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Northwest Africa 12861
Basic information Name: Northwest Africa 12861
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12861
Observed fall: No
Year found: 2014
Country: (Northwest Africa)
Mass:help 29 g
Classification
  history:
Recommended:  CM2    [explanation]

This is 1 of 532 approved meteorites classified as CM2.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 2), CM chondrites, and CM-CO clan chondrites
Comments: Approved 21 Sep 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12861 (NWA 12861)

(Northwest Africa)

Purchased: 2014

Classification: Carbonaceous chondrite (CM2)

History: Marc Jost purchased the 28.97 g sample from sellers in Sidi Ifni, Morocco, March, 2014.

Physical characteristics: The sample has an irregular rounded shape and is coated in a flow-lined, black contraction-cracked fusion crust. The cut face shows the interior has a chondritic texture composed of a mostly small chondrules and CAIs set within a black fine-grained matrix.

Petrography: Description and classification (A. Love, App) Sample has a brecciated chondritic texture composed of chondrules, fragments, and CAIs distributed throughout a black fine-grained matrix (~60 vol%). Chondrules have an average apparent diameter of 226 µm (N=33) and are primarily porphyritic chondrules with altered mesostasis. All components are surrounded by fine-grained, dust mantles. Additional minerals are: pentlandite, calcite, chromite, tochilinite, pyrrhotite, kamacite.

Geochemistry: Olivine (Type I Chondrules Fa0.7±0.2 (Fa0.6-1.0), N=5, Type II chondrules Fa29.0±9.9 (Fa13.7-44.6), Cr2O3 in ferroan olivines=0.4±0.1, N=11), low Ca pyroxene Fs6.1±10.4Wo1.1±0.9 (Fs0.7-39.0Wo0.3-4.0, N=14).

Classification: Carbonaceous chondrite (CM2) Based on matrix abundance, chondrule size, mineralogy and magnetic susceptibility, this is a CM carbonaceous chondrite. Based on the abundance of unaltered silicates this is a CM2.

Specimens: Marc Jost (SJS) holds the main mass. An end cut weighing 7.48 g and a polished mount are on deposit at App.

Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:Sidi Info, Morocco
Date:P 2014
Mass (g):28.97
Pieces:1
Class:CM2
Shock stage:low
Weathering grade:low
Fayalite (mol%):0.7±0.2; 29.0±9.9
Ferrosilite (mol%):6.1±10.4
Wollastonite (mol%):1.1±0.9
Magnetic suscept.:4.16
Classifier:A. Love, App
Type spec mass (g):7.48
Type spec location:App
Main mass:Marc Jost (SJS)
Finder:Unknown
Comments:Submitted by Anthony Love
Institutions
   and collections
App: Department of Geology, 572 Rivers St., Appalachian State University, Boone, NC 28608, United States (institutional address; updated 7 Mar 2013)
SJS: Space Jewels Switzerland, 2555 Brügg, Switzerland (private address; updated 3 Jan 2010)
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 6968 approved meteorites from (Northwest Africa) (plus 2012 unapproved names)

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