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ITUTINGA
Iron
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DESCRIPTION:
ACHONDRITE
MEDIUM OCTAHEDRITE
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IIIAB
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BRAZIL - MG
1960
Iron Meteorite - IIIAB Medium Octahedrite.
PETROGRAPHY:
Analyzes of the Mössbauer spectrum of the polished face of this possible fragment of the Itutinga meteorite revealed the presence of two FeNi, kamacite phases (alpha-FeNi) and taenite (gamma-FeNi). In the meteorite fragment, the existence of the plessite phase was also identified. After a chemical attack on the surface, revealing the Widmanstätten pattern, the linear measurements of the average width of the kamacite lamellae of this meteorite, with about 1.0mm, are compatible with the Itutinga meteorite lamellae (Grady, 2000) and with the corresponding interval to the medium octahedrite. (0.5 to 1.3mm) relative to the structural classification. Source: Nunes et al. (2010).
GEOCHEMISTRY:
Ni (7.2%), Ga (18.6ppm), Ge (36.0ppm), Ir (13.0ppm). Source: Grady et al. (2000).
CLASSIFICATION:
Due to the existing correspondence between the structural and chemical classification, iron meteorites of the medium octahedrite class belong to the IIIAB group in terms of chemical classification (Sears, 1978). Source: Nunes et al. (2010).
CLASSIFIERS:
Not reported by the Meteoritical Bulletin Database. The only reference found for the entrance to Itutinga is in Buchwald (1975).
HISTORY:
Itutinga was known only that the meteorite weighed more than 4 kg, had no fusion crust and that it had been found before 1960, near the city of Itutinga, according to information published by Buchwaldt in 1975. After a meticulous research at the Museum Nacional, an annotation was found, in which it informed that the meteorite had been found in a place called Barro Preto at 2 km NW of Itutinga, in the lands of Mr. Américo Leite. When visiting the city where the meteorite was found, after several interviews with the oldest sites, it was discovered that the land was a closed farm, explored by Dr. Silvio, whose mother-in-law had lived there at the time the stone was found. According to her, the stone was found near a stream, by Mr. Antônio Lampião, who unfortunately did not remember anything. There were many streams in the region and it would be difficult to find the right stream. Finally, after much questioning among the older people in the city, luckily Mr. Nelson met who returned to the find site the next day with the whole team. Mr. Nelson said it was the strange stone attached to a donkey and dragged to the farm's old headquarters - now demolished, where it remained on the doorstep like a bank for several years, until the news of his discovery reached the Ouro Preto Mine School, where it ended up being donated by Dr. José Carlos Ferreira Gomes. At the Ouro Preto Museum, it was found that the main mass appears to be from the Itumirim meteorite, without any data on its history, nor even records of its entry into the Museum, its mass being identical to an old photo without references , found in the National Museum of Rio de Janeiro and that the piece that was in the National Museum seemed to fit perfectly with the cut made in the meteorite. At the time it was not possible to access the piece, which can only be seen through the window and without being able to photograph. The main mass in Ouro Preto, referring to the meteorite as Itumirim, this is due to the fact that the meteorite was donated in 1947 and Itutinga only became a Municipality in 1953. The sample of the National Museum arrived in 1960 when the Itutinga municipality already existed. This fact probably caused the duality of names, also called synonymy. Description obtained in the documents of National Museum.
All information that does not have a specific source was extracted from the Meteoritical Bulletin Database.
All images are copyrighted.
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