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Northwest Africa 7605
Basic information Name: Northwest Africa 7605
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 7605
Observed fall: No
Year found: 2012
Country: (Northwest Africa)
Mass:help 320 g
Meteoritical Bulletin:  MB 102  (2013)  Brachinite
Recommended:  Brachinite    [explanation]

This is 1 of 59 approved meteorites classified as Brachinite.   [show all]
Search for other: Brachinites, Primitive achondrites
Comments: Approved 1 Jan 2013
Writeup from MB 102:

Northwest Africa 7605 (NWA 7605)

Northwest Africa

Purchased: 2012

Classification: Primitive achondrite (Brachinite)

History: Purchased by Stefan Ralew in 2012 from a dealer in Erfoud, Morocco.

Physical characteristics: Dark brown, rounded stone with small areas of remnant fusion crust. Interior slices show the rock to be composed of black, interlocking elongate grains with a preferred orientation, plus elongate, lighter gray-colored oikocrysts (up to 15 mm by 5 mm in size).

Petrography: (A. Irving and S. Kuehner, UWS) Composed mostly of olivine with subordinate clinopyroxene, Ti-V-bearing chromite, pyrrhotite and rare kamacite, plus large oikocrysts of orthopyroxene + clinopyroxene enclosing ovoid olivine chadacrysts. All mafic silicates exhibit a strongly-oriented grain shape fabric. Intergrowths of pure iron metal + orthopyroxene are present along olivine grain boundaries and along microfractures within olivine grains.

Geochemistry: Olivine (Fa26.1-26.2, FeO/MnO = 43-49; chadacrysts in pyroxene Fa24.8-24.9, FeO/MnO = 43-52), orthopyroxene (oikocryst Fs25.8Wo2.5, FeO/MnO = 39, Cr2O3 = 0.2 wt.%; with metal on olivine margins Fs21.8-21.9Wo1.0-2.1, FeO/MnO = 28-30), clinopyroxene (Fs10.2-10.6Wo44.0-47.8, FeO/MnO = 23-31, Al2O3 = 0.7-0.8 wt.%; Cr2O3 = 0.7-0.9.%; oikocryst Fs10.2Wo43.6, FeO/MnO = 32, Al2O3 = 0.7 wt.%, Cr2O3 = 0.7 wt.%). Oxygen isotopes (K. Ziegler, UNM): analysis of an acid-washed sample by laser fluorination gave δ17O = 2.370; δ18O = 4.822; Δ17O = -0.176 per mil.

Classification: Brachinite. The mineralogy and oxygen isotopic composition of this specimen are similar to those of other brachinites, but the oriented grain fabric and large pyroxene oikocrysts are unusual.

Specimens: A total of 20 g of material and one polished thin section are on deposit at UWB. The main mass is held by Ralew.

Data from:
  Table 0
  Line 0:
Place of purchase:Erfoud
Date:P 2012
Mass (g):320
Shock stage:low
Weathering grade:low
Fayalite (mol%):24.8-26.2
Ferrosilite (mol%):25.8; 10.2-10.6
Wollastonite (mol%):2.5; 43.6-47.8
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):20
Type spec location:UWB
Main mass:S. Ralew
Comments:RA12-106; 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)
UWB: University of Washington, Burke Museum of Natural History and Culture, Box 353010 Seattle, WA 98195, United States (institutional address; updated 9 Oct 2023)
Ralew: Stefan Ralew, Kunibertstraße 29, 12524 Berlin, Germany; Website (private address)
References: Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015
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     This is 1 of 9559 approved meteorites from (Northwest Africa) (plus 1872 unapproved names)

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