaganéite
Akaganéite
Akaganéite is an iron oxide-hydroxide / chloride mineral with formula: Fe3+O e.g; β-FeO. It is formed by the weathering of pyrrhotite . Nickel also has been reported in the structure. It has a monoclinic crystal structure, a metallic luster and a brownish yellow streak. It is named after the...
and inclusions of troilite
Troilite
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 FeS which is iron deficient...
. For the first time, analysis has proved the presence of a form of quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
altered by extremely high pressure - stishovite
Stishovite
Stishovite is an extremely hard, dense tetragonal form of silicon dioxide. It was long considered the hardest known oxide; however, boron suboxide has recently been discovered to be much harder...
, probably a pseudomorphosis after tridymite
Tridymite
Tridymite is a high-temperature polymorph of quartz and usually occurs as minute tabular white or colorless pseudo-hexagonal triclinic crystals, or scales, in cavities in acidic volcanic rocks. Its chemical formula is SiO2. Tridymite was first described in 1868 and the type location is in Hidalgo,...
.
Distribution
- Geological Institute, Uppsala, 15 kg.
- NHM, Vienna, 96 gr.
- MIN, Berlin, 82 gr.
- MPI, Mainz, 96.3 gr.
- Paneth Colln. Mainz, 142.5 gr.
- USNM, Washington, 197 gr.
- AMNH, New York, 84 gr.
- FMNH, Chicago, 65.2 gr.
- UCLA, Los Angeles, 55 gr.
Source
- Malmqvist, David: Structure of the Muonionalusta iron meteorite and a method of determining the orientation of lamellae of octahedrites, Almquist & Wiksells, Uppsala (1948),
External links
- Muonionalusta at The Meteoritical Society Website