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Allan Hills A81009
Basic information Name: Allan Hills A81009
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA81009
This meteorite may also be called Allan Hills 81009 (ALH 81009) in publications.

Observed fall: No
Year found: 1981
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 229 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 6(1)  (1983)  Eucrite
AMN 13(1)  (1990)  Eucrite-pmict?
Meteoritical Bulletin:  MB 76  (1994)  Eucrite-pmict
NHM Catalogue:  5th Edition  (2000)  Eucrite-pmict
MetBase:  v. 7.1  (2006)  Eucrite-pmict
Recommended:  Eucrite-pmict    [explanation]

This is 1 of 339 approved meteorites classified as Eucrite-pmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Writeuphelp
Writeup from AMN 6(1):

Sample No.: ALHA81009

Location: Allan Hills

Field No.: 1500

Weight (gms): 229.0

Meteorite Type: Eucrite

 

Physical Description: Roberta Score

ALHA81009 is completely covered with flow marked black fusion crust. Contained in the light-gray matrix are numerous clasts which are as large as .5 cm in diameter. Oxidation haloes are present. Dimensions: 7 x 5.5 x 3.5 cm.

 

Petrographic Description: Brian Mason

The section consists largely of brown grains of pigeonite up to 1 mm and colorless grains of plagioclase up to 2 mm in a comminuted groundmass of these minerals. Some lithic clasts, up to 3 mm across, are present; most are fine-grained, but a few have coarse gabbroic textures. No evidence of weathering is visible. Microprobe analyses show pyroxene compositions ranging fairly continuously from Wo4En33Fs63 to Wo40En26Fs30; En content shows a limited range (28-37) except for one grain Wo6En47Fs47. Plagioclase composition range is An75-93, mean An86. The meteorite is a eucrite, but it differs from previously described polymict eucrites from the Allan Hills in the range and distribution of pyroxene compositions.

 

[From AMN 7(1):] ALHA81009 Clasts

Several interesting clasts were discovered while processing ALHA81009 (Eucrite). They are now available for allocation. 1) Dark clast with light inclusions; 2) Light gray clast with white and yellowish minerals; 3) Gray area with no clasts. Requests for these specific clasts may be made to the MWG.

Data from:
  MB76
  Table 2
  Line 532:
Origin or pseudonym:Main icefield
Mass (g):229
Class:Eu "pm"
Weathering grade:A
Ferrosilite (mol%):30-63
Comments:76005 pairing group
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 6(1) (1983), JSC, Houston
Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
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Geography:

Antarctica
Coordinates:
     Catalogue of Meteorites:   (76° 43'S, 159° 40'E)
     Recommended::   (76° 41' 52"S, 159° 18' 14"E)
Note: the NHM and MetBase coordinates are 9.6 km apart

Statistics:
     This is 1 of 38937 approved meteorites from Antarctica (plus 5051 unapproved names)
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