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Allan Hills A77221
Basic information Name: Allan Hills A77221
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77221
This meteorite may also be called Allan Hills 77221 (ALH 77221) in publications.

Observed fall: No
Year found: 1977 or 1978
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 229 g
Antarctic Meteorite Newsletter:  AMN 3(1)  (1980)  H4
Meteoritical Bulletin:  MB 76  (1994)  H4
NHM Catalogue:  5th Edition  (2000)  H4
NIPR Catalogue:  2000 Edition  (2000)  H4
MetBase:  v. 7.1  (2006)  H4
Recommended:  H4    [explanation]

This is 1 of 6371 approved meteorites (plus 2 unapproved names) classified as H4.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeup from AMN 3(1):
This text was reprinted from AMN 3(1) in AMN 4(1). In some cases, it may be an updated version from the original.

Sample No.: ALHA77221

Location: Allan Hills

Field No.: 78012504

Weight (gms): 229.2

Meteorite Type: H4 Chondrite


Physical Description:

All surfaces of the meteorite, with the exception of the S surface, have remnant patches of thin, dull black fusion crust. The exterior surfaces devoid of fusion crust are stained by iron oxidation. Several clasts, approximately 1 mm in diameter, are apparent on the S surface. The specimen is fractured. Chipping revealed no unweathered material in the interior of the sample.


Petrographic Description: Brian Mason

Chondrules are numerous and well developed, and unusually large, ranging up to 3 mm in diameter; the commonest types are granular and barred olivine. One example of a chondrule within a chondrule (barred olivine) was noted. The groundmass consists of olivine and pyroxene, with a fair amount of nickel-iron in relatively large (up to 1.2 mm) grains, and a smaller amount of troilite. The groundmass is pervaded with fine-grained black material, probably carbonaceous. A little limonite is present. Microprobe analyses show olivine (Fa15) of essentially uniform composition and slightly variable pyroxene (Fs13-Fs15, average Fs14). The meteorite is classified as an H4 chondrite.

Data from:
  Table 2
  Line 177:
Origin or pseudonym:Near Western
Mass (g):229.2
Weathering grade:C
Fayalite (mol%):15
Ferrosilite (mol%):13-15
Comments:26Al=57±2; 77004 pairing group
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References: Published in Antarctic Meteorite Newsletter 3(1) (1980), 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 43499 approved meteorites from Antarctica (plus 3802 unapproved names)
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