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Allan Hills A77305
Basic information Name: Allan Hills A77305
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77305
This meteorite may also be called Allan Hills 77305 (ALH 77305) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 6.44 kg
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 1(3)  (1978)  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 1(3):
This text was reprinted from AMN 1(3) in AMN 4(1). In some cases, it may be an updated version from the original.

Sample No.: ALHA77305

Location: Allan Hills

Field No.: B77123108

Weight (gms): 6444.0

Meteorite Type: L6 Chondrite

 

Physical Description:

Snow ice? was observed in cracks of the meteorite when it was removed from the freezer. The exterior surface does not have a fusion crust with the exception of an ~5 cm diameter area, which is dark and 1-2 mm thick, however, it does have a reddish-brown weathering rind. The iron-oxide staining that is apparent on the exterior surface is heavier adjacent to the several fissures which are present on the surface of the meteorite. It appears that the roundness of the stone may be due to exfoliation. Rounded inclusions are apparent on the surface. It appears that the entire specimen has experienced moderate weathering on the exterior surface. During chipping ~25% of the specimen fell off along a fissure. The interior portion is both weathered and fresh in appearance. Fresh metal is apparent on surfaces not adjacent to fissures. After sawing the specimen, small metal chips were visible throughout the sample. The sample is very hard, even though many parallel cracks run throughout the entire sample.

 

Petrographic Description: Brian Mason

Chondrules are sparse and poorly defined, merging with the granular groundmass. Troilite and nickel-iron are present in minor, approximately equal amounts. About 10% of plagioclase is present, as small untwinned grains. The meteorite is relatively unweathered, with a limited amount of limonitic staining associated with nickel-iron grains. Microprobe analyses show olivine (Fa24) and orthopyroxene (Fs21) of uniform composition.

Data from:
  MB76
  Table 2
  Line 254:
Origin or pseudonym:Main icefield
Mass (g):6444
Class:L6
Weathering grade:B/C
Fayalite (mol%):24
Ferrosilite (mol%):21
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 1(3) (1978), 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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