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Allan Hills A77254
Basic information Name: Allan Hills A77254
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77254
This meteorite may also be called Allan Hills 77254 (ALH 77254) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 246 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 2(1)  (1979)  L5
Meteoritical Bulletin:  MB 76  (1994)  L5
NHM Catalogue:  5th Edition  (2000)  L5
MetBase:  v. 7.1  (2006)  L5
Recommended:  L5    [explanation]

This is 1 of 6534 approved meteorites (plus 4 unapproved names) classified as L5.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeuphelp
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.: ALHA77254

Location: Allan Hills

Field No.: 77122704

Weight (gms): 245.8

Meteorite Type: L5 Chondrite

 

Physical Description:

Very thin, dull, black fusion crust is present on two surfaces (T&N) of the meteorite. The surfaces are free of fusion crust, have a dull, orangish-brown weathering patina, with the exception of the B surface, which is a shiny orangish-brown. From field photographs it was determined that this angular specimen had its B surface in contact with the ice at the time of recovery. The B surface has slickensides. The specimen is 10.5x5.0x4.0 cm. Many inclusions are visible on the sawed surface of the meteorite, which range to as much as 1 cm in length. Discoloration, due to weathering, of the outer most material was observed to a depth of approximately 1.5 cm along the S surface.

 

Petrographic Description: Brian Mason

The section shows well-developed chondritic structure, the chondrules ranging from 0.3-2.1 mm in diameter; a variety of types is present, the commonest being barred olivine, granular olivine and olivine-pyroxene, and radiating pyroxene. The chondrules are set in a granular matrix of olivine and orthopyroxene, with minor subequal amounts of nickel-iron and troilite. Limonitic staining and a few patches of red-brown limonite are associated with the metal grains. Fusion crust is present along one edge of the section. Microprobe analyses show olivine (Fa23) and orthopyroxene (Fs20) of essentially uniform composition. The meteorite is classified as an L5 chondrite.

Data from:
  MB76
  Table 2
  Line 205:
Origin or pseudonym:Main icefield
Mass (g):245.8
Class:L5
Weathering grade:A/B
Fayalite (mol%):23
Ferrosilite (mol%):20
Comments:26Al=53±2
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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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Geography:

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

Statistics:
     This is 1 of 39173 approved meteorites from Antarctica (plus 5051 unapproved names)
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