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Allan Hills A77285
Basic information Name: Allan Hills A77285
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77285
This meteorite may also be called Allan Hills 77285 (ALH 77285) in publications.

Observed fall: No
Year found: 1977 or 1978
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 271 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 2(1)  (1979)  H6
Meteoritical Bulletin:  MB 76  (1994)  H6
NHM Catalogue:  5th Edition  (2000)  H6
MetBase:  v. 7.1  (2006)  H6
Recommended:  H6    [explanation]

This is 1 of 5855 approved meteorites (plus 5 unapproved names) classified as H6.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeuphelp
Writeup from AMN 2(1):
This text was reprinted from AMN 2(1) in AMN 4(1). In some cases, it may be an updated version from the original.

Sample No.: ALHA77285

Location: Allan Hills

Field No.: Y78010510

Weight (gms): 271.1

Meteorite Type: H6 Chondrite

 

Physical Description:

This semi-rounded specimen is approximately 5.0x6.0x6.5 cm, the B and S surfaces are flat. The sample is made up of three individual pieces that fit together; one of these pieces was generated in transport. A small, less than 2 cm, patch of dull, black, fusion crust is present on the B surface. The exterior of the meteorite has a reddish-brown patina. All interior surfaces of the meteorite are weathered and range in color from orangish-brown to reddish-brown. No unweathered material was exposed while attempting to obtain suitable material for thin sections. Ice was present on the sample when it was removed from cold storage.

 

Petrographic Description: Brian Mason

The section shows sparse and poorly defined chondrules tending to merge with the granular groundmass, which consists largely of olivine and orthopyroxene, with minor amounts of nickel-iron, troilite in lesser quantity, and plagioclase. The meteorite is extensively weathered, with brown staining and veins and patches of limonite throughout the section. Microprobe analyses show olivine (Fa18), orthopyroxene (Fs16), and plagioclase (An12) of uniform composition. The meteorite is classified as an H6 chondrite.

Data from:
  MB76
  Table 2
  Line 235:
Origin or pseudonym:Main icefield
Mass (g):271.1
Class:H6
Weathering grade:C
Fayalite (mol%):18
Ferrosilite (mol%):16
Comments:26Al=38±4
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 2(1) (1979), 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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