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Allan Hills A77249
Basic information Name: Allan Hills A77249
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77249
This meteorite may also be called Allan Hills 77249 (ALH 77249) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 504 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 2(1)  (1979)  L3
Meteoritical Bulletin:  MB 76  (1994)  L3.5
NHM Catalogue:  5th Edition  (2000)  L3.5
NIPR Catalogue:  2000 Edition  (2000)  L3
MetBase:  v. 7.1  (2006)  L3.5
Recommended:  L3.5    [explanation]

This is 1 of 95 approved meteorites classified as L3.5.   [show all]
Search for other: L chondrites, L chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
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.: ALHA77249

Location: Allan Hills

Field No.: 77122925

Weight (gms): 503.6

Meteorite Type: L3 Chondrite

 

Physical Description:

This is not a complete specimen. The S and T surfaces have very thin, dull, patches of fusion crust. The B surface has thin, shiny black fusion crust, portions of which have weathered to reddish-brown. There are numerous inclusions, both chondrules and lithic clasts, visible through the reddish-brown oxidation rind. The largest chondrule is approximately 0.5 cm in diameter and is lighter colored than the surrounding matrix. A few inclusions that are darker than the matrix are also observed; however, they are not as numerous or as large. The sample is angular, 11.0x6.5x5.0 cm, and has many obvious fractures on the exterior surface.

 

Petrographic Description: Brian Mason

The thin section shows an aggregate of well-defined chondrules, 0.3-2.1 mm in diameter, set in a small amount of fine-grained groundmass. A wide variety of chondrule types is present, the commonest being barred olivine, porphyritic olivine, granular olivine-pyroxene, and fine-grained pyroxene. The olivine chondrules frequently have interstitial glass, usually turbid and partly de-vitrified, but occasionally transparent with a pale brown color. Pyroxene grains show polysynthetic twinning. Sparse nickel-iron and troilite is concentrated on the surfaces of chondrules. Limonitic staining pervades the section, and scattered grains of red-brown limonite are present. Microprobe analyses show a wide range in the composition of olivine (Fa7-Fa35, average Fa17) and pyroxene (Fs2-Fs25, average Fs11). This range of composition, together with the presence of glass and twinned clinopyroxene, indicates type 3, and the small amount of nickel-iron suggests L group; the meteorite is therefore tentatively classified as an L3 chondrite.

Data from:
  MB76
  Table 2
  Line 200:
Origin or pseudonym:Main icefield
Mass (g):503.6
Class:L3.5
Weathering grade:C
Fayalite (mol%):7-35
Ferrosilite (mol%):2-25
Comments:26Al=37±2; 77011 pairing group
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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