Sample Petrographic Description
Sample Number | ALH 84023 |
Newsletter | 9,2 |
Location | Allan Hills |
Field Number | 2869 |
Dimensions (cm) | 6.0 x 4.0 x 5.0 |
Weight (g) | 262.40 |
Original Classification | Aubrite |
Pairing | ALH 83009; ALH 83015; ALH 84007; ALH 84008; ALH 84009; ALH 84010; ALH 84011; ALH 84012; ALH 84013; ALH 84014; ALH 84015; ALH 84016; ALH 84017; ALH 84018; ALH 84019; ALH 84020; ALH 84021; ALH 84023; ALH 84024; |
Mineral Composition (%Fa & %Fs) | |
Fayalite (mol%): 0;Ferrosilite (mol%): 0 | |
Weathering | |
A | |
Fracturing | |
A | |
Macroscopic Description - René Martinez | |
Most of these aubrites have thin patchy brown to yellow fusion crust. All specimens are slightly weathered. Enstatite clasts are as large as 3.5 cm and as small as 1 mm. The clast population ranges from sparse to dense for the different specimens. Dark aphanitic inclusions and metallic inclusions surrounded by oxidation haloes are both common. | |
Thin Section Description - Brian Mason | |
Polished thin sections of these specimens show that they are aubrites, and can confidently be paired with ALH 84007, 008, and 011 (described in Antarctic Meteorite Newsletter 8(2), and probably with ALH 83009 and 015, collected in the same area (Middle Western Icefield). They consist almost entirely of iron-free enstatite, with rare plagioclase (An7-10), forsterite (usually iron-free, but up to Fa9), and iron-free diopside (Wo42). Small amounts of opaque minerals are present; these include troilite, oldhamite, alabandite, daubreelite, and nickel-iron. Visual inspection of chips of ALH 84014, 015, 018, 019, 020, 021, and 022 show that these are also aubrites, probably pieces of the same meteorite. |
Antarctic Meteorite Images for Sample ALH 84023 | ||||
Lab Photo(s) : | ||||
Antarctic Meteorite Images for Sample ALH 84023 | ||||
Thin Section Photo(s) : | ||||
References for Sample ALH84023 | |
Keil, K., 2010, Enstatite achondrite meteorites (aubrites) and the histories of their asteroidal parent bodies. Chemie der Erde - Geochemistry, 70 Issue 4, 2010, 295-317, ISSN 0009-2819, http://dx.doi.org/10.1016/j.chemer.2010.02.002. | |
Rai, V. K., Jackson, T. L., Thiemens, M. H., 2005, Photochemical Mass-Independent Sulfur Isotopes in Achondritic Meteorites. Science, 309, 1062-1065, http://dx.doi.org/10.1126/science.1112954. | |
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. | |
Casanova, I., Keil, K., Newsom, H. E., 1993, Composition of metal in aubrites: Constraints on core formation. Geochimica et Cosmochimica Acta, 57 Issue 3, Feb-93, 675-682, ISSN 0016-7037, http://dx.doi.org/10.1016/0016-7037(93)90377-9. | |
Marvin, U. B., MacPherson, G. J., 1992, Field and Laboratory Investigations of Antarctica Meteorites Collected by United States Expeditions, Smithsonian Contributions to the Earth Sciences Number, 30, 116. |