Sample Petrographic Description
Sample Number | ALH 82131 |
Newsletter | 7,2 |
Location | Allan Hills |
Field Number | 2913 |
Dimensions (cm) | 1.0 x 1.0 x 0.5 |
Weight (g) | 0.97 |
Original Classification | C2 Chondrite |
Updated Classification | CM2 Chondrite |
Pairing | ALH 82100; ALH 82131; ALH 84036; ALH 84039; ALH 84046; ALH 84050; ALH 84053; ALH 90407; ALH 99500; |
Mineral Composition (%Fa & %Fs) | |
Fayalite (mol%): 0.3 | |
Weathering | |
A | |
Fracturing | |
B | |
Macroscopic Description - Roberta Score | |
One small patch of blistery fusion crust remains on this small meteorite fragment. The color of the exterior surfaces is black with a greenish tinge. The interior matrix is black and contains many submillimeter sized white inclusions. A green colored weathering rind extends approximately 1 mm into the interior of the stone. | |
Thin Section Description (,2) - Brian Mason | |
The very small section shows a single chondrule in black opaque matrix. Microprobe analyses show that the matrix has the composition characteristic of C2 chondrites. Olivine in the chondrule is almost pure forsterite (FeO, 0.3%; CaO, 0.3-0.4%). The meteorite is a C2 chondrite. | |
Reclassification Notes (AMN 17,1) | |
Many carbonaceous chondrites were initially classified as C2 in early newsletters. These are mostly CM2, based on matrix properties, chondrules abundance and sizes, and therefore all these samples have been reclassified more specifically here as CM2. | |
Notes | |
ALH 82100, ALH 82131, and ALH 84036, ALH 84039, ALH 84046, ALH 84050, ALH 84053, ALH 90407, and ALH 99500 are all from the far western icefield; although they have been paired for many years with ALH 81002, the latter is nearly 80 km away and too far to be reasonably paired given the ice flow regimes in that region. Additionally, available observations suggest ALH 99500 was erroneously paired with ALH 83100 - instead we suggest pairing with ALH 82100. AMN 45 no. 2. |
Antarctic Meteorite Images for Sample ALH 82131 | ||||
Lab Photo(s) : | ||||
Antarctic Meteorite Images for Sample ALH 82131 | ||||
Thin Section Photo(s) : | ||||
References for Sample ALH82131 | |
Benoit, P. H., Sears, D. W. G., Akridge, J. M. C., Bland, P. A., Berry, F. J., Pillinger, C. T., 2000, The non-trivial problem of meteorite pairing. Meteoritics & Planetary Science, 35, 393-417. | |
Marvin, U. B., MacPherson, G. J., 1989, Field and Laboratory Investigations of Meteorites from Victoria Land and the Thiel Mountains Region, Antarctica 1982-1983 and 1983-1984. Smithsonian Contributions to the Earth Sciences Number, 28, 146. | |
Scott, E. R. D., 1984, Pairing of meteorites found in Victoria Land, Antarctica. Memoirs of National Institute of Polar Research., Special issue 35, 102-125, http://ci.nii.ac.jp/naid/110000009967/en/. |