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Allan Hills A77231
Basic information Name: Allan Hills A77231
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77231
This meteorite may also be called Allan Hills 77231 (ALH 77231) in publications.

Observed fall: No
Year found: 1977 or 1978
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 9.27 kg
Antarctic Meteorite Newsletter:  AMN 2(1)  (1979)  L6
Meteoritical Bulletin:  MB 76  (1994)  L6
NHM Catalogue:  5th Edition  (2000)  L6
NIPR Catalogue:  2000 Edition  (2000)  L6
MetBase:  v. 7.1  (2006)  L6
Recommended:  L6    [explanation]

This is 1 of 12222 approved meteorites (plus 7 unapproved names) classified as L6.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeup from AMN 2(1):
This text was reprinted from AMN 2(1) in AMN 4(1). In some cases, it may be an updated version from the original.

Sample No.: ALHA77231

Location: Allan Hills

Field No.: Y78010508

Weight (gms): 9270.0

Meteorite Type: L6 Chondrite


Physical Description:

This is a complete specimen, approximately 25.0 x 17.0 x 13.5 cm. All surfaces of the sample are covered with dull black fusion crust. The fusion crust has many polygonal fractures and is approximately 0.5 mm thick. There are several large fractures that cross the surface of the meteorite. There was snow/ice in the fractures when it was removed from cold storage. There are small areas along the fractures where the fusion crust has been removed and reveals greenish-gray material that does not have any obvious inclusions. When the meteorite was sawed a few light color clasts, as much as 1.5 cm in diameter, were observed. The metal in the meteorite has oxidation halos, although the weathering is not extensive.


Petrographic Description: Brian Mason

The thin section shows a granular aggregate of olivine and orthopyroxene, with minor subequal amounts of nickel-iron and troilite, and untwinned plagioclase. Chondrules are present, but their outlines are blurred and merge with the granular material. A little limonite is associated with some of the metal grains. Microprobe analyses show olivine (Fa24), orthopyroxene (Fs21), and plagioclase (An11) of uniform composition. The meteorite is classified as an L6 chondrite.

Data from:
  Table 2
  Line 186:
Origin or pseudonym:Main icefield
Mass (g):9270
Weathering grade:A/Be
Fayalite (mol%):24
Ferrosilite (mol%):21
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References: Published in Antarctic Meteorite Newsletter 2(1) (1979), JSC, Houston
Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
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     Catalogue of Meteorites:   (76° 43'S, 159° 40'E)
     Recommended::   (76° 43'S, 159° 40'E)

     This is 1 of 43700 approved meteorites from Antarctica (plus 3802 unapproved names)
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