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Allan Hills 84200
Basic information Name: Allan Hills 84200
     This is an OFFICIAL meteorite name.
Abbreviation: ALH 84200
Observed fall: No
Year found: 1984
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 8.5 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 11(1)  (1988)  E4
Meteoritical Bulletin:  MB 76  (1994)  EH3
NHM Catalogue:  5th Edition  (2000)  EH3
MetBase:  v. 7.1  (2006)  EH3
Recommended:  EH3    [explanation]

This is 1 of 137 approved meteorites classified as EH3.   [show all]
Search for other: EH chondrites, Enstatite chondrites, Enstatite chondrites (type 3), and Enstatite-rich meteorites
Writeuphelp
Writeup from AMN 11(1):

Sample No.: ALH84200; 84220; 84235

Location: Allan Hills

Weight (g): 8.5; 8.4; 6.0

Field No.: 2538;2504;2378

Dimensions (cm): 3x1x1; 2x1.5x1.5; 2x2x0.8

Meteorite Type: E4 Chondrite

 

Macroscopic Description: Roberta Score

Very little fusion crust remains on these fragments. Part of ALH84200 is extensively oxidized and crumbles easily when handled. Other areas are black and contain inclusions that are <1 mm in size. ALH84220 and 84235 are extremely weathered; no features are visible.

 

Thin Section (ALH84200,2; 84220,2; 84235,2) Description: Brian Mason

These meteorites are identical in all respects and are probably paired. Chondrules and chondrule fragments are abundant, but are usually small (ranging up to 0.6 mm across, although a few are larger); they consist of fine-grained to coarsely granular pyroxene. The matrix consists of small pyroxene grains and opaque material (mostly nickel-iron with some sulfides). The meteorites are considerably weathered, with brown limonitic staining throughout the sections. Microprobe analyses show pyroxene compositions ranging from Fs0.6 to Fs4.0, with a mean of Fs1.8. The nickel-iron contains 2.3% Si. The meteorites are enstatite chondrites, and since most of the pyroxene is polysynthetically twinned clinoenstatite, they are classified E4. They closely resemble ALH84254, ALH82132, and some other ALH E4 chondrites, and the possibility of pairing should be considered.

Data from:
  MB76
  Table 2
  Line 1165:
Origin or pseudonym:Near Western
Mass (g):8.5
Class:EH3
Weathering grade:B
Ferrosilite (mol%):0.6-4
Comments:81189 pairing group
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 11(1) (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° 45' 26"S, 158° 47' 0"E)
Note: the NHM and MetBase coordinates are 23.1 km apart

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