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Allan Hills A77230
Basic information Name: Allan Hills A77230
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77230
This meteorite may also be called Allan Hills 77230 (ALH 77230) in publications.

Observed fall: No
Year found: 1977
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 2.47 kg
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 1(3)  (1978)  L4
Meteoritical Bulletin:  MB 76  (1994)  L4
NHM Catalogue:  5th Edition  (2000)  L4
NIPR Catalogue:  2000 Edition  (2000)  L4
MetBase:  v. 7.1  (2006)  L4
Recommended:  L4    [explanation]

This is 1 of 1617 approved meteorites (plus 4 unapproved names) classified as L4.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeuphelp
Writeup from AMN 1(3):
This text was reprinted from AMN 1(3) in AMN 4(1). In some cases, it may be an updated version from the original.

Sample No.: ALHA77230

Location: Allan Hills

Field No.: 77122703

Weight (gms): 2473.3

Meteorite Type: L4 Chondrite

 

Physical Description:

This is a subrounded to angular specimen which is nearly a complete stone. A brownish-black fusion crust, approximately .5 to 1 mm thick, covers the specimen, with the exception of small broken surfaces. The portion of the fusion crust that was in contact with the ice has an iridescent-like sheen. The specimen has several surface fissures. The specimen was difficult to chip for thin section material. Snow was present along fissures on the interior of the stone. The surface of the meteorite that was in contact with the ice was more severely weathered than the uppermost portion. Weathering is along fissures to a depth of ~5 mm.

 

Petrographic Description: Brian Mason

The section shows a closely-packed aggregate of chondrules, some spherical, but many appear fragmented and broken. A variety of chondrule types are present: barred olivine, porphyritic olivine, fine-grained pyroxene, etc. Chondrule size ranges from 0.3 to 1.0 mm; interstitial material in some chondrules is turbid devitrified glass. Some pyroxene shows polysynthetic twinning. Minor subequal amounts of troilite and nickel-iron are present. A moderate amount of limonitic staining pervades the section. Fusion crust is present on one edge. Microprobe analyses show olivine of fairly uniform composition (Fa22-Fa25, average Fa23) and pyroxene averaging Fs21.

Data from:
  MB76
  Table 2
  Line 185:
Origin or pseudonym:Main icefield
Mass (g):2473
Class:L4
Weathering grade:C
Fayalite (mol%):22-25
Ferrosilite (mol%):18-29
Comments:26Al=51±3
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 1(3) (1978), 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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