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Northwest Africa 7635
Basic information Name: Northwest Africa 7635
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 7635
Observed fall: No
Year found: 2012
Country: (Northwest Africa)
Mass:help 195.8 g
Meteoritical Bulletin:  MB 102  (2013)  Martian (shergottite)
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 318 approved meteorites (plus 2 unapproved names) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Comments: Approved 6 May 2013
Writeup from MB 102:

Northwest Africa 7635 (NWA 7635)

(Northwest Africa)

Purchased: 2012 May

Classification: Martian meteorite (Shergottite)

History: Purchased near Dakhla, Morocco in May 2012 by Ali and Mohammed Hmani.

Physical characteristics: A single black, partly fusion crusted stone (195.8 g), containing prominent lath-shaped, glassy maskelynite phenocrysts (some in clusters) in a fine-grained black matrix.

Petrography: (A. Irving and S. Kuehner, UWS) Porphyritic texture. Phenocrysts of intermediate plagioclase (as blocky laths, some in groups, completely converted to maskelynite), ferroan olivine, subcalcic augite and Ti-free magnetite are set in a much finer grained, quenched matrix dominated by clinopyroxene (zoned from augite to ferropigeonite) in parallel growth with plagioclase. Accessory pyrrhotite and rare ilmenite are present. No phosphates were found.

Geochemistry: Olivine (Fa60.5-60.6; FeO/MnO = 43-49), subcalcic augite (Fs28.5Wo32.3; FeO/MnO = 38; TiO2 = 0.20 wt.%; Cr2O3 = 0.93 wt.%), ferropigeonite Fs60.6-77.2Wo17.6-21.8; FeO/MnO = 41-48). Bulk composition (G. Chen, UAb): Analysis by ICP-MS of powder ground in agate from a 1.1 g interior slice gave (in ppm) Ni 7.7, Rb 0.40, Sr 69.2, Zr 9.8, Ba 9.9, La 0.19, Ce 0.83, Nd 1.38, Sm 0.85, Eu 0.33, Gd 1.65, Yb 1.99, Lu 0.30. Oxygen isotopes (K. Ziegler, UNM): three acid washed subsamples analyzed by laser fluorination gave, respectively (all per mil), δ17O = 2.536, 2.521, 2.513; δ18O = 4.241, 4.220, 4.217; Δ17O = 0.297, 0.294, 0.287 (for a TFL slope of 0.528).

Classification: Martian (shergottite, olivine-plagioclase-phyric). This specimen is distinct from other shergottites in containing phenocrysts of very ferroan olivine and maskelynite.

Specimens: 21.2 g of material and 2 polished thin sections are on deposit at UWB. The main mass was held by Hmani  and subsequently was sold to an anonymous collector.

Data from:
  Table 0
  Line 0:
Place of purchase:Dakhla
Date:P 2012 May
Mass (g):195.8
Class:Martian (shergottite)
Shock stage:moderate
Weathering grade:low
Fayalite (mol%):60.5-60.6
Ferrosilite (mol%):28.5; 60.6-77.2
Wollastonite (mol%):32.3; 17.6-21.8
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):21.1
Type spec location:UWB
Main mass:Anonymous
Comments:OT01; submitted by A. Irving
Plots: O isotopes:  
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
UAb: 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB, T6G 2E3, Canada, Canada; Website (institutional address; updated 17 Oct 2011)
UWB: University of Washington, Burke Museum of Natural History and Culture, Box 353010 Seattle, WA 98195, United States (institutional address; updated 9 Oct 2023)
Hmani: A. Hmani Moroccan Imports, 13 rue Jules Hardouin Mansart, 92600 Asnières, France (private address)
References: Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015
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     This is 1 of 9570 approved meteorites from (Northwest Africa) (plus 1871 unapproved names)

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