Meteoritical Bulletin: Entry for Northwest Africa 7909

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Northwest Africa 7909

Basic information

Name: Northwest Africa 7909
This is an OFFICIAL meteorite name.
Abbreviation: NWA 7909
Observed fall: No
Year found: 2004
Country: (Northwest Africa)
Mass: 168 g

Classification
history:

Meteoritical Bulletin:	MB 102	(2013)	Mesosiderite-C2
Recommended:			Mesosiderite-C2 [explanation]

This is 1 of 5 approved meteorites classified as Mesosiderite-C2. [show all]
Search for other: Class C mesosiderites, Mesosiderites, and Metal-rich meteorites

Comments:

Approved 27 Jul 2013

Writeup

help

Writeup from MB 102:

Northwest Africa 7909 (NWA 7909)

(Northwest Africa)

Purchased: 2004

Classification: Mesosiderite (group C2)

History: The sample was purchased from a Moroccan trader by Mr. Thompson, and a portion was donated to Cascadia on May 3, 2004.

Physical characteristics: The hand specimen has faceted dark surfaces and brownish, broken faces; cut faces show rust splotches.

Petrography: (A.Ruzicka and K. Farley, Cascadia) Thin-section examination shows a silicate-metal breccia with ~15-20% metal, ~2-5% troilite, and lightly deformed low-Ca pyroxene present in both mineral and lithic clasts, set in a granoblastic groundmass of pyroxene and subordinate plagioclase. Low-Ca pyroxene often contains exsolution lamellae or blebs of high-Ca pyroxene. Metal is <20% altered (grade W1).

Geochemistry: Phase compositions are relatively equilibrated: low-Ca pyroxene Wo_2.7±0.5Fs_23.7±1.1Fe/Mn =26.7±4.1 (N=32), plagioclase An_90.8±1.8Or_0.04±0.3(N=14) (atomic units).

Classification: Stony-iron (mesosiderite). Textures and mineralogy suggest a relatively uncommon group C mesosiderite (dominated by low-Ca pyroxene) of textural type 2.

Specimens: 33.3 g and one polished thin section at Cascadia. Thompson holds the main mass.

Data from:
  MB102
  Table 0
  Line 0:

Place of purchase:	Morocco
Date:	P 2004
Mass (g):	168
Pieces:	1
Class:	Mesosiderite-C2
Shock stage:	low
Weathering grade:	W1
Ferrosilite (mol%):	23.7±1.1
Wollastonite (mol%):	2.7±0.5
Classifier:	A. Ruzicka, Cascadia
Type spec mass (g):	33.3
Type spec location:	Cascadia
Main mass:	Thompson
Comments:	Lab number CML0202, Field number KH003.; submitted by A. Ruzicka

Institutions
and collections

Cascadia: Cascadia Meteorite Laboratory, Portland State University, Department of Geology, Room 17 Cramer Hall, 1721 SW Broadway, Portland, OR 97201, United States; Website (institutional address; updated 28 Oct 2011)
Thompson: Edwin Thompson, 5150 Dawn St., Lake Oswego, OR 97035, United States (private address)

Catalogs:

References:

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

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Geography:

Coordinates:

Unknown.

Statistics:
This is 1 of 9429 approved meteorites from (Northwest Africa) (plus 1876 unapproved names)

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