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Allan Hills A81021
Basic information Name: Allan Hills A81021
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA81021
This meteorite may also be called Allan Hills 81021 (ALH 81021) in publications.

Observed fall: No
Year found: 1981
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 695 g
Antarctic Meteorite Newsletter:  AMN 6(1)  (1983)  E6
AMN 17(1)  (1994)  EL6
Meteoritical Bulletin:  MB 76  (1994)  EL6
NHM Catalogue:  5th Edition  (2000)  EL6
MetBase:  v. 7.1  (2006)  EL6
Recommended:  EL6    [explanation]

This is 1 of 133 approved meteorites classified as EL6.   [show all]
Search for other: EL chondrites, Enstatite chondrites, Enstatite chondrites (type 4-7), and Enstatite-rich meteorites
Writeup from AMN 6(1):

Sample No.: ALHA81021

Location: Allan Hills

Field No.: 1424

Weight (gms): 695.1

Meteorite Type: E6 Chondrite


Physical Description: Carol Schwarz

Flow lines mark the broad top surface of this otherwise smooth and flat specimen. The bottom surface has weathered more extensively than the top. The interior that was exposed is extremely weathered. Dimensions: 12 x 9 x 3 cm.


Petrographic Description: Brian Mason

Only traces of chondritic structure are visible in the section, which consists largely of granular enstatite, with considerable nickel-iron (~20%), minor troilite and plagioclase, and accessory sinoite (Si2N2O, identified by its high birefringence). Weathering is extensive, with brown limonitic staining throughout the section. Remnants of fusion crust are present. Microprobe analyses show the enstatite is almost pure MgSiO3 (CaO 0.8%, FeO 0.2%, Al2O3 0.2%); plagioclase is An15Or4; the metal contains about 2% Si. The meteorite is an E6 chondrite.

Data from:
  Table 2
  Line 544:
Origin or pseudonym:Middle Western
Mass (g):695.1
Weathering grade:A
Ferrosilite (mol%):0-1
Comments:26Al=44±3; 81021 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' 51"S, 158° 13' 50"E)
Note: the NHM and MetBase coordinates are 38.8 km apart

     This is 1 of 44549 approved meteorites from Antarctica (plus 3803 unapproved names)
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