The Palmas de Monte Alto meteorite: mineral chemistry and petrographic features

Authors

  • Wilton Pinto Carvalho Universidade Federal da Bahia. Programa de Pós-Graduação em Geologia
  • Débora Correia Rios Universidade Federal da Bahia. Programa de Pós-Graduação em Geologia
  • Maria Elizabeth Zucolotto Universidade Federal do Rio de Janeiro. Museu Nacional
  • Herbet Conceição Universidade Federal de Sergipe. Programa de Pós Graduação em Geociências e Análise de Bacias
  • Acácio José Silva Araújo Universidade Federal da Bahia. Programa de Pós-Graduação em Geologia
  • Amanda Araújo Tosi Universidade Federal do Rio de Janeiro. Instituto de Geociências. Labsonda

DOI:

https://doi.org/10.11606/issn.2316-9095.v18-132539

Keywords:

Meteorite, Iron, Nickel, Palmas de Monte Alto

Abstract

Several parameters have been used to classify iron meteorites, mainly mineralogy and chemical and structural properties. This paper presents these classificatory parameters, allowing a more detailed view to enlarge knowledge about the Palmas de Monte Alto meteorite. This siderite was found on the top of Monte Alto ridge, before 1955, being one of the six specimens that compose the Bahia State meteorite collection. It consists of a single mass of 97 kg which shows a highstage of oxidation in places where the crust has been removed. Its mineralogy includes kamacite, taenite, plessite, as well as secondary mineral phases such the Fe-Ni oxide akaganeite. There are also accessory minerals of common occurrence in Fe-Ni alloys of spatial origin like schreibersite, chromite and troilite, and a rare solid solution of Fe-Mn orthophosphates composed by the minerals heterosite-purpurite or sarcopside-graftonite as extreme members. The average width of its bands of kamacita (0.95 ± 0.15 mm) allows classifying it structurally as a medium octahedrite, with a medium and well-defined Windmasttaten pattern. Its contents of Ni (9.40 wt %) and Co (0.46 wt %) — compared to trace-elements Ga (22 ppm), Ir (0.70 ppm), As (16.00 ppm) and Au (1.70 ppm) — recommend the inclusion of this meteorite in the chemical group IIIAB.

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Author Biographies

  • Wilton Pinto Carvalho, Universidade Federal da Bahia. Programa de Pós-Graduação em Geologia

    Instituto de Geociências, Grupo de Pesquisa Laboratório de Petrologia Aplicada à Pesquisa Mineral

  • Débora Correia Rios, Universidade Federal da Bahia. Programa de Pós-Graduação em Geologia

    Instituto de Geociências, Grupo de Pesquisa Laboratório de Petrologia Aplicada à Pesquisa Mineral

  • Maria Elizabeth Zucolotto, Universidade Federal do Rio de Janeiro. Museu Nacional

    Departamento de Geologia. Grupo de Pesquisa Laboratório de Petrologia Aplicada à Pesquisa Mineral

  • Herbet Conceição, Universidade Federal de Sergipe. Programa de Pós Graduação em Geociências e Análise de Bacias

    Programa de Pós Graduação em Geociências e Análise de Bacias

  • Acácio José Silva Araújo, Universidade Federal da Bahia. Programa de Pós-Graduação em Geologia

    Instituto de Geociências, Grupo de Pesquisa Laboratório de Petrologia Aplicada à Pesquisa Mineral

  • Amanda Araújo Tosi, Universidade Federal do Rio de Janeiro. Instituto de Geociências. Labsonda

    Instituto de Geociências. Labsonda. UFRJ

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Published

2018-10-03

Issue

Vol. 18 No. 3 (2018)

Section

Articles

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How to Cite

Carvalho, W. P., Rios, D. C., Zucolotto, M. E., Conceição, H., Araújo, A. J. S., & Tosi, A. A. (2018). The Palmas de Monte Alto meteorite: mineral chemistry and petrographic features. Geologia USP. Série Científica, 18(3), 15-31. https://doi.org/10.11606/issn.2316-9095.v18-132539