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Allan Hills A77261
Basic information Name: Allan Hills A77261
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77261
This meteorite may also be called Allan Hills 77261 (ALH 77261) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 412 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 2(1)  (1979)  L6
Meteoritical Bulletin:  MB 76  (1994)  L6
NHM Catalogue:  5th Edition  (2000)  L6
MetBase:  v. 7.1  (2006)  L6
Recommended:  L6    [explanation]

This is 1 of 10989 approved meteorites (plus 6 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)
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.: ALHA77261

Location: Allan Hills

Field No.: 77123021

Weight (gms): 411.7

Meteorite Type: L6 Chondrite

 

Physical Description:

The stone is angular and ~8.5x5.0x5.5 cm. Fusion crust covers ~75% of the sample, is dull black and approximately 0.5 mm thick. In places the fusion crust has weathered to a reddish color. Polygonal fractures are present on all surfaces with fusion crust. The surfaces devoid of fusion crust are polished. One large fracture penetrates the entire stone. A few weathered, reddish-brown, chondrules (?), up to as much as 0.5 cm, are apparent on the stone. Cleaving reveals fresh matrix material that is grayish-white and contains small metallic flakes. The exterior weathering penetrates the specimen up to a depth of 2.5 cm. One irregular (0.5 cm in maximum length), gray, lithic clast(?) is apparent on the cleaved surface.

 

Petrographic Description: Brian Mason

The section shows sparse and poorly-defined chondrules, merging with the granular groundmass, which consists largely of olivine and orthopyroxene with minor sub-equal amounts of nickel-iron and troilite; small grains of plagioclase are scattered throughout the groundmass. About one-third of the section is bordered by well-developed fusion crust, up to 0.6 mm thick. A little limonite and limonitic staining is present, concentrated around the nickel-iron grains. Microprobe analyses show olivine (Fa24), orthopyroxene (Fs21), and plagioclase (An11) of uniform composition; accessory merrillite was identified with the microprobe. The meteorite is classified as an L6 chondrite.

Data from:
  MB76
  Table 2
  Line 212:
Origin or pseudonym:Main icefield
Mass (g):411.7
Class:L6
Weathering grade:B
Fayalite (mol%):24
Ferrosilite (mol%):21
Comments:26Al=36±4; NTL=14.0±0.3
Catalogs:
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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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