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Northwest Africa 12921
Basic information Name: Northwest Africa 12921
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12921
Observed fall: No
Year found: 2018
Country: (Northwest Africa)
Mass:help 566 g
Classification
  history:
Recommended:  LL7    [explanation]

This is 1 of 63 approved meteorites classified as LL7.   [show all]
Search for other: LL chondrites, LL chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 21 Nov 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12921 (NWA 12921)

(Northwest Africa)

Purchased: 2018

Classification: Ordinary chondrite (LL7)

History: Marc Jost purchased the 566 g stone from Giorgio Tomellieri at the St. Marie aux Mines show in 2018.

Physical characteristics: The rounded sample has a weathered brown exterior. A cut face shows the interior is light green in color and has a crystalline texture with visible flakes of metal and sulfide.

Petrography: Description and classification (A. Love, App): Sample has a fine-grained, poikiloblastic texture composed of: 60 vol% Ol; 25 vol% Ca-poor and Ca-rich pyroxene and 14 vol% albitic plagioclase (avg length 112µm, n=53). Additional minerals are: troilite; pentlandite; chromite (average length 79µm, n=31); merrillite; kamacite and taenite. Recrystallization has overprinted and erased primary chondritic texture.

Geochemistry: (A. Love, App): Olivine (Fa31.6±0.1, Fe/Mn=57.2±1.1, n=12); low Ca pyroxene (Fs26.1±0.2Wo2.7±0.4, CaO=1.1-1.7, n=6); high Ca pyroxene (Fs12.1±0.3Wo41.7±0.7, n=6); plagioclase (An10.9±0.1Or 5.9±0.2, n=2).Oxygen isotopes (K. Ziegler, UNM): analyses of 3 acid-washed mineral separates by laser fluorination gave, respectively, δ17O = 4.373, 4.214, 4.199; δ18O = 5.787, 5.526, 5.472; Δ17O = 1.318, 1.297, 1.310 (data are linearized all per mil).

Classification: Ordinary Chondrite (LL7 C-S2 W1). LL based on oxygen isotopic composition, olivine and pyroxene compositions and magnetic susceptibility. Type 7 based on recrystallized poikiloblastic texture, equilibrated compositions, CaO content of low and high-Ca pyroxenes and size of plagioclase.

Specimens: Marc Jost (SJS) holds the main mass. 2 slices weighing 35.4 g, a polished mount and a polished thin section are on deposit at App.

Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:St. Marie aux Mines
Date:P 2018
Mass (g):566
Pieces:1
Class:LL7
Shock stage:C-S2
Weathering grade:W1
Fayalite (mol%):31.6±0.1
Ferrosilite (mol%):26.1±0.2; 12.1±0.3
Wollastonite (mol%):2.7±0.4; 41.7±0.7
Magnetic suscept.:3.70
Classifier:A. Love, App
Type spec mass (g):35.4
Type spec location:App
Main mass:Marc Jost (SJS)
Finder:Unknown
Comments:Submitted by Anthony Love
Plots: O isotopes:  
Institutions
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
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 7048 approved meteorites from (Northwest Africa) (plus 1998 unapproved names)

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