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Allan Hills A81029
Basic information Name: Allan Hills A81029
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA81029
This meteorite may also be called Allan Hills 81029 (ALH 81029) in publications.

Observed fall: No
Year found: 1981
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 153 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 6(2)  (1983)  L6
Meteoritical Bulletin:  MB 76  (1994)  L6
NHM Catalogue:  5th Edition  (2000)  L6
MetBase:  v. 7.1  (2006)  L6
Recommended:  L6    [explanation]

This is 1 of 11277 approved meteorites (plus 6 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)
Writeuphelp
Writeup from AMN 6(2):

Sample No.: ALHA81029

Location: Allan Hills

Field No.: 1563

Weight (gms): 153.0

Meteorite Type: L6 Chondrite

Physical Description: Carol Schwarz

This specimen consists of two pieces which fit together. One surface has shiny black fusion crust while the others are weathered to an iridescent red brown. The interior is weathered. Dimensions: 9.5 x 5 x 2.5 cm

Petrographic Description: Brian Mason

Chondrules are sparse and poorly defined, tending to merge with the granular groundmass, which consists largely of olivine and pyroxene, with minor amounts of maskelynite, nickel-iron, and troilite. The meteorite is extensively weathered, the section being uniformly stained with brown limonite. Microprobe analyses gave the following compositions: olivine, Fa25 orthopyroxene, Fs21; the maskelynite has CaO (2.1%) appropriate to oligoclase composition, but Na2O is low and variable (3.2-4.1%). The meteorite is classified as an L6 chondrite. 

 

The section of ALHA81028 is similar in all respects; it has a veinlet up to 0.2 mm of fine-grained material which appears to consist largely of majorite and ringwoodite. ALHA81027 is similar, and these three meteorites are possibly paired.

Data from:
  MB76
  Table 2
  Line 552:
Origin or pseudonym:Main icefield
Mass (g):153
Class:L6
Weathering grade:C
Fayalite (mol%):25
Ferrosilite (mol%):21
Comments:26Al=39±2; 81027 pairing group
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 6(2) (1983), 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° 41' 23"S, 159° 16' 39"E)
Note: the NHM and MetBase coordinates are 10.4 km apart

Statistics:
     This is 1 of 40129 approved meteorites from Antarctica (plus 4494 unapproved names)
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