Conceicao do Tocantins        12°11’S, 47°16’W

Tocantins, Brazil

Find: 2020 Oct

Classification: Iron meteorite (IIAB)

History: (Gabriel Gonçalves, USP, and André L. R. Moutinho) The meteorite was found by a gold miner on a farm in the rural area of Conceição do Tocantins, state of Tocantins, when looking for gold with a metal detector in October 2020. The meteorite was buried at a depth of approximately 30 cm. The gold prospector’s sister-in-law posted pictures of the "stone" on social media page and was first noticed by Gabriel Gonçalves. Sample was sent to A.L.R. Moutinho who confirmed it as a meteorite.

Physical characteristics: A regular weatheread mass weighing 449 g and measuring ~79 × 52 × 32 mm

Petrography: (Andre L. R. Moutinho) The meteorites has suffered weathering and no fusion crust was observed. A polished etched slice measuring 56 × 32 mm shows a structureless surface typical of hexahedrites with numerous plate-shaped and prismatic rhabdites. Many rhabdites are surrounded by oxide. Schreibersite is also found around troilite nodules. Kamacite shows shock twinning features known as Neumann lines. A troilite nodule inclusion (5 × 2 mm) was observed. A heat zone region was observed on one side of the slice.

Geochemistry: ICP-MS data, using a sample of North Chile (Filomena) as standard (Chris Herd and Patrick Hill, UAb) ICP-MS method: Ni = 53.8, Co = 4.5 (both mg/g); Cr = 129, Ir = 6.12, Ga = 57.21, Ge = 148.3, As = 5.33, Pt = 26.6, Cu = 137.11, W = 2.603, Pd = 0.55, Ag = 0.002, (all µg/g). (Margareth. S. Navarro, Jacinta Enzweller, and Alvaro P. Crósta, DGRN/UNICAMP). LA-ICP-MS method: Ni = 54.58, Co = 4.40 (both mg/g); Cr = 37, Ir = 7.5, Ga = 62, Ge = 147, As = 2.5, Pt = 25.4, Cu = 156, Au = 0.50, W = 3.0, Pd = 1.6, Ag = 0.10, Os = 2.4 (all µg/g). (Ricardo Scholz and Gláucia N. Queiroga, DEGEO/EM/UFOP). EPMA: kamacite 5.65 % Ni, 0.46 % Co.

Classification: Iron, IIAB. Similar to Arraias but resolvable based on Ir and Os content. Type is consistent with the analysed structure.

Specimens: Main mass with A.L.R. Moutinho, 21.6 g at UNICAMP