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Northwest Africa 7835
Basic information Name: Northwest Africa 7835
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 7835
Observed fall: No
Year found: 2013
Country: (Northwest Africa)
Mass:help 56 g
Meteoritical Bulletin:  MB 103  (2014)  Achondrite-ung
Recommended:  Achondrite-ung    [explanation]

This is 1 of 101 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 21 Jun 2014
Writeup from MB 103:

Northwest Africa 7835 (NWA 7835)

(Northwest Africa)

Purchased: 2013 Nov

Classification: Ungrouped achondrite

History: Purchased by S. Ralew in November 2013 from a dealer in Zagora, Morocco.

Physical characteristics: A very fresh stone (56 g) coated in black, glossy fusion crust, which upon cutting was seen to be composed mostly of gray pyroxene and pale yellow olivine with very little metal or sulfide.

Petrography: (A. Irving and S. Kuehner, UWS) This specimen is composed predominantly of large grains (up to 6 mm) of olivine and compositionally-zoned orthopyroxene with minor clinopyroxene, chromite, rare taenite and troilite in a sparse, interstitial matrix of vesicular, feldspathic glass charged with angular fragments of the constituent minerals. No chondrules are present.

Geochemistry: Olivine (Fa23.7-24.6; FeO/MnO = 57-60, N = 4), orthopyroxene (Fs19.5-20.4Wo1.4-1.6; more magnesian cores Fs15.0-15.8Wo0.8-0.7; FeO/MnO = 33-37), clinopyroxene (Fs7.2Wo45.0; FeO/MnO = 24). Oxygen isotopes (K. Ziegler, UNM): analyses of random multiple subsamples of the specimen (after acid washing) by laser fluorination gave (all in per mil) δ17O = 3.190, 1.971, 2.309, 1.889, δ18O = 5.042, 3.709, 4.044, 3.870, Δ17O = 0.528, 0.013, 0.174, -0.154 (for a TFL slope of 0.528). Bulk composition (R. Conrey, WSU; G. Chen, UAb): analyses of representative, clean bulk cutting dust by X-ray fuorescence spectrometry and ICPMS gave (in wt.%) SiO2 = 42.9, TiO2 = 0.16, Al2O3 = 2.6, Cr2O3 = 0.45, FeO = 17.9, MnO = 0.33, MgO = 29.9, CaO = 1.7, Na2O = 0.85, K2O = 0.13, P2O5 = 0.05; (in ppm) La = 0.45, Ce = 1.23, Nd = 0.89, Sm = 0.28, Eu = 0.10, Gd = 0.37 Dy = 0.39, Er = 0.24, Yb = 0.23, Lu = 0.04, Hf = 0.31.

Classification: Ungrouped achondrite. This unusual specimen appears to have some affinities to ordinary chondrites, yet chondrules are absent and there is hardly any metal present (and no kamacite). The bulk major and trace elements are broadly chondritic, yet only one out of four subsamples analyzed for oxygen isotopes plots near the trends for any typical ordinary chondrites (namely H chondrites). However, the compositions of the mafic minerals are inconsistent with those of H chondrites and more similar to those of L chondrites. Three other oxygen isotope analyses conducted on acid-washed subsamples of this very fresh specimen plot close to the TFL. The overall texture is that of a melt-matrix fragmental breccia, which could explain the range of Δ17O values, although no foreign clasts were observed in the polished section.

Specimens: 11.9 g and one large polished thin section are at UWB. The remaining material is held by Ralew.

Data from:
  Table 0
  Line 0:
Place of purchase:Zagora
Date:P 2013 Nov
Mass (g):56
Shock stage:low
Weathering grade:low
Fayalite (mol%):23.7-24.6
Ferrosilite (mol%):19.5-20.4
Wollastonite (mol%):1.4-1.6
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):11.9
Type spec location:UWB
Main mass:S. Ralew
Comments:See accompanying photo documentation.; 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, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
Ralew: Stefan Ralew, Kunibertstraße 29, 12524 Berlin, Germany; Website (private address)
WSU: Washington State University Pullman, WA 99164-2812, United States (institutional address)
References: Published in Meteoritical Bulletin, no. 103, MAPS 52, 1014, May 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12888/full
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Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Solar Anamnesis         

     This is 1 of 7655 approved meteorites from (Northwest Africa) (plus 1972 unapproved names)

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