|Northwest Africa 4882|
|Basic information||Name: Northwest Africa 4882|
This is an OFFICIAL meteorite name.
Abbreviation: NWA 4882
Observed fall: No
Year found: 2007
Mass: 3.1 kg
This is 1 of 41 approved meteorites classified as Brachinite. [show all]
Search for other: Brachinites, Primitive achondrites
Approved 30 Jan 2008|
Revised 17 Dec 2008: added erratum from mb94; 2008-08-04 final writeup
Writeup from MB 93:
Northwest Africa 4882
Find: July 2007
History: Purchased by Greg Hupé in July 2007 from a dealer in Tagounite, Morocco.
Physical characteristics: Two dense, dark brown, broken rounded stones (2891 g and 206 g) with weathered fusion crust on some original exterior surfaces and thin desert varnish coatings on hackly broken surfaces.
Petrography: (A. Irving and S. Kuehner, UWS) Coarse-grained rock (mostly 0.2-0.8 mm) with protogranular texture, composed predominantly of olivine with subordinate green, Cr-bearing diopside, K-poor plagioclase, chromite, iron sulfide, and kamacite (partially altered to iron hydroxides). Plagioclase is interstitial to mafic silicates and is heterogeneous in distribution. Very fine-grained (2-10 µm), polyphase assemblages composed mostly of orthopyroxene, Ni-bearing pyrrhotite and Ni-free metal with variable amounts of fayalite and chromite occur around larger pyrrhotite grains within olivine, and also as small, isolated apparent inclusions within olivine.
Geochemistry: Olivine (Fa35.0-35.2, FeO/MnO = 70.9-71.3), clinopyroxene (Fs9.3Wo47.1, FeO/MnO = 38.6, Cr2O3 = 0.76wt%, Al2O3 = 1.05 wt%), plagioclase (An32.1- 37.6Or0.3-0.5), chromite [Cr/(Cr + Al) = 0.717, Mg/(Mg + Fe) = 0.239, TiO2 = 0.71 wt%, ZnO = 0.30 wt%]. Oxygen isotopes: (D. Rumble, CIW) Replicate analyses of acid-washed silicate material by laser fluorination gave, respectively, δ18O = 2.064, 2.095; δ17O = 4.368, 4.455; Δ17O = -0.234, -0.248 per mil.
Classification: Achondrite (brachinite). This specimen is very similar in external appearance, texture, and mineral compositions to NWA 4969, with which it may be paired (Wittke et al. 2008). It also is very similar to NWA 3151 in texture, olivine, and plagioclase compositions, and patterns of staining around metal (Irving et al. 2005). However, the clinopyroxenes in these two specimens have somewhat different compositions, and NWA 3151 contains much less plagioclase and lacks the distinctive polyphase assemblages found in NWA 4882. Specimens: A total of 20.4 g of sample and one polished thin section are on deposit at UWS. GHupé holds the main mass.
Submitted by: A. Irving, UWS.
Writeup from MB 94:
Correction: δ17O = 2.095, 2.064; δ18O = 4.455, 4.368; Δ17O = -0.248,-0.234 (all ‰).
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address)
GHupé: Gregory M. Hupé, 9003 Placid Lakes Blvd., Lake Placid, FL 33852, United States; Website (private address)
|References:||Published in Meteoritical Bulletin, no. 93, MAPS 43, 571-632 (2008)|
Published in Meteoritical Bulletin, no. 94, MAPS 43, 1551-1588 (2008)
This is 1 of 728 approved meteorites from Algeria (plus 26 unapproved names) (plus 4 impact craters)
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