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Allan Hills A77255
Basic information Name: Allan Hills A77255
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77255
This meteorite may also be called Allan Hills 77255 (ALH 77255) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 765 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 2(1)  (1979)  Iron
AMN 4(1)  (1981)  Iron-ataxite-an
AMN 13(1)  (1990)  Iron-ataxite-ung
Meteoritical Bulletin:  MB 76  (1994)  Iron-ung
NHM Catalogue:  5th Edition  (2000)  Iron-ung
MetBase:  v. 7.1  (2006)  Iron-ung
Recommended:  Iron, ungrouped    [explanation]

This is 1 of 116 approved meteorites (plus 1 unapproved name) classified as Iron, ungrouped.   [show all]
Search for other: Metal-rich meteorites, Ungrouped irons, 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.: ALHA77255

Location: Allan Hills

Field No.: 77122929

Weight (gms): 765.1

Meteorite Type: Iron - unclassified

 

Physical Description:

This sample is shaped like a boomerang and is approximately 15.5x7.0x1.5 cm. The two flat surfaces, B and T, have an iridescent goldish-red sheen on the brownish-black fusion crust. The B surface is darker brownish-red than the other surfaces and is concave. Small regmaglypts, ~1 mm or less in depth, are present on the N and T surfaces. All corners on the specimen are smooth and rounded.

 

Tentative Description: Roy S. Clarke, Jr.

Approximately 10 cm2 of macroetched surface and 20 cm2 of sawn surface were examined. The etch pattern is uniform, indistinct, fine, and free of inclusions.' The complete rim of the specimen has been altered by atmospheric ablation. The saw cut that removed the slice from the main mass passed through the edge of a spherical silicate (?) inclusion approximately 5 mm in diameter. Most of this inclusion remains within the butt. Several small inclusions that appear to be sulfides are present on this sawn surface. External weathering appears to have been moderate. This is an unusual meteorite, and insufficient information is available at this time for even a tentative classification.


[Addendum to AMN 4(1)]

ALHA77255

This meteorite is an anomalous ataxite containing 12.2% Ni. It is similar in composition and structure to the Nordheim meteorite (R. S. Clarke, Jr.).

Data from:
  MB76
  Table 2
  Line 206:
Origin or pseudonym:Near Western
Mass (g):765.1
Class:Iron ung
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 33933 approved meteorites from Antarctica (plus 6798 unapproved names)
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