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Northwest Africa 12282
Basic information Name: Northwest Africa 12282
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12282
Observed fall: No
Year found: 2016
Country: (Northwest Africa)
Mass:help 141.5 g
Meteoritical Bulletin:  MB 107  (2018)  Eucrite-pmict
Recommended:  Eucrite-pmict    [explanation]

This is 1 of 355 approved meteorites classified as Eucrite-pmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 2 Dec 2018
Writeup from MB 107:

Northwest Africa 12282 (NWA 12282)

(Northwest Africa)

Find: 2016

Classification: HED achondrite (Eucrite, polymict)

History: Purchased by Michael Farmer from a Moroccan meteorite dealer at the 2016 Tucson Gem and Mineral show.

Physical characteristics: Sand-blasted, angular, orange-stained 141.5 g meteorite with patches of fusion crust. Light-colored clasts to 8 mm readily visible at the surface of the stone and supported by a gray matrix. Fresh stone with low weathering.

Petrography: (Dillon, S., Dunham, E., Fitch, R., Karageozian, M., Sedler, M., Teichert, Z., ASU): The meteorite is a breccia dominated by angular to sub-rounded grains and clasts to 8 mm. The petrography is based on two slices (4 × 3 cm and 4 × 4 cm), and a polished mount. The 4 × 3 cm slice is light colored with angular to sub-angular clasts to 4 mm in a poorly sorted clastic matrix dominated by pyroxene and plagioclase. The 4 × 4 cm slice is petrographically more varied with a range of clast textures (subophitic, diabasic, granulitic) supported by the eucritic debris. This slice has a prominent 6 × 5 mm subangular fine-grained dark clast containing a 3-mm spherical fine-grained clast with similar mineralogy as the bulk eucrite. Accessory minerals include silica, troilite, chromite, and ilmenite. The majority of the pyroxene grains exhibit exsolution lamellae. Plagioclase shows extensive twinning. Pyroxene grains are primarily Ca-poor pyroxene with Ca-rich pyroxene present in exsolution lamellae. Plagioclase grains are primarily anorthite rich end members. The sample has a low shock grade; one melt clast within a pyroxene clast is present and is potentially representative of a previous higher-stage shock event.

Geochemistry: Pyroxene without exsolution lamellae is pigeonite Fs52.6±4.4Wo10.4±5.6, range Fs43.7-55.8Wo6.5-22.0, FeO/MnO=33.2±2.2, n=8. Pyroxene with exsolution lamellae is predominantly clinopyroxene Fs57.2±0.7Wo4.4±0.9, range Fs55.8-58.2Wo2.7-5.4, FeO/MnO=33.0±2.1, n=12, the lamellae are orthopyroxene Fs27.3±0.9Wo41.9±0.7, range Fs26.3-28.8Wo40.7-42.8, FeO/MnO=34.1±1.7, n=8. Plagioclase has composition An88.5±6.0, n = 18.

Specimens: An original mass of 141.5 g was acquired by MFarmer; 21.99 g and one thin section is held by ASU. The main mass is held by Michael Farmer.

Data from:
  Table 0
  Line 0:
Place of purchase:Tucson, Arizona
Mass (g):141.5
Shock stage:low
Weathering grade:low
Classifier:S. Dillon, E. Dunham, R. Fitch, M. Karageozian, M. Sedler, Z. Teichert, ASU
Type spec mass (g):21.99
Type spec location:ASU
Main mass:Michael Farmer
Comments:Submitted by L. Garvie
   and collections
ASU: Center for Meteorite Studies, Arizona State University, Tempe, Arizona 85287-1404, United States; Website (institutional address; updated 14 Jan 2012)
MFarmer: Michael Farmer, P.O. Box 86059, Tucson, AZ 85754-6059, United States; Website (private address)
References: Published in Meteoritical Bulletin, no. 107, MAPS 55, 460-462
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     This is 1 of 7810 approved meteorites from (Northwest Africa) (plus 1971 unapproved names)

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