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| Northwest Africa 13355 | |||||||||||||||||||||||||||||
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| Basic information | Name: Northwest Africa 13355 This is an OFFICIAL meteorite name. Abbreviation: NWA 13355 Observed fall: No Year found: 2020 Country: (Northwest Africa) Mass:  672 g | ||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 15 approved meteorites classified as Eucrite-an. [show all] Search for other: Achondrites, Eucrites, and HED achondrites | ||||||||||||||||||||||||||||
| Comments: | Approved 19 Jul 2020 | ||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 109:
Northwest Africa 13355 (NWA 13355) (Northwest Africa) Purchased: 2020 May Classification: HED achondrite (Eucrite, anomalous) History: Purchased by Rachid Chaoui in May 2020 from a Mauritanian dealer. Physical characteristics: A very dark ellipsoidal specimen (672 g) partly coated by a shiny patina and with one broken side (slightly weathered). The fresh interior is dark gray with some larger dark crystals barely visible. Petrography: (A. Irving, UWS and P. Carpenter, WUSL) This specimen has an unbrecciated igneous texure, but is unique among eucrites in containing relatively large (up to 4 mm) subhedral phenocrysts of exsolved pigeonite with abundant thin exsolution lamellae of chromite. The prismatic phenocrysts are set in a groundmass of parallel-intergrown pigeonite and calcic plagioclase with accessory silica polymorph, Ti-chromite, ilmenite, troilite and baddeleyite. Geochemistry: Low-Ca pyroxene host (Fs49.6-53.2Wo1.8-3.0, FeO/MnO = 31-32, N = 4), augite exsolution lamellae (Fs23.1-25.0Wo39.6-42.7, FeO/MnO = 29-31, N = 2), plagioclase (An79.2-85.5Or6.5-0.6, N = 4). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed bulk subsamples by laser fluorination gave, respectively, δ17O 1.665, 1.895, 1.871; δ18O 3.693, 4.157, 4.105; Δ17O -0.285, -0.300, -0.296 per mil. These results plot beyond the main field for eucrites to more negative Δ17O values. Classification: Eucrite (unbrecciated, pyroxene-phyric, anomalous). The porphyritic igneous texture, prominent chromite exsolution in pyroxenes and atypical oxygen isotopic composition are anomalous features. Chromite exsolution from pyroxene has been documented in ungrouped achondrite GRA 06129 and some Luna 24 specimens, but not previously in eucrites. Specimens: 23 g including one polished thin section at UWB; remainder with Mr. R. Chaoui. | ||||||||||||||||||||||||||||
| Data from: MB109 Table 0 Line 0: |
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| Plots: | O isotopes: | ||||||||||||||||||||||||||||
| Institutions and collections |
UNM: Institute of Meteoritics
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126
USA, United States; Website (institutional address; updated 12 Feb 2015) UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012) WUSL: Washington Univ., One Brookings Drive, St. Louis, MO 63130, United States (institutional address; updated 17 Oct 2011) UWB: University of Washington, Burke Museum of Natural History and Culture, Box 353010 Seattle, WA 98195, United States (institutional address; updated 9 Oct 2023) |
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| Catalogs: |
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| References: | Published in Meteoritical Bulletin, no. 109, in preparation (2020)
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| Geography: |
Statistics: This is 1 of 9699 approved meteorites from (Northwest Africa) (plus 1854 unapproved names) | ||||||||||||||||||||||||||||
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| Revision history: |
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