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Northwest Africa 6157
Basic information Name: Northwest Africa 6157
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 6157
Observed fall: No
Year found: 2010
Country: Algeria
Mass:help 42 g
Meteoritical Bulletin:  MB 98  (2010)  Diogenite, olivine
Recommended:  Diogenite-olivine    [explanation]

This is 1 of 17 approved meteorites classified as Diogenite-olivine.   [show all]
Search for other: Achondrites, Diogenites, and HED achondrites
Comments: Approved 10 May 2010
Writeup from MB 98:

Northwest Africa 6157


Purchased: Feb 2010

Classification: HED achondrite (diogenite)

History: Purportedly found in Algeria, and purchased in February 2010 by Michael MFarmer from a Moroccan dealer at the Tucson Gem and Mineral Show.

Physical characteristics: A single dense stone weighing 42 g.

Petrography: (A. Irving and S. Kuehner, UWS) Coarse grained (up to 7 mm) with a primarily protogranular texture. Composed of 50 vol% olivine and 45 vol% low-Ca pyroxene with accessory Ca-pyroxene, chromite, troilite and metal (kamacite). Plagioclase is absent. Some veinlets of terrestrial calcite crosscut the specimen.

Geochemistry: Olivine (Fa29.3-30.1, FeO/MnO = 42.1-46.2), low-Ca pyroxene (Fs24.3±0.0Wo2.8, FeO/MnO = 26.0-29.4), Ca-pyroxene (Fs11.2Wo42.7, FeO/MnO = 19.7).

Classification: Achondrite (olivine-rich diogenite). Although the mineral compositions are very similar to those in NWA 4223, this stone is texturally different and evidently not paired with other olivine-rich diogenites.

Specimens: 8.9 g of sample and one polished thin section are on deposit at UWS. MFarmer holds the main mass.

Data from:
  Table 1
  Line 49:
Place of purchase:Tucson Gem and Mineral Show
Date:P Feb 2010
Mass (g):42
Class:Diogenite, olivine
Fayalite (mol%):29.3-30.1
Ferrosilite (mol%):24.3
Wollastonite (mol%):2.8
Classifier:A. Irving, S. Kuehner, UWS
Type spec mass (g):8.9
Type spec location:UWS
Main mass:MFarmer
Comments:Submitted by A. Irving
   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)
MFarmer: Michael Farmer, P.O. Box 86059, Tucson, AZ 85754-6059, United States; Website (private address)
References: Published in Meteoritical Bulletin, no. 98, MAPS 45, 1530-1551 (2010)
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     This is 1 of 1236 approved meteorites from Algeria (plus 29 unapproved names) (plus 4 impact craters)

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