Augusto Pestana        28° 31’S, 53° 57’ W

Rio Grande do Sul, Brazil

Find: 1977 Oct

Classification: Iron meteorite (IIIE)

History: (Andre L. R. Moutinho) The meteorite was found by a farmer while cleaning a recently acquired property around Oct. 17, 1977. He noticed a very heavy rock when compared to others with similar size. The meteorite was stored for about 44 years and in 2021 a sample was sent to Andre L R Moutinho that confirmed the sample as a meteorite.

Physical characteristics: Elongated shape, 28 kg, 33 × 22 × 16 cm

Petrography: (A.L.R. Moutinho) The meteorites has suffered weathering and no fuscion crust was observed A polished etch slice measuring 50 × 30 mm was studied. The slice shows a typical coarse octahedrite widmanstaetten structure showing swollen kamacite lamellae with bandwidth of 1.82±0.34 mm (n=43). The kamacite lamellae are bordered by taenite and plessite fields that covers 40% of the slice area. Plessite fields are found in many forms as comb, acicular, martensitic and spheroidal. Schreibersite is found as rabhdite needles and as irregular forms. Troilite was not observed in the studied slice. (M. Pereira and F. Genezini/IPEN) Neutron Tomography: kamacite lamellae with bandwidth of 1.4±0.4 mm (n=112).

Geochemistry: North Chile (Filomena) as standard (C. Herd and P. Hill, UAb); ICP-MS method: Ni = 70, Co = 5.8 (both mg/g); Ir = 0.23, Ga = 17, Ge = 41, As = 30, Pt = 1.6, Cu = 168, Sb = 0.21, Pd = 3.8 (all ug/g). (M. S. Navarro and J. Enzweller, DGRN/Unicamp) LA-ICP-MS data: Co = 5.24 (mg/g); Cr = 18.6, Ir = 0.11, Ga = 21.5, Ge = 30.5, As = 24.5, Pt = 0.87, Cu = 183.1, Au = 2.07, W = 0.24, Pd = 5.01, Ag = 0.16, (all ug/g). (R. Scholz and G. N. Queiroga, DEGEO/EM/UFOP). EPMA: kamacite: 6.60% Ni, 0.58% Co.

Classification: Iron, IIIE, based on the coarse octahedrite texture and the composition, following Wasson et al. (1998)). Although the composition is close to IIIAB group, with relatively high Au, the bandwidth indicates IIIE. Aletai (IIIE) also has a similar Au content of 1.86 µg/g.

Specimens: Main mass with finder, 21.5 g at Unicamp, 46.2 g with Andre L R Moutinho,