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Northwest Africa 12778
Basic information Name: Northwest Africa 12778
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12778
Observed fall: No
Year found: 2018
Country: (Northwest Africa)
Mass:help 35.8 g
Meteoritical Bulletin:  MB 108  (2020)  CM2
Recommended:  CM2    [explanation]

This is 1 of 610 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 26 Sep 2019
Writeup from MB 108:

Northwest Africa 12778 (NWA 12778)

(Northwest Africa)

Purchased: 2018

Classification: Carbonaceous chondrite (CM2)

History: Purchased by Matthew Stream from Mike Bandli in 2018, who purchased it from Aziz Habibi at the 2018 Tucson Gem and Mineral Show.

Physical characteristics: Four dark-gray stones. A slice reveals a dark fine-grained interior.

Petrography: (D. Sheikh, FSU) Small chondrules present (mean diameter ~260 µm), isolated mineral fragments (Olivine, low-Ca pyroxene, high Ca-Pyroxene) and small CAIs with fine-grained dust rims set in a dark, abundant matrix. In many chondrules the mesostasis has been aqueously altered to phyllosilicates. The matrix also contains phyllosyllicates as indicated by low microprobe totals.

Geochemistry: (D. Sheikh, FSU) Olivine (Fa11.9±17.0, range Fa0.7-41.4, Cr2O3=0.40±0.13, n=12); low-Ca Pyroxene (Fs3.5±3.3 Wo0.8±0.3, range Fs1.1-5.9Wo0.6-1.0, n=10). Isolated mineral grains of low-Ca Pyroxene (Fs27.8±1.1 Wo0.5±0.1, range Fs26.9-29.0Wo0.4-0.6, n=3) and high-Ca Pyroxene (Fs9.9 Wo9.2, n=1) found in matrix.

Classification: Carbonaceous Chondrite (CM2)

Specimens: 7.22 grams at UCLA; main mass with Matthew Stream.

Data from:
  Table 0
  Line 0:
Place of purchase:Tucson
Date:P 2018
Mass (g):35.8
Shock stage:low
Weathering grade:low
Fayalite (mol%):11.9±17.0 (0.7-41.4, n=12)
Ferrosilite (mol%):3.5±3.3 (1.1-5.9, n=10)
Wollastonite (mol%):0.8±0.3 (0.6-1.0, n=10)
Classifier:D. Sheikh, FSU
Type spec mass (g):7.22
Type spec location:UCLA
Main mass:Matthew Stream
Comments:Submitted by Daniel Sheikh
   and collections
UCLA: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, United States (institutional address; updated 17 Oct 2011)
FSU: Department of Geological Sciences, Florida State University, Tallahassee FL 32306-4100, United States (institutional address; updated 16 Dec 2010)
References: Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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Public domain photographs:
Daniel Sheikh   

     This is 1 of 8509 approved meteorites from (Northwest Africa) (plus 1899 unapproved names)

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