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S1 or more
BRAZIL - MG
Equilibrated Ordinary Chondrite L6 with signs of shock stage.
The meteorite exhibits a texture with high recrystallization, with only a few discernible chondrules in the middle of the matrix. The visible chondrules are round and vary in internal texture (porphyritic, poikilitic, etc.). The meteorite also has textural and mineralogical characteristics that have suffered shock events.
According to Keil et al. (1962a, b), studying polished sections of Minas Gerais, the meteorite is composed of 87.96% silicates, 8.03% FeNi, 3.75% troilite and 0.26% chromite. The normative composition indicates 84.9%, 8.5%, 5.3% and 0.9% of these minerals, respectively. Ramdohr (1973) describes chalcopyrite, mackinawite and ilmenite as accessory minerals. Olivine Fa25 and low-Ca pyroxene Fs20, with less interstitial plagioclase, represent the silicate portion of the meteorite. Source: Gomes & Keil (1980).
The classification for the chemical L group was first suggested by Keil (1962b), based on the compositions of olivine and low-Ca pyroxene. This classification is confirmed by the total chemistry and the Feº / Ni (5.28), Fe / SiO2 (0.57) and Feº / Fe (0.32) ratios, as well as the total Fe concentration in the meteorite (22.31%) and total FeNi of 8.47%. The type 6 petrographic classification, according to Van Schmus & Wood (1967), is due to the high recrystallization of the matrix, with grains of clear and interstitial plagioclase, very poorly defined chondritic texture and the compositional homogeneity of olivines and pyroxenes. Source: Gomes & Keil (1980).
Not reported by the Meteoritical Bulletin Database. According to Gomes & Keil (1980), who classified the Minas Gerais meteorite was Oliveira (1931).
The Minas Gerais meteorite has been known since 1888. It was found without a tag among the pieces in the collection of the National Museum and is believed to have been brought from the state of Minas Gerais. Source: Gomes & Keil (1980).
All information that does not have a specific source was extracted from the Meteoritical Bulletin Database.
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