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Allan Hills A81251 | |||||||||||||||||||||||||
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Basic information | Name: Allan Hills A81251 This is an OFFICIAL meteorite name. Abbreviation: ALHA81251 This meteorite may also be called Allan Hills 81251 (ALH 81251) in publications. Observed fall: No Year found: 1981 Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)] Mass: ![]() | ||||||||||||||||||||||||
Classification history: |
This is 1 of 15 approved meteorites classified as LL3.3. [show all] Search for other: LL chondrites, LL chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3) | ||||||||||||||||||||||||
Writeup![]() |
Writeup from AMN 6(1):
Sample No.: ALHA81251 Location: Allan Hills Field No.: 1248 Weight (gms): 158.0 Meteorite Type: LL3 Chondrite
Physical Description: Roberta Score Thin, black, shiny fusion crust covers half of this flat sample. The exterior appears to have been polished, and the broken surfaces show abundant chondrules as large as 0.5 cm in diameter. The interior exposed by chipping has weathered to a deep reddish-brown, obliterating any structure present. Dimensions: 6.5 x 6 x 2.5 cm.
Petrographic Description: Brian Mason The section shows a close-packed aggregate of chondrules and chondrule fragments, up to 3 mm in maximum dimension. Most of the matrix is black and opaque, with small grains of olivine and pyroxene; the black matrix appears to be carbonaceous, with small amounts of troilite and nickel-iron (largely weathered to limonite). A wide variety of chondrule types is present, including barred olivine, granular olivine and olivine-pyroxene, and fine-grained pyroxene. Clear glass is present in barred olivine chondrules. Microprobe analyses show olivine and pyroxene with variable compositions: olivine, Fa1-Fa29, mean Fa14 (per cent mean deviation FeO is 64); pyroxene, Fs2-Fs28 , mean Fs13 (per cent mean deviation FeO is 72). Clear glass in a barred olivine chondrule has the following composition (weight per cent): SiO2 61.4, Al2O3 23.5, FeO 1.7, MgO 2.0, CaO 0.4, Na2O 4.8, K2O 1.6, TiO2 1.1, MnO 0.01. The highly variable composition of olivine and pyroxene and the texture indicate Type 3. The small amount of nickel-iron suggests LL group. Hence the meteorite is tentatively classified as an LL3 chondrite. | ||||||||||||||||||||||||
Data from: MB76 Table 2 Line 773: |
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References: | Published in Antarctic Meteorite Newsletter 6(1) (1983), JSC, Houston Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
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Geography:![]() |
Statistics: This is 1 of 43700 approved meteorites from Antarctica (plus 3802 unapproved names) | ||||||||||||||||||||||||
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