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Allan Hills A81189
Basic information Name: Allan Hills A81189
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA81189
This meteorite may also be called Allan Hills 81189 (ALH 81189) in publications.

Observed fall: No
Year found: 1981
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 2.6 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 7(2)  (1984)  E4
AMN 17(1)  (1994)  EH3
Meteoritical Bulletin:  MB 76  (1994)  EH3
NHM Catalogue:  5th Edition  (2000)  EH3
MetBase:  v. 7.1  (2006)  EH3
Recommended:  EH3    [explanation]

This is 1 of 138 approved meteorites classified as EH3.   [show all]
Search for other: EH chondrites, Enstatite chondrites, Enstatite chondrites (type 3), and Enstatite-rich meteorites
Writeuphelp
Writeup from AMN 7(2):

Sample No.: ALHA81189

Location: Allan Hills

Field No.: 1582

Weight (gms): 2.6

Meteorite Type: E4 Chondrite

Physical Description: Roberta Score

No fusion crust remains on this fractured reddish brown colored stone. Dimensions: 2 x 1.1 x 0.5 cm

 

Petrographic Description: Brian Mason

The section shows an aggregate of chondrules, chondrule fragments, and mineral grains set in an opaque matrix. The chondrules range up to 0.9 mm in diameter; most of them consist of granular pyroxene (sometimes with a little olivine), but a few are made up of nickel-iron and troilite. The matrix consists largely of nickel-iron and troilite, with a considerable amount of limonite formed by weathering of the metal. Microprobe analyses show that the pyroxene is close to MgSiO3 in composition (FeO 0.5-4.5, mean 1.9%; A12O3 0.02-2.4, mean 0.7%; CaO 0.1- 0.7, mean 0.3%; TiO2 0-0.13, mean 0.08%; MnO 0.07-0.22, mean 0.15%). Most of the olivine grains are close to Mg2SiO4 in composition (FeO 0.7-6.4%). One grain of a silica polymorph was analyzed. Since part of the pyroxene is polysynthetically twinned clinoenstatite, the meteorite is tentatively classified as an E4 chondrite; however, it shows some similarities to Kakangari, classified by Graham et al. (Mineralogical Magazine, V.41, p. 201, 1977) as a forsterite chondrite.

Data from:
  MB76
  Table 2
  Line 712:
Origin or pseudonym:Main icefield
Mass (g):2.6
Class:EH3
Weathering grade:C
Fayalite (mol%):2
Ferrosilite (mol%):3
Comments:81189 pairing group
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 7(2) (1984), 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° 43' 24"S, 159° 16' 30"E)
Note: the NHM and MetBase coordinates are 10.1 km apart

Statistics:
     This is 1 of 40719 approved meteorites from Antarctica (plus 4494 unapproved names)
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