VARRE-SAI

Iron

TIPO:

CLASSE:

CLAN:

GRUPO:

SUB-GRUPO:

TIPO PET.:

EST. CHOQUE:

INTERPERISMO:

PAÍS:

ANO:

DESCRIÇÃO:

CHONDRITE

ORDINARY

H-L-LL

L

5

S4

W0

BRAZIL - RJ

2010

Equilibrated Ordinary hondrite L5, Shock Stage S4 and Weathering W0.

PETROGRAFIA:

The chondrules and the fragments of the chondrules are observed in a recrystallized matrix cut by thin dark veins. Mineralogically dominated by olivine, pyroxene, plagioclase, sulfides and FeNi metal. Olivine shows wave extinction and mosaicism. Larger grains show fractures and PDFs. Pyroxenes, especially orthopyroxene, exhibit a texture similar to that of olivine. Plagioclase typically at 50 μm, some showing wave extinction, while some are twinned. Troilite and FeNi metal occur as irregularly shaped grains. The conduits vary in size from 0.3 to 5 mm, with an average size of ~ 0.8 mm. Clearly discernible are the RP (~ 1.9 mm) and BO (~ 2.2 mm) conduits.

GEOQUÍMICA:

Chaves et al. (2011) identified forsteritic olivine (Fo76Fa24) and enstatitic orthopyroxene (Wo1En79Fs20). Clinopyroxene shows composition affinity with augite (Wo44En48Fs08) and plagioclase with oligoclase (Ab84An11Fs08). In reflected light, the opaque assembly is composed of troilite, FeNi alloys (kamacite, taenite, tetrataenite) and chromite. Using transmitted light, essentially the mineralogy is 38% olivine, 31% orthopyroxene, 18% plagioclase, 11% opaque minerals and 2% clinopyroxene. The accessory set is entirely composed of opaque minerals. Source: Rangel et al. (2017).

CLASSIFICAÇÃO:

The XRD results indicate that the chondrite network parameters are pyroxene with low calcium content (enstatite) and olivine rich in Mg (forsterite). Petrographic analysis also indicates the presence of plagioclase. This compositional assembly proves that Varre-Sai is a equilibrated stony, consistent with the type 5 petrological group of Van Schmus and Wood (1967), thus confirming the work of Chaves et al. (2011) and Zucolotto et al. (2012). Although Chaves et al. (2011) classified the meteorite as S5, evidence including wave extinction in olivines, planar fractures, mosaicism in olivine and shock veins defines Varre-Sai in shock stage S4, according to Stöffler et al. (1991), confirming the results of Zucolotto et al. (2012). Regarding the chemical composition, REEs and the main elements related to the main mineral phases of chondrites (Fe2O3, NiO, MgO, Al2O3, Ca2O and Na2O) show very strong similarities between Varre-Sai and other L chondrites. In Harker's diagrams, the Varre-Sai, L and LL chondrites form a single group, suggesting that there are no different significant chemicals. For more information about the meteorite, just access the following link: http://dx.doi.org/10.1080/00206814.2017.1308842. Source: Rangel et al. (2017).

CLASSIFICADORES:

M.E.Zucolotto, M.E.Varela and L.L.Antonello

HISTÓRIA:

Around 9:00 pm UT (about noon, local time) on June 19, 2010, a glowing fireball was observed on the East side of Brazil. Germano, who lives on the border of Rio de Janeiro and Espírito Santo, heard several explosions and saw two black objects falling. A rock ~ 600 g fell about 15m from him. Early the next day, he found another piece under a banana tree. The place of the fall belongs to the city of Varre-sai. The precise location is about 17 km from Varre-Sai (state of Rio de Janeiro) and 8 km from Guaçui (state of Espírito Santo). The first piece recovered was about 100 m inside the border of the state of Rio de Janeiro. Source: Rangel et al. (2017).

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