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Allan Hills A77250
Basic information Name: Allan Hills A77250
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77250
This meteorite may also be called Allan Hills 77250 (ALH 77250) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 10.56 kg
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 1(3)  (1978)  Iron
AMN 3(2)  (1980)  Iron-Group I or Og
AMN 7(1)  (1984)  IA
Meteoritical Bulletin:  MB 76  (1994)  IA
NHM Catalogue:  5th Edition  (2000)  IAB
NIPR Catalogue:  2000 Edition  (2000)  IA-coarse octahedrite
MetBase:  v. 7.1  (2006)  IAB-MG
Recommended:  Iron, IAB-MG    [explanation]

This is 1 of 85 approved meteorites classified as Iron, IAB-MG.   [show all]
Search for other: IAB complex irons, Metal-rich meteorites, and Iron meteorites
Writeuphelp
Writeup from AMN 3(2):
This text was reprinted from AMN 3(2) in AMN 4(1). In some cases, it may be an updated version from the original.

Sample No.: ALHA77250

Location: Allan Hills

Field No.: 77122930

Weight (gms): 10.555 kg

Meteorite Type: Iron - Group I or Og

 

Physical Description:

The overall color of the specimen is reddish-brown to brown with some areas of golden brown. The specimen is tabular with angular peaks on the T surface which form a ridge. There are numerous regmaglypts on all surfaces. Rounded holes ~1-2 cm deep were noted on the S surface. Dark gray material lines the bottom of some of these depressions. Golden-brown squama-like patches appear randomly over the entire meteorite, one larger patch ~2 cm x 1 cm appears on the B surface. Ice was preserved on this sample when it was removed from the freezer. Approximate dimensions: 27 x 13 x 11 cm.

 

Tentative Classification: Roy S. Clarke Jr.

An area of approximately 60 cm of macroetched surface was examined. Kamacite band widths are in the 2.5 to 3.5 mm range, with a length to width ratio of about 4. Neumann bands are present, and the rim of the slice contains several areas that have been converted to a α2 by atmospheric ablation. Patches of recrystallized kamacite occur throughout the slice. Taenite is present along kamacite grain boundaries and some area of comb plessite were observed. One large troilite and one large troilite-carbon inclusion are present. These inclusions are surrounded by schreibersite which in turn is surrounded by cohenite. Schreibersite is also present as a grain boundary precipitate. External weathering is uniform and moderately severe. The specimen is a coarse octahedrite, a typical Group I or Og meteorite.

Data from:
  MB76
  Table 2
  Line 201:
Origin or pseudonym:Main icefield
Mass (g):10555
Class:IA
Comments:76002 pairing group
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 3(2) (1980), 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 33930 approved meteorites from Antarctica (plus 6798 unapproved names)
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