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Allan Hills A81023
Basic information Name: Allan Hills A81023
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA81023
This meteorite may also be called Allan Hills 81023 (ALH 81023) in publications.

Observed fall: No
Year found: 1981
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 418 g
Antarctic Meteorite Newsletter:  AMN 6(1)  (1983)  L5
Meteoritical Bulletin:  MB 76  (1994)  L5
NHM Catalogue:  5th Edition  (2000)  L5
MetBase:  v. 7.1  (2006)  L5
Recommended:  L5    [explanation]

This is 1 of 8293 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 6(1):

Sample No.: ALHA81023

Location: Allan Hills

Field No.: 1427

Weight (gms): 418.3

Meteorite Type: L5 Chondrite

Physical Description: Roberta Score

ALHA81023 was found on the ice in Antarctica as 2 large pieces, 2 small pieces and many tiny chips. None of the pieces fit together, but are obviously related. The matrix is light gray with many dark colored chondrules, irregular shaped inclusions and troilite(?) grains that show relief from the exterior surface. Some fusion crust is present on each piece. Weathering is moderate. A minute amount of white deposit is present on one piece.

Petrographic Description: Brian Mason

Chondrules are abundant and well developed, ranging up to 2.3 mm across; a variety of types is present, including porphyritic olivine, granular olivine and olivine-pyroxene, and radiating pyroxene. They are set in a granular groundmass consisting largely of olivine and pyroxene with minor amounts of nickel-iron and troilite. Weathering is limited to brown limonitic staining around metal grains. Microprobe analyses give the following compositions: olivine, Fa25; orthopyroxene, Fs21. The meteorite is classified as an L5 chondrite; it is very similar to ALHA81017, 81018, and the possibility of pairing with these meteorites should be considered.

Data from:
  Table 2
  Line 546:
Origin or pseudonym:Middle Western
Mass (g):418.3
Weathering grade:B
Fayalite (mol%):25
Ferrosilite (mol%):21
Comments:26Al=36±1; 81018 pairing group
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References: Published in Antarctic Meteorite Newsletter 6(1) (1983), 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° 49' 48"S, 158° 13' 18"E)
Note: the NHM and MetBase coordinates are 39 km apart

     This is 1 of 43352 approved meteorites from Antarctica (plus 3802 unapproved names)
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