Sample Petrographic Description
Sample Number | EET 87532 |
Newsletter | 11,2 |
Location | Elephant Moraine |
Field Number | 2631 |
Dimensions (cm) | 9.0 x 4.0 x 4.0 |
Weight (g) | 193.50 |
Original Classification | Eucrite |
Updated Classification | Howardite |
Pairing | EET 87509; EET 83376; EET 87510; EET 87518; EET 87531; EET 87532; EET 92022; EET 99400; EET 99408; |
Mineral Composition (%Fa & %Fs) | |
Ferrosilite (mol%): 33-55 | |
Weathering | |
B/C | |
Fracturing | |
B | |
Macroscopic Description - René Martinez | |
This eucrite is heavily weathered. A few dark fine-grained clasts are visible up to about 1 cm across. One coarse-grained monomineralic inclusion is about 2 cm in length. The matrix is fine-grained and dark-gray with a 0.5 cm thick weathering rind. | |
Thin Section Description (,8) - Brian Mason | |
The section shows a microbreccia, consisting largely of angular monomineralic pyroxene and plagioclase clasts up to 1.2 cm in maximum dimension, and a few lithic clasts, in a matrix of comminuted pyroxene and plagioclase. Clasts show basaltic to subophitic texture, except for one (6 mm across), which consists of large (up to 2.5 mm) rounded subhedral pyroxene (Wo7Fs33) grains in turbid brown glass. Microprobe analyses show pyroxene of variable composition: Wo2-40, Fs33-55, En14-60; plagioclase is An91-93. The meteorite is a polymict eucrite. | |
Reclassification Notes (AMN 45,2) | |
Based on data presented by Mittlefehldt et al. (2013) EET 87532 is a howardite, not a polymict eucrite, and has been paired with the EET 87509 pairing group. | |
Notes | |
An initially defined pairing group (e.g., AMN 11, 2) consisting of EET 87503, EET 87509, EET 87510, EET 87512, EET 87518, and EET 87531 has been re-evaluated by Mittlefehldt et al. (2013). Based on petrography, mineralogy, petrology, bulk composition, and find locations, EET 87503 was removed from this group (and instead paired with EET 87513), and EET 87512 was removed from this group to be unpaired. The original group also gained EET 92002, EET 83376 (previously unpaired), EET 87532 (previously unpaired), and two from 1999 field season EET 99400 and EET 99408. Thus, the newly revised pairing groups are EET 87503 (503 and 513) and EET 87509 (EET 87509, EET 87510, EET 87518, and EET 87531, EET 87532, EET 83376, EET 92022, EET 99400 and EET 99408). EET 87512 is unpaired. |
Antarctic Meteorite Images for Sample EET 87532 | ||||
Lab Photo(s) : | ||||
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Antarctic Meteorite Images for Sample EET 87532 | ||||
Thin Section Photo(s) : | ||||
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References for Sample EET87532 | |
Dyar, M.D., Wallace, S.M., Burbine, T.H., and Sheldon, D.R., 2023, A machine learning classification of meteorite spectra applied to understanding asteroids. Icarus, 406, 115718, https://doi.org/10.1016/j.icarus.2023.115718. | |
Moriarty, D. P., Pieters, C. M., 2016, Complexities in pyroxene compositions derived from absorption band centers: Examples from Apollo samples, HED meteorites, synthetic pure pyroxenes, and remote sensing data. Meteoritics & Planetary Science, 51(2), 207-234. | |
Mittlefehldt, D. W., 2015, Asteroid (4) Vesta: I. The howardite-eucrite-diogenite (HED) clan of meteorites. Chemie der Erde - Geochemistry, 75 Issue 2, Jun-15, 155-183, ISSN 0009-2819, http://dx.doi.org/10.1016/j.chemer.2014.08.002. | |
Mittlefehldt, D. W., Herrin, J. S., Quinn, J. E., Mertzman, S. A., Cartwright, J. A., Mertzman, K. R., Peng, Z. X., 2013, Composition and petrology of HED polymict breccias: The regolith of (4) Vesta. Meteoritics & Planetary Science, 48, 2105-2134, http://dx.doi.org/10.1111/maps.12182. | |
Singerling, S. A., Mcsween, H. Y., Taylor, L. A., 2013, Glasses in howardites: Impact melts or pyroclasts?. Meteoritics & Planetary Science, 48, 715-729, http://dx.doi.org/10.1111/maps.12099. | |
Sears, D. W. G., Benoit, P. H., Sears, H., Batchelor, J. D., Symes, S., 1991, The natural thermoluminescence of meteorites: III. lunar and basaltic meteorites. Geochimica et Cosmochimica Acta, 55 Issue 11, Nov-91, 3167-3180, ISSN 0016-7037, http://dx.doi.org/10.1016/0016-7037(91)90481-J. | |
RELAB, , Reflectance Experiment Lab , catalogue of samples. |