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Northwest Africa 12971
Basic information Name: Northwest Africa 12971
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12971
Observed fall: No
Year found: 2019
Country: (Northwest Africa)
Mass:help 280 g
Classification
  history:
Recommended:  Lunar (troct. melt rock)    [explanation]

This is the only approved meteorite classified as Lunar (troct. melt rock).
Search for other: Lunar meteorites
Comments: Approved 23 Dec 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12971 (NWA 12971)

(Northwest Africa)

Purchased: 2019 Apr

Classification: Lunar (troctolitic melt rock)

History: Purchased jointly by Craig Zlimen, Mark Lyon and Matthew Stream in April 2019 from a Moroccan dealer.

Physical characteristics: A single light gray stone (280 g) with visible vesicles and light brown weathering products on one side. The fresh interior is composed predominantly of vesicular melt rock which contains some clast-like regions of coarser grained melt rock.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Very fine-grained (grainsize up to 5 µm), microvesicular melt-textured specimen composed predominantly of anorthite plus subordinate olivine and accessory pigeonite, augite, chromite (exhibiting zoning from Ti-bearing cores to Ti-free rims), troilite and pyrrhotite. No intact clasts were observed anywhere in the entire 5 cm diameter slice examined by microprobe imaging, but there are sporadic coarser-grained (up to 40 µm) melt-textured regions.

Geochemistry: Anorthite (An97.2-97.7Or0.0, N = 2), olivine (Fa24.9-35.5, FeO/MnO = 77-99, N = 6), magnesian olivine core (Fa19.0, FeO/MnO = 98), ferroan olivine rim (Fa38.3, FeO/MnO = 80), pigeonite (Fs26.2Wo19.4, FeO/MnO = 44), augite (Fs19.8-35.1Wo35.5±0.0, FeO/MnO = 43-55, N =2).

Classification: Lunar (troctolitic melt rock). The predominance of anorthite and olivine indicates a troctolitic bulk composition. The texture and apparent absence of clasts are consistent with crystallization from a totally molten state.

Specimens: 22.3 g in the form of a large polished slice at UWB; remainder with Mr. C. Zlimen, Mr. M. Lyon and Mr. M. Stream.

Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2019 Apr
Mass (g):280
Pieces:1
Class:Lunar (troctolitic melt rock)
Shock stage:high
Weathering grade:low
Fayalite (mol%):24.9-35.5
Ferrosilite (mol%):26.4; 19.8-35.1
Wollastonite (mol%):19.4; 35.5-35.6
Classifier:A. Irving, UWS, and P. Carpenter, WUSL
Type spec mass (g):22.3
Type spec location:UWB
Main mass:C. Zlimen/M. Lyon/M. Stream
Comments:Work name ZLI20; submitted by A. Irving
Institutions
   and collections
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
WUSL: Washington Univ., One Brookings Drive, St. Louis, MO 63130, United States (institutional address; updated 17 Oct 2011)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
Catalogs:
References: Published in Meteoritical Bulletin, no. 108, in preparation (2019)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7100 approved meteorites from (Northwest Africa) (plus 2005 unapproved names)

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