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| Northwest Africa 15622 | |||||||||||||||||||||||||||||||
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| Basic information | Name: Northwest Africa 15622 This is an OFFICIAL meteorite name. Abbreviation: NWA 15622 Observed fall: No Year found: 2022 Country: (Northwest Africa) Mass:  700 g | ||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 79 approved meteorites (plus 1 unapproved name) classified as Winonaite. [show all] Search for other: Primitive achondrites, Winonaites | ||||||||||||||||||||||||||||||
| Comments: | Approved 29 Jan 2023 | ||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 112:
Northwest Africa 15622 (NWA 15622) (Northwest Africa) Purchased: 2022 Classification: Primitive achondrite (Winonaite) History: A single 671 g sample was purchased in Tindouf, Algeria, from Ali Mftah by Mark Lyon and Shun-Chung Yang in Nov 2022. Physical characteristics: A portion of the tabular sample is covered by a weathered black fusion crust. The opposing side shows shallow regmaglypts. The cut face shows the sample has a fine-grained crystalline texture composed of silicates crosscut by anastomosing veins of metal and sulfide. Petrography: Description and classification (A. Love, App) Sample shows: granoblastic texture composed of (vol%): enstatite (49), forsterite (21), fine-grained diopside (1) and kamacite (low Si-0,13 wt%), taenite and troilite. Chondrules are absent. Thin section of silicate portion shows variation in grainsize (avgs. of different regions 158µm; 268µm; 386µm) and variation of sulfide and Fe metal abundance within these grain size ranges. Additional minerals are: albitic plagioclase, schreibersite, alabandite, daubréelite (present as lamellae within troilite) and graphite. Geochemistry: (A. Love, App) Olivine Fa0.4±0.2 (Fa0.3-1.3, Fe/Mn=4.3±1.7, n=13); enstatite (Fs0.3±0.1Wo1.6±0.5, Fe/Mn=3.8±0.2 n=12); diopside (Fs0.4±0.2Wo46.0±0.9, n=8); albitic plagioclase (Ab77.1±4.1Or1.9±0.6, n=7). Classification: Primitive achondrite (winonaite U-S5 low weathering). Nearly iron-free mineral compositions, presence of: rare sulfides; graphite and phosphide mineralogy, granoblastic texture, absence of chondrules, presence of highly ordered enstatite as indicated by cathodoluminescence (Zhang et al, 1996) are similar to enstatite chondrites. The modal abundance of both forsterite and plagioclase and aforementioned mineralogy and texture suggests the sample is a winonaite. Presence of a metal and sulfide veins and a single melt dike suggest sample has experienced shock levels up to U-S5. Specimens: Mark Lyon holds the 340 g main mass. Shun-Chung Yang holds a 331 g piece. A polished thin section and slice weighing 23.01 g are on deposit at App. | ||||||||||||||||||||||||||||||
| Data from: MB112 Table 0 Line 0: |
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| Institutions and collections |
App: Department of Geology, 572 Rivers St., Appalachian State University, Boone, NC 28608, United States (institutional address; updated 7 Mar 2013) |
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| Catalogs: |
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| References: | Published in Meteoritical Bulletin, no. 112, in preparation (2023)
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| Photos: |
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| Geography: |
Statistics: This is 1 of 9013 approved meteorites from (Northwest Africa) (plus 1869 unapproved names) | ||||||||||||||||||||||||||||||