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Allan Hills A77003
Basic information Name: Allan Hills A77003
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77003
This meteorite may also be called Allan Hills 77003 (ALH 77003) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 780 g
Antarctic Meteorite Newsletter:  AMN 1(2)  (1978)  L3
AMN 4(1)  (1981)  H3
AMN 7(1)  (1984)  CO3
Meteoritical Bulletin:  MB 76  (1994)  CO3
NHM Catalogue:  5th Edition  (2000)  CO3.5
NIPR Catalogue:  2000 Edition  (2000)  CO3
MetBase:  v. 7.1  (2006)  CO3.6
Antarctic Meteorite Newsletter:  AMN 31(1)  (2008)  CO3.6
Recommended:  CO3.6    [explanation]

This is 1 of 8 approved meteorites classified as CO3.6.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 3), CM-CO clan chondrites, and CO chondrites
Writeup from AMN 4(1):

Sample No.: ALHA77003

Location: Allan Hills

Field No.: 77122920

Weight (gms): 779.6

Meteorite Type: H3 Chondrite


Physical Description:

Specimen is very well rounded. No surface fissures are present. Fusion crust covers 33% of the meteorite's surface, (~100% T surface, 30% N and W surfaces, and 10% of E surface) and ranges from 1 to 3 mm thick. The crust is medium black and slightly glassy. The fusion crust is preserved on the surface (s) that were uppermost at the time of discovery (see field photo). The remaining surface of the meteorite is smooth, brownish-black, and has little iron-oxide staining. This surface is polished and may be the lower part of a fusion crust or a wind-polished surface. In an area ~l cm x 2 cm this surface has been removed, revealing an interior surface that is partially iron-oxide stained. This is a well indurated specimen. Repeated attempts to chip this meteorite for thin section samples were all partially successful.


Petrographic Description: Brian Mason

Numerous and well-defined chondrules, 0.1-0.6 mm in diameter, along with mineral clasts are present in a fine-grained groundmass colored brown with limonitic material. The chondrules exhibit a variety of form and structure, the commonest consisting of granular aggregates of olivine and polysynthetically twinned clinopyroxene; some chondrules have pale brown transparent glass interstitial to the olivine and pyroxene grains. Microprobe analyses show that both olivine and pyroxene are highly variable in composition. Olivine ranges from Fa4 to Fa48 with a mean of Fa22; pyroxene ranges from Fs2 to Fs25, with a mean of Fs14, and its calcium content averages 1% CaO. The highly variable composition of olivine and pyroxene indicates a type 3 chondrite, and the mean composition of the olivine and small amount of nickel-iron suggest L group, so the meteorite is tentatively classified L3; however, certain assignment of group should await further investigation.

Data from:
  Table 2
  Line 12:
Origin or pseudonym:Near Western
Mass (g):779.6
Weathering grade:Ae
Fayalite (mol%):4-48
Ferrosilite (mol%):2-25
Comments:26Al=45±5; 77003 pairing group
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References: Published in Antarctic Meteorite Newsletter 4(1) (1981), JSC, Houston
Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
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     Catalogue of Meteorites:   (76° 43'S, 159° 40'E)
     Recommended::   (76° 43'S, 159° 40'E)

     This is 1 of 43856 approved meteorites from Antarctica (plus 3802 unapproved names)
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