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Allan Hills A77001
Basic information Name: Allan Hills A77001
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77001
This meteorite may also be called Allan Hills 77001 (ALH 77001) in publications.

Observed fall: No
Year found: 1977 or 1978
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 252 g
Antarctic Meteorite Newsletter:  AMN 1(1)  (1978)  L6
Meteoritical Bulletin:  MB 76  (1994)  L6
NHM Catalogue:  5th Edition  (2000)  L6
NIPR Catalogue:  2000 Edition  (2000)  L6
MetBase:  v. 7.1  (2006)  L6
Recommended:  L6    [explanation]

This is 1 of 12206 approved meteorites (plus 7 unapproved names) classified as L6.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeup from AMN 4(1):

Sample No.: ALHA77001

Location: Allan Hills

Field No.: 78010210A

Weight (gms): 252.0

Meteorite Type: L6 Chondrite


Physical Description:

Fusion crust is mainly missing. One large surface was produced by breaking after fall; complementary fragment is probably in the collection. Original surfaces are considerably weathered. Sawed surface showed unweathered metal particles to within ~1 cm of the surface. Specimen contains several cracks and appears slightly friable. One existing broken surface contained an irregular, medium gray, fine grained clast ~0.7 cm across. No clasts were noted on the sawed face.


Petrographic Description: Brian Mason

Antarctic meteorite ALHA77001 is a typical L6 chondrite. Chondrules are sparse and poorly defined; maximum diameter is 1.9 mm. Major minerals are olivine (Fa25) and orthopyroxene (Wo1.7En77Fs21). About 10% of plagioclase (Ab83An11Or6) is present as untwinned birefringent grains up to 0.15 mm across. Minor phases are nickel-iron (≈8%), troilite (~6%), diopside (~4%), chromite (<1%) and merrillite (<1%). The small section examined shows no signs of shock or veining. A moderate amount of limonitic staining is present around most nickel-iron grains, none around troilite.

Data from:
  Table 2
  Line 10:
Origin or pseudonym:Main icefield
Mass (g):252
Weathering grade:B
Fayalite (mol%):25
Ferrosilite (mol%):21
Comments:26Al=52±5; 77001 pairing group
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References: Published in Antarctic Meteorite Newsletter 4(1) (1981), JSC, Houston
Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
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     Catalogue of Meteorites:   (76° 43'S, 159° 40'E)
     Recommended::   (76° 45'S, 159° 20'E)
Note: the NHM and MetBase coordinates are 9.3 km apart

     This is 1 of 43700 approved meteorites from Antarctica (plus 3802 unapproved names)
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