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Northwest Africa 11858
Basic information Name: Northwest Africa 11858
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11858
Observed fall: No
Year found: 2008
Country: Morocco
Mass:help 454 g
Classification
  history:
Recommended:  Howardite    [explanation]

This is 1 of 360 approved meteorites classified as Howardite.   [show all]
Search for other: Achondrites, HED achondrites, and Howardites
Comments: Approved 8 Jul 2018
Writeuphelp
Writeup from MB 107:

Northwest Africa 11858 (NWA 11858)

Morocco

Purchased: 2008

Classification: HED achondrite (Howardite)

History: The meteorite was purchased at the Munich show in 2008 from a Moroccan meteorite dealer from Rissani.

Physical characteristics: The main mass is approximately 4 × 4 × 10 cm, and is almost completely covered in fusion crust, some of which is dark brown and glassy with flow lines. Minor evidence of terrestrial weathering is present as red-brown straining and adhered dust. Cut surfaces reveal numerous, mostly gray clasts set in a fine-grained, light-gray matrix.

Petrography: (C. Herd and J. Hamilton, UAb) Well-consolidated breccia of clasts up to 5 mm in longest dimension of diogenite (~25 vol%), unequilibrated eucrite (~10 vol%), equilibrated eucrite (~10 vol%), cumulate gabbroic eucrite (~10 vol%), and impact melt, as well as grains of anorthitic plagioclase, olivine, chromite, sulfide, and FeNi metal. All plagioclase has been transformed to maskelynite, and strong mosaicism is common. Fine-grained recrystallized areas of some gabbroic eucrite clasts indicate shock melting.

Geochemistry: (C. Herd, UAb) Diogenite orthopyroxene Fs27±3Wo2.6±0.8, Fe/Mn=32±2, n=23, eucrite pigeonite average Fs48±10Wo6±3, Fe/Mn=32±2, range Fs32-63, n=32, eucrite augite Fs40±10Wo28±10, Fe/Mn=32±1, n=10; plagioclase An88±3Ab11±3Or0.5±0.3, n=21; high-Ti (15 wt% TiO2) and low-Ti (0.8 wt% TiO2) chromite.

Classification: Achondrite (howardite)

Specimens: Type specimen of 21.3 g, including one thin section, is at UAb. Main mass at JTESM.

Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Munich
Date:P 2008
Mass (g):453.5
Pieces:1
Class:Howardite
Shock stage:moderate
Weathering grade:low
Classifier:C. Herd and J. Hamilton, UAb
Type spec mass (g):21.3
Type spec location:UAb
Main mass:Joshua Tree Museum
Comments:Submitted by C. Herd
Institutions
   and collections
UAb: 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB, T6G 2E3, Canada, Canada; Website (institutional address; updated 17 Oct 2011)
JTESM: Joshua Tree Earth And Space Museum PO BOX 101, Lakeville, IN 46536, United States (institutional address; updated 17 Dec 2016)
Catalogs:
References: Published in Meteoritical Bulletin, no. 107, in preparation (2018)
Find references in NASA ADS:
Find references in Google Scholar:
Geography:

Morocco
Coordinates:Unknown.

Statistics:
     This is 1 of 1312 approved meteorites from Morocco (plus 14 unapproved names) (plus 1 impact crater)

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