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Allan Hills A77021
Basic information Name: Allan Hills A77021
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77021
This meteorite may also be called Allan Hills 77021 (ALH 77021) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 16.7 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 1(2)  (1978)  H5
Meteoritical Bulletin:  MB 76  (1994)  H5
NHM Catalogue:  5th Edition  (2000)  H5
NIPR Catalogue:  2000 Edition  (2000)  H5
MetBase:  v. 7.1  (2006)  H5
Recommended:  H5    [explanation]

This is 1 of 9649 approved meteorites (plus 16 unapproved names) classified as H5.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeuphelp
Writeup from AMN 4(1):

Sample No.: ALHA77021

Location: Allan Hills

Field No.: 77122744

Weight (gms): 16.65

Meteorite Type: H5 Chondrite

 

Physical Description:

A brownish-black fusion crust covers ~50% of the surface of specimen. The remaining surfaces are fracture surfaces which are severely weathered. The specimen was moderately difficult to chip. Chipping revealed an interior surface that is iron oxide stained.  Approximately 2.5 cm long.

 

Petrographic Description: Brian Mason

Chondritic structure well-developed; some chondrules are well-defined, others ark irregular in form and tend to merge-with the groundmass. Chondrules range from 0.3-1.0 mm in diameter, and show a variety of types: granular olivine and olivine-pyroxene, porphyritic olivine with interstitial partly-devitrified glass, barred; olivine, fine-grained pyroxene and others. Fusion crust is present. Yellow-brown limonitic staining is pervasive throughout the section, and some limonite veinlets are present. Microprobe analyses show olivine (Fa18) and orthopyroxene (Fs17) of uniform composition; some small grains of sodic plagioclase were detected.

Data from:
  MB76
  Table 2
  Line 28:
Origin or pseudonym:Main icefield
Mass (g):16.7
Class:H5
Weathering grade:C
Fayalite (mol%):18
Ferrosilite (mol%):17
Comments:26Al=63±8; 77021 pairing group
Catalogs:
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Search for this meteorite in the NASA/JSC database (U.S.):   
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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Geography:

Antarctica
Coordinates:
     Catalogue of Meteorites:   (76° 43'S, 159° 40'E)
     Recommended::   (76° 43'S, 159° 40'E)

Statistics:
     This is 1 of 39173 approved meteorites from Antarctica (plus 5051 unapproved names)
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