Uberaba meteorite, Uberaba, Minas Gerais, Brazili

Regional Level Types
Uberaba meteorite	Meteorite Fall Location
Uberaba	Municipality
Minas Gerais	State
Brazil	Country

Ordinary chondrite, veined (H5)
Fall, 29 June 1903; 40 kg

After a bolide was seen to move from NE to SW, detonations were heard and a large stone was seen to fall. Portions of the stone were apparently destroyed by the local population, but several kilograms were recovered and partially distributed. Prominent spherical and elongated, often polysomatic, chondrules of different textures range in apparent diameters from 0.2-1.1 mm [mean, 0.5 mm]. The fine-grained matrix is dominated by microcrystalline material. Olivine, low-Ca orthopyroxene, and Fe-Ni metal (kamacite, taenite) are the dominant mineralogical constituents. Minor amounts of albitic plagioclase and troilite are also present as well as very small ('accessory') amounts of diopside and chromite. Textures, total iron (Fe ~26 wt%), and the uniform olivine and pyroxene composition (Fa19.5, Fs17, resp.) are characteristics of the H5 chondrites (high iron group, relatively well equilibrated type). Shock veins are the most obvious indicators of moderately significant level S3 shocks. Terrestrial weathering has been largely confined to hydrous iron oxides which occasionally rim Fe-Ni metal.

A cosmic ray exposure (CRE) age of 3.9 Ma was reported by Graf and Marti (1995). However, perhaps more interesting is the fact that refinements of CRE age determinations using multiple isotope chronometers are leading to the first crude subgroupings of individual H meteorites such as Uberaba into cohorts that are likely products of specific impact events involving potentially identifiable earth-crossing asteroids (See references below).

Of Statistical and/or Local interest:

The H (relatively high in total iron) chondrites are the 2nd largest group of ordinary chondrites [ > 35% of well-classified, witnessed falls]. Nearly half of them belong to the H5 petrologic type subgroup. As of June 2016 Uberaba is the 18th most massive of the 172 meteorite falls classified exactly as H5 chondrites — and is the most massive of the four Brazilian H5 falls. Recovered masses from the other Brazilian H5 falls — Iguaracu, Itapicuru-Mirim, Macau — are much more modest, m ≤ 2kg). As of 2000 the largest relatively intact Uberaba specimen (~3.5 kg) was with the Escuola de Minas in Ouro Preto. Smaller masses have been held for several deades at the Museum National d'Histoire Naturelle in Paris (~1.1 kg) and the Naturhistorisches Museum in Wiens (~400 g).

Nota bene: There is some uncertainty about the precise date of fall. The date here is from Gomes & Keil (1980).

References

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