Meteoritical Bulletin: Entry for Northwest Africa 7892

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Northwest Africa 7892

Basic information

Name: Northwest Africa 7892
This is an OFFICIAL meteorite name.
Abbreviation: NWA 7892
Observed fall: No
Year found: 2012
Country: Morocco
Mass: 346 g

Classification
history:

Meteoritical Bulletin:	MB 102	(2013)	CO3.0
Recommended:			CO3.0 [explanation]

This is 1 of 22 approved meteorites classified as CO3.0. [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 3), CM-CO clan chondrites, and CO chondrites

Comments:

Approved 28 Jun 2013

Writeup

help

Writeup from MB 102:

Northwest Africa 7892 (NWA 7892)

Morocco

Purchased: 2012

Classification: Carbonaceous chondrite (CO3.0)

History: Purchased by Abdelhadi Aithiba in Morocco, 2012.

Physical characteristics: Single stone, distinctive polygonal, dark brown weathered fusion crust, saw-cut reveals many small chondrules in a very fine-grained dark-brown matrix.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows many PP, POP, and PO chondrules, most 50-300 μm, irregular shaped or fragmental chondrules common.

Geochemistry: (C. Agee and L. Burkemper, UNM) Random chondrule olivine range Fa_0.3-56.8, mean=Fa_17.5, n=22, chondrule ferroan olivine mean Fa_30.7±13.4, Cr₂O₃=0.39±0.19 wt%, Fe/Mn=95±25, n=35; low-Ca pyroxene range Fs_0.8-41.3, mean Fs_8.0, n=17; aluminous diopside Al₂O₃=8.76 wt%. (Karen Ziegler, UNM) Oxygen isotope mean values of analyses on 2 acid-washed aliquots of bulk sample, 1.2, 1.1 mg, gave δ¹⁷O= -8.851, -9.836, δ¹⁸O= -5.849, -6.906, Δ¹⁷O= -5.763, -6.190, (linearized, all permil).

Classification: Carbonaceous chondrite (CO3.0) estimated 3.05, based on mean Cr₂O₃=0.39 wt% in 35 chondrule ferroan olivines which is higher than that measured in the most primitive CO3 chondrite currently known (ALH 77307), but with higher standard deviation (σ-Cr₂O₃), analogous to the higher σ-Cr₂O₃ reported in type 3.05 ordinary chondrites QUE 97008, MET 00526, and EET 90161 (Grossman and Brearley, 2005). Oxygen isotopes values significant lower than literature CO bulk values, and slightly above the CCAM.

Specimens: 21 g including a probe mount on deposit at UNM, Abdelhadi Aithiba holds the main mass.

Bibliography:

Grossman J.N. and Brearley A.J. (2005) The onset of metamorphism in ordinary and carbonaceous chondrites. Meteorit. Planet. Sci. 40, 87-122. (link)

Data from:
  MB102
  Table 0
  Line 0:

Place of purchase:	Morocco
Date:	P 2012
Mass (g):	346
Pieces:	1
Class:	CO3.0
Fayalite (mol%):	0.3-56.8
Ferrosilite (mol%):	0.8-41.3
Classifier:	C. Agee, UNM
Type spec mass (g):	21
Type spec location:	UNM
Main mass:	Abdelhadi Aithiba
Comments:	Submitted by C. Agee

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)

Catalogs:

References:

Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015

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Geography:

Morocco

Morocco

Coordinates:

Unknown.

Statistics:
This is 1 of 2082 approved meteorites from Morocco (plus 31 unapproved names) (plus 1 impact crater)

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Revision
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