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Castanheiras
Basic information Name: Castanheiras
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: No
Year found: 2017
Country: Brazil
Mass:help 1162 g
Classification
  history:
Recommended:  Iron, ungrouped    [explanation]

This is 1 of 143 approved meteorites (plus 1 unapproved name) classified as Iron, ungrouped.   [show all]
Search for other: Iron meteorites, Metal-rich meteorites, and Ungrouped irons
Comments: Approved 11 Dec 2021
Writeuphelp
Writeup from MB 110:

Castanheiras        11°29’11’’S, 61°48’41’’W

Rondonia, Brazil

Find: 2017 Oct 15

Classification: Iron meteorite (ungrouped)

History: The meteorite was found in the afternoon of October 15, 2017, on a rural property in the municipality of Castanheira, Rondônia, Brazil, by the farmer Ademilson Vieira da Luz, while he was plowing the land for the end of year planting. He discovered the iron mass when the tractor passed over a resistance, causing a different noise than when the plow cuts through the soil. He stopped the machine to see what had happened and identified a black mass about 20 cm long with a density much higher than any other stone he had ever seen. Almost a year later, in September 2018, the mass was presented to geologist Paulo Afonso Ribeiro Barbosa, an Exploration Manager who was developing a research project in the finding area. Due to its high density and apparent nickel content, measured by a portable X-ray spectrometer, it was quickly assumed that the mass could be an iron meteorite and Prof. César Ferreira Filho at the University of Brasilia was contacted to liaise with a specialist to obtain a scientific classification of the material. After some negotiations, the finder of the mass, Mr. Ademilson, finally agreed to donate the entire material to the Geological Museum, University of Brasilia, Brazil. In 2020, a small sample of the iron was send to Dr. Ansgar Greshake at the MNB for classification.

Physical characteristics: Individual with black to brownish regmaglypted exterior.

Petrography: Etching of a polished section reveals a hexaedrite texture with several sets of Neumann lines and abundant rhabdites. Terrestrial alteration occurs along fractures.

Geochemistry: µXRF data (MNB): Ni = 4.68 wt%. ICP-MS data (H. Pourkhorsandi and V. Debaille, ULB): Ni = 4.78, Co = 0.37, P = 0.18 (all wt%); Cr = 64.1, Cu = 84.5, Ge = 100.7, Ga = 39.1, As = 2.67, Mo = 4.06, Pd = 1.31, Sb = 0.03, W = 2.03, Ir = 15.0, Au = 0.28 (all ppm)

Classification: Iron meteorite, ungrouped. The meteorite shows a hexahedrite structure with Neumann bands. IIG can be excluded based on the Ge/Ga ratio and high Ir concentration. Elemental concentrations also do not fit the IIAB trends (Wasson et al., 2007)

Bibliography:
  • Wasson J.T., Huber H., and Malvin D.J. (2007) Formation of IIAB iron meteorites. Geochim. Cosmochim. Acta 71, 760-781 (link)
Data from:
  MB110
  Table 0
  Line 0:
State/Prov/County:Rondonia
Date:2017 Oct 15
Latitude:11°29'11''S
Longitude:61°48'41''W
Mass (g):1162
Pieces:1
Class:Iron, ungrouped
Weathering grade:moderate
Classifier:A. Greshake, MNB
Type spec mass (g):25
Type spec location:MNB
Main mass:Museu de Geociencias da Universidade de Brasi­lia, Instituto de Geociencias - ICC Centro - Universidade de Brasi­lia, 70910900 Brasi­lia, DF, Brazil
Finder:Ademilson Vieira da Luz
Comments:Submitted by Ansgar Greshake
Institutions
   and collections
MNB: Museum für Naturkunde, Invalidenstraße 43, D-10115 Berlin, Germany (institutional address; updated 24 Dec 2011)
ULB: Université libre de Bruxelles Avenue Franklin Roosevelt 50 - 1050 Bruxelles, Belgium (institutional address; updated 27 Sep 2018)
Catalogs:
References: Published in Gattacceca J., McCubbin F.M., Grossman J., Bouvier A., Chabot N.L., D'Orazio M., Goodrich C., Greshake A., Gross J., Komatsu M., Miao B., and Schrader D. (2022) The Meteoritical Bulletin, No. 110. Meteorit. Planet. Sci. 1-4
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Geography:

Brazil
Coordinates:
     Recommended::   (11° 29' 11"S, 61° 48' 41"W)

Statistics:
     This is the only approved meteorite from Rondonia, Brazil
     This is 1 of 87 approved meteorites from Brazil (plus 6 unapproved names) (plus 7 impact craters)
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