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Allan Hills A77012
Basic information Name: Allan Hills A77012
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77012
This meteorite may also be called Allan Hills 77012 (ALH 77012) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 180.2 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 3(1)  (1980)  H5
Meteoritical Bulletin:  MB 76  (1994)  H5
NHM Catalogue:  5th Edition  (2000)  H5
NIPR Catalogue:  2000 Edition  (2000)  H5
MetBase:  v. 7.1  (2006)  H5
Recommended:  H5    [explanation]

This is 1 of 9646 approved meteorites (plus 16 unapproved names) classified as H5.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeuphelp
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.: ALHA77012

Location: Allan Hills

Field No.: 77122942

Weight (gms): 180.2

Meteorite Type: H5 Chondrite

 

Physical Description:

The sample is roughly pyramidal in shape, with the E surface being semi-flat and a fracture surface. The B and S surfaces have very thin, patchy, black fusion crust. The remainder of the sample is stained reddish-brown by iron oxidation. No unweathered material was exposed during processing.

 

Petrographic Description: Brian Mason

Chondritic structure is well developed; chondrules are 0.3-0.9 mm in diameter, the commonest types being granular olivine, barred olivine, and fine-grained pyroxene. In the olivine chondrules the material interstitial to the olivine is a fine-grained aggregate probably of pyroxene and plagioclase. Some larger irregular aggregates of granular olivine (up to 6 mm in greatest dimension) are present. The matrix of the chondrules and aggregates is a granular aggregate of olivine pyroxene, with minor nickel-iron and troilite (nickel-iron in excess of troilite). Somewhat eroded fusion crust is present along one edge. The section is pervaded with brown limonitic staining, and small patches and veinlets of limonite are present. Microprobe analyses show uniform olivine (Fa18) and orthopyroxene (Fs16) compositions. The meteorite is classified as an H5 chondrite.

Data from:
  MB76
  Table 2
  Line 20:
Origin or pseudonym:Main icefield
Mass (g):180.2
Class:H5
Weathering grade:Ce
Fayalite (mol%):18
Ferrosilite (mol%):16
Comments:26Al=78±3
Catalogs:
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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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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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