Patos de Minas (octahedrite)                    18°35'S, 46°32'W

Patos de Minas, Minas Gerais state, Brazil

Find: 1925; main mass in 2002

Iron (IAB complex)

History: A small (18.4 g) end piece of a badly oxidized octahedrite was found in 1925 at the collection of the Escola de Minas Ouro Preto. In 1960 it was donated to Museu Nacional of Rio de Janeiro. The meteorite was mentioned in the British Museum catalog and the Handbook of iron meteorites of Buchwald, when it was named Patos de Minas (octahedrite), or Patos II, to distinguish it from Corrego do Areado, or Patos de Minas (hexahedrite). In 2002, a mass of about 200 kg was found by Paulo Garcia when plowing the land with a tractor.

Physical characteristics: One mass of about 200 kg has average dimensions of 54 × 33 × 22 cm. It is rough, elongated and very weathered, exhibiting some grooves due to terrestrial corrosion and with no signs of fusion crust.
Description: Polished sections display a poor medium Widmanstätten structure of irregular kamacite lamellae 1.1 ± 0.2 mm (max. 2.4 mm), with the Widmanstätten pattern not very obvious. Aspect ratios (length/width) of individual lamellae range from 1 to 8, most being 4-6. Terrestrial corrosion penetrates to a depth of 5 cm. Troilite nodules are very common. The structure is identical to Patos de Minas (octahedrite) so the two masses are considered to be paired.

Geochemistry: (John T. Wasson, UCLA, data obtained by INAA). Bulk composition: Co = 4.8, Ni = 83 (both mg/g); Ga = 67, Cu = 240, As = 15.4, Ir = 1.3 and Au = 1.7 (all in µg/g).

Classification: Iron (IAB complex); very weathered

Type specimens: A total of 1200 g of sample is on deposit at MNRJ/UFRJ/Rio de Janeiro, Brazil. The main mass was recently sold by the finder.

Submitted by: M. Zucolotto.