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Allan Hills 85121
Basic information Name: Allan Hills 85121
     This is an OFFICIAL meteorite name.
Abbreviation: ALH 85121
Observed fall: No
Year found: 1985
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 55.3 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 11(2)  (1988)  H3
Meteoritical Bulletin:  MB 76  (1994)  H3.7
NHM Catalogue:  5th Edition  (2000)  H3.7
MetBase:  v. 7.1  (2006)  H3.7
Recommended:  H3.7    [explanation]

This is 1 of 75 approved meteorites classified as H3.7.   [show all]
Search for other: H chondrites, H chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
Writeuphelp
Writeup from AMN 11(2):

Sample No.: ALH85121

Location: Allan Hills

Weight (g): 55.3

Field No.: 2629

Dimensions (cm): 5 x 4 x 1

Meteorite Type: H3 Chondrite

 

Macroscopic Description: Roberta Score

Frothy brown and black fusion crust covers the T-surface of this mushroom-shaped stone while thick (2 mm) black ropy fusion crust covers the B surface. Numerous fractures penetrate the interior which is moderately to heavily weathered. A weathering rind that ranges in thickness from <1 mm to 5 mm is present. The matrix is medium gray in color with numerous clasts/chondrules visible.

 

Thin Section (,3) Description: Brian Mason

The section shows abundant chondrules and chondrule fragments, up to 3 mm across, in a matrix of fine-grained olivine and pyroxene with moderate amounts of nickel-iron and troilite (sometimes rimming chondrules). Chondrule types include granular and porphyritic olivine and olivine-pyroxene, and radiating or cryptocrystalline pyroxene. Weathering is extensive, with limonitic staining and small areas of red-brown limonite throughout the section. Microprobe analyses show olivine and pyroxene with a considerable range in composition: olivine, Fa9-20 (CV FeO is 16); pyroxene, Fs3-31. The content of nickel-iron suggests H group, and the variability of olivine and pyroxene compositions type 3, hence the meteorite is tentatively classified H3 (estimated H3.8).

Data from:
  MB76
  Table 2
  Line 1349:
Origin or pseudonym:Far Western
Mass (g):55.3
Class:H3.7
Weathering grade:B
Fayalite (mol%):9-20
Ferrosilite (mol%):3-31
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 11(2) (1988), 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° 50' 41"S, 156° 25' 45"E)
Note: the NHM and MetBase coordinates are 83.9 km apart

Statistics:
     This is 1 of 39179 approved meteorites from Antarctica (plus 5051 unapproved names)
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