|Allan Hills A81059|
|Basic information||Name: Allan Hills A81059|
This is an OFFICIAL meteorite name.
This meteorite may also be called Allan Hills 81059 (ALH 81059) in publications.
Observed fall: No
Year found: 1981
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass: 540 g
This is 1 of 4 approved meteorites classified as Mesosiderite-B1. [show all]
Search for other: Class B mesosiderites, Metal-rich meteorites, and Mesosiderites
Writeup from AMN 6(1):
Sample No.: ALHA81059
Location: Allan Hills
Field No.: 1282
Weight (gms): 539.5
Meteorite Type: Mesosiderite
Physical Description: Roberta Score
The exterior of this mesosiderite has many greenish pyroxene grains, which all show cleavage faces. Several of the larger ones (up to 1.5 x 1 cm) can easily be removed. The stone appears to be fairly weathered with many fractures criss-crossing the exterior. A few small patches of fusion crust remain. Weathering of the interior is extensive. Dimensions: 9.5 x 5 x 5.5 cm.
Petrographic Description: Brian Mason
The section consists largely of orthopyroxene clasts ranging up to 10 mm in maximum dimensions, together with about 30% of nickel-iron in grains up to 0.6 mm; a little troilite is present. The meteorite is extremely weathered and seamed with brown limonite. Microprobe analyses shows that the orthopyroxene is somewhat variable in composition, ranging from Fs25 to Fs32, with a mean of Fs28; mean weight per cent CaO is 1.2, MnO 0.7, A12O3 0.6, TiO2 0.2. Small amounts of olivine (Fa28), plagioclase (An93), merrillite, and an SiO2 phase (probably tridymite) were detected with the microprobe. The meteorite is a mesosiderite, the second from the Allan Hills. It appears to be different from the previous one, ALHA77219.
|References:||Published in Antarctic Meteorite Newsletter 6(1) (1983), JSC, Houston|
Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
This is 1 of 36008 approved meteorites from Antarctica (plus 5519 unapproved names)
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