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Northwest Africa 11119
Basic information Name: Northwest Africa 11119
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11119
Observed fall: No
Year found: 2017
Country: Mauritania
Mass:help 453 g
Classification
  history:
Recommended:  Achondrite-ung    [explanation]

This is 1 of 81 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 3 Mar 2017
Writeuphelp
Writeup from MB 106:

Northwest Africa 11119 (NWA 11119)

Mauritania

Purchased: 2017

Classification: Ungrouped achondrite

History: Purchased by Abdelhadi Aithiba in Mauritania 2017, reportedly found December 2016.

Physical characteristics: Single stone, partially covered in light green fusion crust, broken surface reveals scattered bright green pyroxene crystals up to 3 mm set in a finer grained matrix with some light-green and gray crystals. Spherical vugs and irregular shaped cavities (lined with crystal faces) were observed, some up to 4 mm. The sample is highly friable.

Petrography: (P. Srinivasan, JSC/UNM) Microprobe examination of a polished mount gives a calculated volume mineralogy of 38% plagioclase, 22% silica phase, 21% high-Ca pyroxene, 18% low-Ca pyroxene, 0.7% oxides (ulvospinel, ilmenite), and 0.3% sulfides. The silica phase, which makes up about 22% by volume of this meteorite, is a mix of tridymite and cristobalite with minor quartz, in proportions of approximately 60% tridymite, 37% cristobalite, 3% quartz. No metal was detected. The major phases occur as subhedral, porphyritic grains surrounded by a fine-grained matrix. The matrix has many acicular and compositionally heterogeneous grains resembling quench melt crystals or exsolution intergrowths. Rare fayalitic olivine was detected in one area of the matrix. The high reported alumina content from the micropropbe data is probably due to tiny oxide inclusions which seem to be abundant. Numerous inclusions with exsolution textures were observed.

Geochemistry: (P. Srinivasan, JSC/UNM) Plagioclase An84.9±9.9Ab14.8±9.5Or0.3±0.5, n=60; silica phase SiO2=96.2±0.6, Al2O3=1.2±0.4 (wt%), n=41; clinoenstatite Fs10±1.3Wo4.6±0.1, Fe/Mn=6.8±0.2, Fe/Mg=0.1±0.02, n=8; Pigeonite Fs52.7±24.6Wo15.8±3.3, Fe/Mn=7.7±1.1, Fe/Mg=8.1±9.5, n=20; augite Fs22.9±20.4Wo33.3±5.7, Fe/Mn=6.8±1.8, Fe/Mg=1.6±3.6, n=167. Porphyritic plagioclase grains contain Na-rich rims. Matrix pyroxene grains are highly zoned, with ~5-35 wt% FeO in a single grain. Major element bulk composition based on modal mineralogy: (all in wt%) SiO2 57.0, TiO2 1.6, Al2O3 12.9, Cr2O3 0.3, FeO 8.6, MnO 1.0, MgO 7.0, CaO 11.0, Na2O 0.7, K2O 0.03, S 0.2. Oxygen isotopes (K. Ziegler, UNM): 4 acid-washed fragments analyzed by laser fluorination gave δ18O= 8.226, 7.781, 8.121, 7.671; δ17O= 3.364, 3.133, 3.398, 3.046; Δ17O= -0.979, -0.975, -0.890, -1.004 (linearized, all per mil, TFL slope=0.528).

Classification: Ungrouped achondrite. This appears to be a unique ungrouped achondrite, It shares similar oxygen isotope values with NWA 7325 and ureilites, however it has a distinct mineralogy with abundant silica phase and an extremely wide range of pyroxene compositions.

Specimens: 23 g, plus a probe mount, on deposit at UNM, Abdelhadi Aithiba holds the main mass.

Data from:
  MB106
  Table 0
  Line 0:
Place of purchase:Mauritania
Date:P 2017
Mass (g):453
Pieces:1
Class:Achondrite-ung
Shock stage:low
Weathering grade:low
Ferrosilite (mol%):10±1.3; 52.7±24.6; 22.9±20.4
Wollastonite (mol%):4.6±0.1; 15.8±3.3; 33.3±5.7
Classifier:C. Agee, UNM
Type spec mass (g):23
Type spec location:UNM
Main mass:Abdelhadi Aithiba
Comments:Submitted by C. Agee
Plots: O isotopes:  
Institutions
   and collections
JSC: Mailcode KT, 2101 NASA Parkway, NASA Johnson Space Center, Houston, TX 77058, United States; Website (institutional address; updated 3 Sep 2013)
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. 106, in preparation (2017)
Find references in NASA ADS:
Find references in Google Scholar:
Geography:

Mauritania
Coordinates:Unknown.

Statistics:
     This is 1 of 88 approved meteorites from Mauritania (plus 2 impact craters)

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