Meteoritical Bulletin: Entry for Allan Hills 99500

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Allan Hills 99500

Basic information

Name: Allan Hills 99500
This is an OFFICIAL meteorite name.
Abbreviation: ALH 99500
Observed fall: No
Year found: 1999
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass: 13.6 g

Classification
history:

NHM Catalogue:	5th Edition	(2000)	CM2
Antarctic Meteorite Newsletter:	AMN 24(1)	(2001)	CM2
Meteoritical Bulletin:	MB 85	(2001)	CM2
MetBase:	v. 7.1	(2006)	CM2
Recommended:			CM2 [explanation]

This is 1 of 636 approved meteorites classified as CM2. [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 2), CM chondrites, and CM-CO clan chondrites

Writeup

Writeup from AMN 24(1):

Sample No.:	ALH 99500
Location:	Allan Hills
Field No.:	12065
Dimensions (cm):	3.0x1.5x1.5
Weight (g):	13.596
Meteorite Type:	CM2 Chondrite

Macroscopic Description: Kathleen McBride
60% of the exterior of this carbonaceous chondrite has fractured purplish black fusion crust. The exposed interior appears to have a greenish tint. The matrix is made up of soft, chalky black material that has a sulfurous odor. Contained within the matrix are tiny white chondrules.

Thin Section (, 4) Description: Tim McCoy and Linda Welzenbach


Plane-Polarized Light	Cross-Polarized Light

The section consists almost entirely of Fe-rich serpentine, which forms the matrix of the meteorite and has replaced the bulk of most chondrules. A few scattered anhydrous silicates remain. Olivine ranges from Fa_1-47, with many Fa_0-1. The meteorite is a CM2 chondrite. Pairing with ALH 83100 should be considered.

Data from:
  MB85
  Table A1
  Line 13:

Origin or pseudonym:	Far Western
Mass (g):	13.6
Class:	CM2
Weathering grade:	B
Fayalite (mol%):	1-47
Comments:	83100 pairing group

Catalogs:

Search for specimens in the Smithsonian Institution collection (U.S.):	Require SI photo
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References:

Published in Antarctic Meteorite Newsletter 24(1) (2001), JSC, Houston
Published in Meteoritical Bulletin, no. 85, MAPS 36, A293-A322 (2001)

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Photos:

Credit	Photos
Photographs from AMN:
Photograph from unknown source	A photo is in the write-up above
Photos from the Encyclopedia of Meteorites:
Dr Carlton Allen, JSC-KT, NASA

Geography:

Antarctica

Coordinates:
Catalogue of Meteorites:	(76° 43'S, 159° 40'E)
Recommended::	(76° 43'S, 159° 40'E)

Statistics:
This is 1 of 44543 approved meteorites from Antarctica (plus 3802 unapproved names)

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