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Northwest Africa 12281
Basic information Name: Northwest Africa 12281
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12281
Observed fall: No
Year found: 2013
Country: (Northwest Africa)
Mass:help 30.6 g
Classification
  history:
Recommended:  LL3    [explanation]

This is 1 of 303 approved meteorites classified as LL3.   [show all]
Search for other: LL chondrites, LL chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
Comments: Approved 17 Nov 2018
Writeuphelp
Writeup from MB 107:

Northwest Africa 12281 (NWA 12281)

(Northwest Africa)

Purchased: 2013

Classification: Ordinary chondrite (LL3)

History: Acquired from Ruben Garcia from 2013 Tucson Gem and Mineral Show.

Physical characteristics: Sub-rounded, 30.6 g meteorite partially covered in fusion crust. Interior is dominantly light colored with well-developed chondrules and mineral fragments supported by a sparse dark matrix. Metals and sulfides fine-grained. Weathering is heterogeneous and is dominantly W1 with patches of W3.

Petrography: (Bercovici, H., Dolinschi, J., Dunham, E., Franco, G., Garani, J., Loescher, G., ASU): Visually, the meteorite is estimated to be 80% chondrules and fragments, 16% matrix, and 3% opaques. Chondrules typically 0.2 to 1.5 mm in diameter, with an estimated mean of 0.8 mm. Range of chondrules types present including PP, PO, POP, BO, and RP. Some PO chondrules contain purple (plane polarized light) glass. Several chondrules are mantled by sulfides with minor metal. The largest chondrule (9 × 5 mm) is composed of a barred olivine core, PO mantle, and porphyritic low-Ca pyroxene rim. Another chondrule (3 × 4 mm troilite-mantled PO) contains euhedral olivine phenocrysts that have a comb-like overgrowth of olivine (with different BSE brightness) protruding into the devitrified mesostatis. Sulfide is more abundant than metal. Metal and troilite occur in three settings: fine-grained and dispersed in the matrix; rounded grains to 100 microns; and rarely as nodules. The largest nodule (1.5 × 1 mm) consists of a troilite with rounded grains of kamacite. This nodule contains a few grains (to 20 μm) of native copper. Troilite is polycrystalline with occasional shock twins. Shock grade consistent with S2 and weathering with W2/3.

Geochemistry: Olivine Fa20.0±6.2, range Fa12.0-29.9. Cr2O3 in olivine grain cores is 0.62±0.07, range 0.46-0.69, n=10. Low-Ca pyroxene Fs15.7±7.8Wo1.4±1.2, range Fs1.9-33.7Wo0.2-4.8, n=49. High-Ca pyroxene Fs17.4±8.6 Wo16.1±9.5, range Fs11.0-42.1Wo5.1-41.2, n = 18. Feldspar grains, found in only one chondrule, are An97.9±2.5Ab2.1±2.5, ranging An95.1-100.0Ab0.0-4.8, n=3. Metal compositions in wt% are Fe78.46±14.98Ni21.14±14.91Co0.40±0.14 n=5.

Classification: LL based on he low metal content. Estimated petrologic type of 3.4 based on Fa and Fs spread and Cr2O3 content in olivine grain cores.

Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Tucson, Arizona
Date:P 2013
Mass (g):30.6
Pieces:1
Class:LL3
Shock stage:S1
Weathering grade:W2
Fayalite (mol%):20.0±6.2
Ferrosilite (mol%):15.7±7.8
Wollastonite (mol%):1.4±1.2
Classifier:Bercovici, H., Dolinschi, J., Dunham, E., Franco, G., Garani, J., Loescher, G.
Type spec mass (g):30.6
Type spec location:ASU
Main mass:ASU
Finder:anonymous
Comments:Submitted by L. Garvie
Institutions
   and collections
ASU: Center for Meteorite Studies, Arizona State University, Tempe, Arizona 85287-1404, United States; Website (institutional address; updated 14 Jan 2012)
Catalogs:
References: Published in Meteoritical Bulletin, no. 107, in preparation (2018)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 6559 approved meteorites from (Northwest Africa) (plus 2021 unapproved names)

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