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Allan Hills A77216
Basic information Name: Allan Hills A77216
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77216
This meteorite may also be called Allan Hills 77216 (ALH 77216) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 1470 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 2(1)  (1979)  L4
AMN 4(1)  (1981)  L3
Meteoritical Bulletin:  MB 76  (1994)  L3.7/3.9
NHM Catalogue:  5th Edition  (2000)  L3.7/3.9
NIPR Catalogue:  2000 Edition  (2000)  L3
MetBase:  v. 7.1  (2006)  L3.7-3.9
Antarctic Meteorite Newsletter:  AMN 33(1)  (2010)  L3.7-3.9
Recommended:  L3.7-3.9    [explanation]

This is the only approved meteorite classified as L3.7-3.9.
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.: ALHA77216

Location: Allan Hills

Field No.: 77122949

Weight (gms): 1470.0

Meteorite Type: L3 Chondrite

 

Physical Description:

Ice was present on the sample when it was removed from cold storage. Dull, black fusion crust (as much as 0.5 mm) covers half the specimen. The sample is approximately 15.0 x 9.0 x 8.0 cm. Field photographs show that the T and N surfaces were in contact with the ice at time of recovery. The overall color of this specimen is greenish-gray. Numerous inclusions (rounded and irregular) ranging to greater than 2.0 cm are apparent on the fracture surfaces, these range from white to whitish-gray to dark gray. The fracture surfaces show varying degrees of weathering, presumably due to different lengths of exposure time. This meteorite is very heterogeneous on a centimeter scale. Many fractures penetrate the sample. No fresh metal was observed when collecting a suitable thin section sample. This specimen resembles ALHA77215, ALHA77217, and ALHA77252.

 

Petrographic Description: Brian Mason

Most of the section shows well-developed chondritic structure, chondrules ranging from 0.3 - 1.2 mm in diameter. The chondritic part contains minor amounts of nickel-iron and troilite; a small amount of limonitic staining is associated with the metal grains. Three enclaves are present; two consist of granular olivine and pyroxene, and measure at least 3 mm across; the third has a maximum of 2 mm, and consists of small grains of olivine and pyroxene in a translucent brown groundmass. Microprobe analyses show some variability in the chondritic olivine and pyroxene compositions; olivine, Fa23-Fa26, average Fa24; pyroxene, Fs10-Fs19, average Fs16. Olivine and pyroxene in the two granular enclaves have essentially identical and uniform composition, Fa24, but the pyroxene is somewhat variable, Fs13-Fs21, average Fs17. The meteorite is classified as an L3 chondrite with enclaves.

Data from:
  MB76
  Table 2
  Line 172:
Origin or pseudonym:Main icefield
Mass (g):1470
Class:L3.7/3.9
Weathering grade:A/B
Fayalite (mol%):15-35
Ferrosilite (mol%):14-23
Comments:26Al=40±3; 77216 pairing group
Catalogs:
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Search for this meteorite in the NASA/JSC database (U.S.):   
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 38940 approved meteorites from Antarctica (plus 5051 unapproved names)
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