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Northwest Africa 2635
Basic information Name: Northwest Africa 2635
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 2635
Observed fall: No
Year found: 2004
Country: (Northwest Africa)
Mass:help 4.2 kg
Meteoritical Bulletin:  MB 89  (2005)  Achondrite-ung
MetBase:  v. 7.1  (2006)  Achondrite-ung
Recommended:  Achondrite-ung    [explanation]

This is 1 of 157 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Writeup from MB 89:

Northwest Africa 2635

Northwest Africa

Purchased October 2004

Achondrite (ungrouped)

A 4.2 kg, partially crusted stone was purchased in Erfoud, Morocco. Description and classification (T. Bunch and J. Wittke, NAU), results from one thin section (2.4 cm2): mostly recrystallized into fine-grained (<0.5 mm, avg. = 0.185 mm) polygonal and subhedral grains with the exception of several medium to large (1.2–3.0 mm) orthopyroxene grains that contain very small olivine (<0.1 mm) inclusions. Olivine and orthopyroxene analyses are homogeneous within the precision of the electron microprobe (± 0.15 mol %) and indicate H chondrite affinities. Olivine, Fa18.9 (FeO/MnO = 38.1); orthopyroxene, Fs16.8Wo2.9 (FeO/MnO = 20.0); plagioclase, An15.1Or4.7; metal (only taenite found), Ni = 18.9 wt. %; chromite (only one grain found), cr# = 84.5; FeS, Ni = 1.42 wt. % and Co = 0.28 wt. %, minor merrillite. Most metal has been oxidized; specimen contains ~70% olivine implying it contained less metallic iron than an H chondrite when fresh. Oxygen isotope replicate analyses (D. Rumble, CIW) of acid washed, bulk sample by lased fluorination gave δ17O = 3.23 and 2.98, δ18O = 5.03 and 4.37 and Δ17O = 0.614 and 0.708. Weathering grade, W4 with staining; shock level, low. Specimens: type sample, 23.2 g, NAU*; main mass, Strope/MFarmer

Data from:
  Table 0
  Line 0:
Classifier:T. Bunch, NAU
Type spec location:NAU* type specimen now at UWB. One polished thin section and one epoxy mount at UWB.
Comments:Work name 550, thin section QJE4
Data from:
  Table 7
  Line 348:
Mass (g):4,200
Classifier:Ted Bunch, NAU
Type spec mass (g):23.2
Type spec location:NAU*
Plots: O isotopes:  
   and collections
NAU*: Collection discontinued. Specimens redistributed as shown in individual meteorite records, United States (institutional address; updated 24 Jun 2024)
UWB: University of Washington, Burke Museum of Natural History and Culture, Box 353010 Seattle, WA 98195, United States (institutional address; updated 9 Oct 2023)
CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address)
MFarmer: Michael Farmer, P.O. Box 86059, Tucson, AZ 85754-6059, United States; Website (private address)
Strope: 421 Fourth Street, Glen Dale, WV 26038, United States; Website (private address)
NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States (institutional address; updated 12 Apr 2012)
References: Published in Meteoritical Bulletin, no. 89, MAPS 40, A201-A263 (2005)
Published in Meteoritical Bulletin, no. 113, in preparation (2024)
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Photos from the Encyclopedia of Meteorites:
Mike Farmer      
Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Gerald Armstrong   

     This is 1 of 9825 approved meteorites from (Northwest Africa) (plus 1851 unapproved names)

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