|Northwest Africa 4468|
|Basic information||Name: Northwest Africa 4468|
This is an OFFICIAL meteorite name.
Abbreviation: NWA 4468
Observed fall: No
Year found: 2006
Country: (Northwest Africa)
Mass: 675 g
This is 1 of 139 approved meteorites (plus 1 unapproved name) classified as Martian (shergottite). [show all]
Search for other: Martian meteorites
|Comments:||Approved 28 Mar 2007|
Writeup from MB 91:
Northwest Africa 4468
Find: Summer 2006
Achondrite (Martian, basaltic shergottite)
History: Found in the western part of the Sahara in summer 2006 and purchased in Laâyoune by G. Hupé in July 2006.
Petrography: (A. Irving and S. Kuehner, UWS) Large ovoid pyroxene oikocrysts (2–10 mm across) enclosing chadacrysts of Ti-poor chromite and olivine are set in an interstitial matrix of 35% olivine, 30% clinopyroxene, 25% maskelynite (all vol%), Ti-chromite, ilmenite, merrillite, Cl-apatite (as prisms up to 0.8 mm long), and pyrrhotite. Inclusions (up to 300 µm across) surrounded by radial shock relaxation fractures occur within matrix olivine grains; some are quenched melt inclusions and others consist mainly of maskelynite. The specimen is cross-cut by sporadic, thin, dark, glassy shock veins (Irving et al. 2007).
Mineral compositions and geochemistry: Pyroxene oikocrysts are zoned from orthopyroxene cores (Fs24.5Wo4.4; FeO/MnO = 35.4) with mantles of pigeonite (Fs26.3Wo6.3; FeO/MnO = 29.4) to augite rims (Fs17.9Wo33.6; FeO/MnO = 24.9). Olivine chadacrysts (as magnesian as Fa28.8) typically become progressively more ferroan from pyroxene core to rim (up to Fa39.9). Matrix olivine (Fa40.7; FeO/MnO = 50.2), matrix clinopyroxene (Fs31.3Wo8.1, Fs19.6Wo31.3), matrix maskelynite (An38.7–54Or3.9–2.3); maskelynite in inclusions within olivine is inhomogeneous and K-Na-rich (Or52.6Ab40.7An6.7).
Classification: Achondrite (Martian, basaltic shergottite).
Type specimen: A total of 20.2 g and one large 3.8 × 2.8 cm thin section are on deposit at UWS. G. Hupé holds the main mass.
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
|References:||Published in Meteoritical Bulletin, no. 91, MAPS 42, 413-466 (2007)|
This is 1 of 5256 approved meteorites from (Northwest Africa) (plus 2147 unapproved names)
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