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| Northwest Africa 7258 | |||||||||||||||||||||||||||||||
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| Basic information | Name: Northwest Africa 7258 This is an OFFICIAL meteorite name. Abbreviation: NWA 7258 Observed fall: No Year found: 2011 Country: Morocco Mass:  310 g | ||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 330 approved meteorites (plus 2 unapproved names) classified as Martian (shergottite). [show all] Search for other: Martian meteorites | ||||||||||||||||||||||||||||||
| Comments: | Approved 25 May 2012 | ||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 100:
Northwest Africa 7258 (NWA 7258) Morocco Found: 2011 Classification: Martian meteorite (Shergottite) History: Purchased through Hmanis (Ali and Simon). Physical characteristics: Interior is pale green-tinged grey. A paper-thin patch of rusty discoloration is visible beneath the fusion crust. Shock classification S5, based on complete maskelynitization, and on mosaic extinction in pyroxenes. Petrography: Texture and mode are very Shergotty-like. Pyroxene (75 vol%) laths are up to 4 × 0.5 mm, mildly aligned; zoning shows Shergotty-like Wo-bimodality, starting near En59Wo11 and En46Wo34. Plagioclase/maskelynite (20 vol%) is Ab50Or2.2 to Ab52Or7 (59 analyses). Geochemistry: Bulk-rock INAA and fused-bead EPMA results from two 0.5-g chips include Ga/Al = 0.00051, Al2O3 = 5.2 wt%. REE are ~15 × CI chondrites, except REE near Tb ~20 × CI. Siderophile contents are at typical shergottite levels (e.g., 70 µg/g Ni). Classification: Bulk O-isotopic composition is martian (B-G. Choi and I. Ahn, CO2 laser-fluorination at KOPRI): δ18O = 4.716, δ17O = 2.804, and Δ17O = +0.33 (all per mil). Among NWA shergottites, it features a unique combination of mode, texture, and Al-poor, REE-rich bulk composition. Specimens: The UCLA material is derived from a single sawn corner of the meteorite. | ||||||||||||||||||||||||||||||
| Data from: MB100 Table 1 Line 1701: |
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| Plots: | O isotopes: | ||||||||||||||||||||||||||||||
| Institutions and collections |
UCLA: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, United States (institutional address; updated 17 Oct 2011) KOPRI: Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon, Korea, 406-840, South Korea; Website (institutional address; updated 20 Dec 2014) Thompson: Edwin Thompson, 5150 Dawn St., Lake Oswego, OR 97035, United States (private address) |
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| Catalogs: |
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| References: | Published in Meteoritical Bulletin, no. 100, MAPS 49, E1-E101 (2014)
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Geography:
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Statistics: This is 1 of 2163 approved meteorites from Morocco (plus 32 unapproved names) (plus 1 impact crater) | ||||||||||||||||||||||||||||||