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Northwest Africa 4826
Basic information Name: Northwest Africa 4826
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 4826
Observed fall: No
Year found: 2006
Country: (Northwest Africa)
Mass:help 344 g
Meteoritical Bulletin:  MB 94  (2008)  Howardite
Recommended:  Howardite    [explanation]

This is 1 of 398 approved meteorites classified as Howardite.   [show all]
Search for other: Achondrites, HED achondrites, and Howardites
Comments: Approved 17 Apr 2008
Writeup from MB 94:

Northwest Africa 4826

Northwest Africa

Find: 2006

Achondrite (howardite)

History and physical characteristics: A 344 g fully crusted stone with fine-grained, light grey interior was purchased in Tucson at the Tucson Gem and Mineral Show in January 2007.

Petrography: (T. Bunch and J. Wittke, NAU) Consists mostly of two major eucrite lithologies and diogenitic fragments that display complicated sector and reverse zoning. The medium-grained eucrite (lithology A) is enriched in ilmenite and chromite and contains polygonized pyroxene, plagioclase is partially converted to maskelynite. Eucrite lithology (B) is less shocked and contains pigeonite with well-developed exsolution lamellae and is present as matrix fragments. Diogenitic fragments consist of those that are unzoned, those that are sector zoned, and several large fragments that show dramatic reverse zoning and patches of augite. The weathering grade is low.

Mineral compositions: Lithology (A) orthopyroxene host, Fs50.3Wo1.3 (FeO/MnO = 31), lamellae, Fs23.7Wo45.2. chromite cr# = 63 and plagioclase is An93.8 – 97.8. Lithology (B) Ca-poor pyroxene is Fs40.2Wo4.6 (FeO/MnO = 29) and the lamellae are Fs28.3Wo30.1. Sector zoned orthopyroxene cores are Fs25.3Wo2.6 (FeO/MnO = 28) and rims are Fs36.9–44.6Wo2.3–3.2. Most pigeonite cores with reverse zoning are Fs45Wo14, rims are Fs32.5Wo19, and included augite is Fs29 Wo35.7. One FeO-rich orthopyroxene grain has a core of Fa70.5Wo2.8 (FeO/MnO = 35) and a rim of Fs56.6Wo2.8.

Classification: Achondrite (howardite).

Type specimen: A 21.3 g specimen is on deposit at NAU. The main mass holder is anonymous.

Data from:
  Table 2
  Line 68:
Mass (g):344
Shock stage:moderate
Classifier:T. Bunch and J. Wittke, NAU
Type spec mass (g):21.3
Type spec location:NAU
   and collections
NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012)
References: Published in Meteoritical Bulletin, no. 94, MAPS 43, 1551-1588 (2008)
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     This is 1 of 7810 approved meteorites from (Northwest Africa) (plus 1971 unapproved names)

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