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Allan Hills A77224
Basic information Name: Allan Hills A77224
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77224
This meteorite may also be called Allan Hills 77224 (ALH 77224) in publications.

Observed fall: No
Year found: 1977 or 1978
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 787 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 1(3)  (1978)  H5
AMN 2(1)  (1979)  H4
AMN 3(2)  (1980)  H5
AMN 4(1)  (1981)  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 5782 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)
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.: ALHA77224

Location: Allan Hills

Field No.: 78012506

Weight (gms): 786.9

Meteorite Type: H4 Chondrite

 

Physical Description:

Specimen is angular, extremely weathered and friable. When meteorite was removed from cold storage and placed in the processing cabinet, many pieces fell off the main mass. There are many surface fissures that appear to continue throughout the meteorite. The B surface (not photographed) shows patches of fusion crust (very thin) and remnants of regmaglypts. The reddish-brown iron-oxide staining that is the prevalent color has an iridescent-like sheen on the B surface. The remaining exterior surfaces have small patches of a brownish-black fusion crust. Ice was observed in surface cracks when the specimen was removed from cold storage. This is not a complete specimen. The T surface appears to be a fracture surface. Small inclusions were observed on the weathered exterior surface. The T.S. and T.L. chips were taken from chips generated from sample when removed from cold storage. Approximate size : 13 x 14 cm.

 

Petrographic Description: Brian Mason

Chondritic structure is well-developed, with individual chondrules 0.2 - 1.0 mm in diameter; chondrule types include granular and porphyritic olivine, barred olivine, and fine-grained pyroxene. Minor amounts of troilite and nickel-iron are present, the nickel-iron being extensively weathered to limonite, which pervades the section. Black veining is prominent, the black color being partly due to fine-grained troilite. Microprobe analyses show olivine (Fa19) and orthopyroxene (Fs17) of essentially uniform composition.

Data from:
  MB76
  Table 2
  Line 180:
Origin or pseudonym:Near Western
Mass (g):786.9
Class:H4
Weathering grade:C
Fayalite (mol%):19
Ferrosilite (mol%):17
Comments:26Al=59±2; 77004 pairing group
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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