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Northwest Africa 11905
Basic information Name: Northwest Africa 11905
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11905
Observed fall: No
Year found: 2017
Country: (Northwest Africa)
Mass:help 6.97 kg
Classification
  history:
Recommended:  LL3.10-5    [explanation]

This is the only approved meteorite classified as LL3.10-5.
Search for other: LL chondrites, LL chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
Comments: Approved 2 Sep 2018
Writeuphelp
Writeup from MB 107:

Northwest Africa 11905 (NWA 11905)

(Northwest Africa)

Purchased: 2017

Classification: LL3.10-5

History: Purchased by Matthew Martin, February 2017, in Tucson from a Moroccan meteorite dealer.

Physical characteristics: Single stone. Saw cuts show a breccia of visually different chondrite clasts set in a host chondrite groundmass. Some of the clasts appear to be texturally equilibrated with less distinct chondrules, whereas others resemble type-3 lithologies with densely packed chondrules. The host groundmass contains numerous large, distinct, well-formed chondrules.

Petrography: (C. Agee, UNM) Microprobe examination of several polished mounts shows three group LL lithologies present: Lithology 1 is LL3.10; Lithology 2 is LL5; and Lithology 3 makes up the host groundmass and is LL3. Lithology 1 has numerous porphyritic chondrules, most with mesostasis or glass and abundant opaque matrix. The apparent mean chondrule diameter in Lithology 1 is 900±400 μm, n=31. Lithology 2 has texturally equilibrated chondrules and plagioclase grains up to 25 μm. Lithology 3 (host) has numerous porphyritic chondrules, many with mesostasis, fine-grained plagioclase also detected.

Geochemistry: (C. Agee, UNM) Lithology 1: all olivine Fa14.0±11.0, Fe/Mn=41±15, n=44; ferroan chondrule olivine Fa17.3±9.9, Fe/Mn=45±13, Cr2O3=0.32±0.20 (wt%), n=35; low-Ca pyroxene Fs11.1±10.0Wo1.1±0.8, n=12. Lithology 2: olivine Fa30.7±0.6, Fe/Mn=60±2, n=19; low-Ca pyroxene Fs24.9±0.3Wo1.3±0.9, n=12. Lithology 3: olivine Fa27.9±3.0, Fe/Mn=57±15, n=8; low-Ca pyroxene Fs24.3±1.8Wo2.1±3.5, n=4.

Classification: Ordinary chondrite (LL3.10-LL3-LL5), LL-group genomict breccia. Type 3.10 for Lithology 1 is based on the mean value of Cr2O3 in ferroan chondrule olivine and the 1-sigma standard deviation, (Grossman and Brearley, 2005), a similar petrologic type to NWA 1756 (LL3.10), NWA 3127 (LL3.10), RC 075 (H3.10), and MET 96503 (L3.10). Estimated type for Lithology 3 is 3.8/3.9 based on the scatter in olivine composition.

Specimens: 48.5 g on deposit at UNM, Matthew Martin holds the main mass.

Bibliography:
  • Grossman J.N. and Brearley A.J. (2005) The onset of metamorphism in ordinary and carbonaceous chondrites. Meteorit. Planet. Sci. 40, 87-122. (link)
Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Tucson
Date:P 2017
Mass (g):6974
Pieces:1
Class:LL3.10-5
Shock stage:S3
Weathering grade:W2
Fayalite (mol%):14.0±11.0
Ferrosilite (mol%):11.1±10.0
Wollastonite (mol%):1.1±0.8
Classifier:C. Agee, UNM
Type spec mass (g):48.5
Type spec location:UNM
Main mass:Matthew Martin
Comments:Submitted by C. Agee
Institutions
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
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 6506 approved meteorites from (Northwest Africa) (plus 2021 unapproved names)

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