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Allan Hills A77002
Basic information Name: Allan Hills A77002
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77002
This meteorite may also be called Allan Hills 77002 (ALH 77002) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 235 g
Antarctic Meteorite Newsletter:  AMN 1(1)  (1978)  L5
Meteoritical Bulletin:  MB 76  (1994)  L5
NHM Catalogue:  5th Edition  (2000)  L5
NIPR Catalogue:  2000 Edition  (2000)  L5
MetBase:  v. 7.1  (2006)  L5
Recommended:  L5    [explanation]

This is 1 of 8504 approved meteorites (plus 4 unapproved names) classified as L5.   [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.: ALHA77002

Location: Allan Hills

Field No.: 77122927

Weight (gms): 235.2

Meteorite Type: L5 Chondrite


Physical Description:

Specimen reasonably angular with complete, brownish-black fusion crust which shows appreciable weathering. No broken surfaces to indicate crustal thickness. One large fracture. A few chipped corners show appreciable rusting. Specimen is approximately 6.5 x 4.5 cms in dimension.


Petrographic Description:

The meteorite is classified as an L5 chondrite. Chondrules are prominent and well-defined, 0.3-0.6 mm in diameter; most are porphyritic olivine, some fine-grained pyroxene. The matrix is dominantly olivine, in angular grains up to 1.0 mm in maximum dimension, with lesser amounts of orthopyroxene. Minor minerals in the matrix are nickel-iron, troilite, and chromite; plagioclase is present as very small grains difficult to recognize. The section is stained brown with limonitic materials and the metal grains are corroded evidently by terrestrial weathering, troilite is unaffected. Microprobe analyses show uniform composition in the olivine (Fa25) and orthopyroxene (Wo1.2 En77 Fs22), plagioclase composition averages Ab84An10 Or6, but appears somewhat variable.

Data from:
  Table 2
  Line 11:
Origin or pseudonym:Main icefield
Mass (g):235.2
Weathering grade:B
Fayalite (mol%):25
Ferrosilite (mol%):22
Comments:26Al=30±3; NTL=17.2±0.4
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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° 43'S, 159° 40'E)

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