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Conceicao do Tocantins
Basic information Name: Conceicao do Tocantins
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: No
Year found: 2021
Country: Brazil
Mass:help 449 g
Recommended:  Iron, IIAB    [explanation]

This is 1 of 150 approved meteorites classified as Iron, IIAB.   [show all]
Search for other: IIAB irons, Iron meteorites, and Metal-rich meteorites
Comments: Approved 29 Jan 2022
Writeup from MB 111:

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

Data from:
  Table 0
  Line 0:
Origin or pseudonym:field
Date:2020 Oct
Mass (g):449
Class:Iron, IIAB
Classifier:C. Herd and P. Hill, Uab. A. P. Crosta, Unicamp. G. Gonçalves, USP and A. L. R. Moutinho
Type spec mass (g):21.6
Type spec location:UNICAMP
Main mass:Andre L R Moutinho
Finder:L.M. Souza
Comments:Submitted by A.P. Crosta, G. Gonlçaves and A.L.R. Moutinho
   and collections
UAb: 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB, T6G 2E3, Canada, Canada; Website (institutional address; updated 17 Oct 2011)
USP: Museu de Geociências - USP Rua do Lago, 562 CEP: 05508-080 Butantã - SP Brazil, Brazil; Website (institutional address; updated 22 Oct 2022)
UNICAMP: Institute of Geosciences Minerals Collection Rua Carlos Gomes 250 Cidade Universitária Zeferino Vaz Campinas, SP 13083-855, Brazil; Website (institutional address; updated 17 Dec 2021)
References: Published in Meteoritical Bulletin, no. 111, in preparation (2022)
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Public domain photographs:
Alvaro P. Crosta         

     Recommended::   (12° 11'S, 47° 16'W)

     This is 1 of 2 approved meteorites from Tocantins, Brazil (plus 1 impact crater)
     This is 1 of 87 approved meteorites from Brazil (plus 6 unapproved names) (plus 7 impact craters)
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