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| Northwest Africa 16533 | |||||||||||||||||||||||||||||||
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| Basic information | Name: Northwest Africa 16533 This is an OFFICIAL meteorite name. Abbreviation: NWA 16533 Observed fall: No Year found: 2022 Country: (Northwest Africa) Mass:  300 g | ||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 2 approved meteorites classified as Howardite-an. [show all] Search for other: Achondrites, HED achondrites, and Howardites | ||||||||||||||||||||||||||||||
| Comments: | Approved 30 Mar 2024 | ||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 113:
Northwest Africa 16533 (NWA 16533) (Northwest Africa) Purchased: April 2022 Classification: HED achondrite (Howardite, anomalous) History: Purchased in April 2022 by Tim Stout from a meteorite dealer in Tindouf Algeria. Physical characteristics: Single stone with a moderately weathered dark brown fusion crust. Petrography: (D. Sheikh, Cascadia) Specimen represents a polymict breccia composed of a mix of lithic and monomineralic clasts/clast fragments (most sub-mm, largest ~4 mm) set within a fine-grained fragmental matrix. Diogenitic and eucritic (primarily basaltic clasts with few cumulate clasts) components comprise ~80 vol. % and ~20 vol. % of the clast inventory, respectively. Pyroxenes in the eucritic portion typically display thin, sub-μm-sized bands of exsolution lamellae. Anomalous monomineralic Mg-rich olivine and low-Ca pyroxene clasts are present in the diogenitic portion of this sample. Accessory phases identified in the sample include chromite, silica polymorph, and troilite. Geochemistry: Diogenitic Component [Regular Olivine (Fa28.7±2.6, range Fa25.7-30.6, Fe/Mn=45±5, n=3), Mg-rich Olivine (Fa12.2±0.9, range Fa10.4-12.9, Fe/Mn=38±4, n=11), Regular Low-Ca Pyroxene (Fs25.3±3.3Wo2.0±0.6, range Fs21.5-36.2Wo1.1-3.5, Fe/Mn=28±2, n=22), Mg-rich Low-Ca Pyroxene (Fs15.6±2.1Wo1.3±0.7, range Fs12.6-17.5Wo0.6-2.1, Fe/Mn=31±3, n=4)]; Eucritic Component [Low-Ca Pyroxene (Fs59.0±7.1Wo2.9±1.2, range Fs41.3-63.9Wo1.4-4.6, Fe/Mn=30±2, n=16), Pigeonite (Fs56.6±6.5Wo8.4±3.2, range Fs43.8-62.9Wo5.4-12.8, Fe/Mn=30±1, n=7), High-Ca Pyroxene (Fs32.7±6.9Wo37.1±5.7, range Fs15.8-44.9Wo25.6-44.7, Fe/Mn=31±3, n=15), Calcic Plagioclase (An82.9±4.9, range An75.2-93.3, n=17)]. Classification: Howardite (anomalous) due to the presence of unusual, Mg-rich monomineralic olivine and pyroxene mineral fragments that are compositionally similar to Mg-rich olvine and Low-Ca pyroxene mineral clasts from howardites reported in Lunning et al. 2015, Mg-rich harzburgites reported in Hahn et al. (2018) and Mg-rich olivines and low-Ca pyroxenes reported in anomalous diogenite Djebel Chaab 004. Specimens: 23.7 g at Cascadia, main mass with Tim Stout. | ||||||||||||||||||||||||||||||
| Bibliography: |
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| Data from: MB113 Table 0 Line 0: |
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| Institutions and collections |
Cascadia: Cascadia Meteorite Laboratory, Portland State University, Department of Geology, Room 17 Cramer Hall, 1721 SW Broadway, Portland, OR 97201, United States; Website (institutional address; updated 28 Oct 2011) |
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| Catalogs: |
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| References: | Published in Meteoritical Bulletin, no. 113, in preparation (2024)
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| Geography: |
Statistics: This is 1 of 9933 approved meteorites from (Northwest Africa) (plus 1837 unapproved names) | ||||||||||||||||||||||||||||||