Sample Petrographic Description
Sample Number | ALH 81260 |
Newsletter | 8,1 |
Location | Allan Hills |
Field Number | 1432 |
Dimensions (cm) | 4.5 x 5.0 x 3.0 |
Weight (g) | 124.10 |
Original Classification | E6 Chondrite |
Updated Classification | EL6 Chondrite |
Pairing | ALH 81021; ALH 81260; ALH 83018; |
Mineral Composition (%Fa & %Fs) | |
Ferrosilite (mol%): 0.3 | |
Weathering | |
A/Be | |
Fracturing | |
A/B | |
Macroscopic Description - Roberta Score | |
Weathered fusion crust covers approximately 80% of this meteorite fragment. The one fracture surface has a deep reddish-brown color. Evaporite deposit is abundant immediately beneath the fusion crust and occurs in minute quantities on the exterior surfaces. The stone is extremely hard to break. The interior matrix has an overall bluish-black color. Under the binocular microscope crystal faces are visible. | |
Thin Section Description (,3) - Brian Mason | |
Only vague traces of chondritic structure are visible in the section which consists largely of granular enstatite, with considerable nickel-iron (approximately 20%) and minor amounts of sulfides and plagioclase. Remnants of fusion crust are present. Weathering is minor, with a little limonitic staining around some metal grains. Microprobe analyses show the enstatite is almost pure MgSiO3 (CaO 0.8%, FeO 0.2%, Al2O3, TiO2, MnO 0.1%); plagioclase is somewhat variable in composition, An13-19. The meteorite is an E6 chondrite; the only other E6 chondrite from the Allan Hills, ALHA81021, is similar but appears to be more weathered. The possibility of pairing should be considered | |
Reclassification Notes (AMN 17,1) | |
Re-classified based on information presented by Keil, K., 1989, Enstatite meteorites and their parent bodies, Meteoritics, 24, 195-208. |
Antarctic Meteorite Images for Sample ALH 81260 | ||||
Thin Section Photo(s) : | ||||
References for Sample ALH81260 | |
Greenwood, R. C., Franchi, I. A., Gibson, J. M., Benedix, G. K., 2012, Oxygen isotope variation in primitive achondrites: The influence of primordial, asteroidal and terrestrial processes. Geochimica et Cosmochimica Acta, 94, 1-Oct-12, 146-163, ISSN 0016-7037, http://dx.doi.org/10.1016/j.gca.2012.06.025. | |
Schultz, L., Franke, L., 2004, Helium, neon, and argon in meteorites: A data collection. Meteoritics & Planetary Science, 39, 1889-1890, http://dx.doi.org/10.1111/j.1945-5100.2004.tb00083.x. | |
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. | |
Keil, K., 1989, Enstatite meteorites and their parent bodies. Meteoritics, 24, 195-208. | |
Kallemeyn, G. W., Wasson, J. T., 1986, Compositions of enstatite (EH3, EH4,5 and EL6) chondrites: Implications regarding their formation. Geochimica et Cosmochimica Acta, 50 Issue 10, Oct-86, 2153-2164, ISSN 0016-7037, http://dx.doi.org/10.1016/0016-7037(86)90070-0. |