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Northwest Africa 1840
Basic information Name: Northwest Africa 1840
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 1840
Observed fall: No
Year found: 2003
Country: (Northwest Africa)
Mass:help 132.8 g
Classification
  history:
Meteoritical Bulletin:  MB 89  (2005)  Enst achon-ung
MetBase:  v. 7.1  (2006)  Achondrite-ung
Recommended:  Enst achon    [explanation]

This is 1 of 10 approved meteorites classified as Enst achon.   [show all]
Search for other: Achondrites, Enstatite achondrites, and Enstatite-rich meteorites
Writeuphelp
Writeup from MB 89:

Northwest Africa 1840

Morocco

Found 2003

Enstatite achondrite (ungrouped)

A 132.8 g complete and partially crusted stone was purchased in Erfoud, Morocco in August 2003. Description and classification (T. Bunch and J. Wittke, NAU): The meteorite has an igneous texture; it is a brecciated enstatite orthopyroxenite with a series of prominent, parallel compression fractures (0.1 to 0.8 mm spacing) that span the entire sample. These fractures acted as conduits for weathering; most weathering effects are limited to areas that border these fractures.  Mineral modes: enstatite, 92 vol. %; Si-bearing metal, 4 %; plagioclase (maskelynite), 2 %; high Cr-troilite, 2 %; graphite, < 1%. Enstatite, FeO = 0.03 to 0.64 wt. %; CaO = 0.06 to 0.38 wt %.; Cr-rich troilite, Cr = 10.2 to 14.7 wt. % with Mn < 1.15 % and Ti < 1.76 wt. %. Largest metal grains (0.6 – 1.0 mm dia.) have graphite inclusions < 0.1 mm in size; metal, Ni = 6.5 wt. % (range = 6.2 – 6.9), Si = 1.25 wt. % (range = 0.9 – 1.81); plagioclase, An42. None of the exotic sulfides common to aubrites and enstatite chondrites were found. Shock level, S4 (parallel fractures, reduced birefringence, and mottled extinction in enstatite; all plagioclase is maskelynite); weathering grade is W2/3. Specimens: type sample, 21.1 g (NAU); main mass, Oakes.

Data from:
  MB89
  Table 7
  Line 29:
Date:2003
Mass (g):132.8
Pieces:1
Class:Enstatite achondrite
Classifier:
Type spec mass (g):21.1
Institutions
   and collections
NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012)
Oakes: Nelson Oakes, Route 1, House 50C, Uniondale, PA 18470, United States; Website (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 89, MAPS 40, A201-A263 (2005)
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Photos:
CreditPhotos
Photos from the Encyclopedia of Meteorites:
Don Edwards   
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7320 approved meteorites from (Northwest Africa) (plus 1973 unapproved names)

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