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| Northwest Africa 12861 | |||||||||||||||||||||||||||||||||||
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| Basic information | Name: Northwest Africa 12861 This is an OFFICIAL meteorite name. Abbreviation: NWA 12861 Observed fall: No Year found: 2014 Country: (Northwest Africa) Mass:  29 g | ||||||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 622 approved meteorites classified as CM2. [show all] Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 2), CM chondrites, and CM-CO clan chondrites | ||||||||||||||||||||||||||||||||||
| Comments: | Approved 21 Sep 2019 | ||||||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 108:
Northwest Africa 12861 (NWA 12861) (Northwest Africa) Purchased: 2014 Classification: Carbonaceous chondrite (CM2) History: Marc Jost purchased the 28.97 g sample from sellers in Sidi Ifni, Morocco, March, 2014. Physical characteristics: The sample has an irregular rounded shape and is coated in a flow-lined, black contraction-cracked fusion crust. The cut face shows the interior has a chondritic texture composed of a mostly small chondrules and CAIs set within a black fine-grained matrix. Petrography: Description and classification (A. Love, App) Sample has a brecciated chondritic texture composed of chondrules, fragments, and CAIs distributed throughout a black fine-grained matrix (~60 vol%). Chondrules have an average apparent diameter of 226 µm (N=33) and are primarily porphyritic chondrules with altered mesostasis. All components are surrounded by fine-grained, dust mantles. Additional minerals are: pentlandite, calcite, chromite, tochilinite, pyrrhotite, kamacite. Geochemistry: Olivine (Type I Chondrules Fa0.7±0.2 (Fa0.6-1.0), N=5, Type II chondrules Fa29.0±9.9 (Fa13.7-44.6), Cr2O3 in ferroan olivines=0.4±0.1, N=11), low Ca pyroxene Fs6.1±10.4Wo1.1±0.9 (Fs0.7-39.0Wo0.3-4.0, N=14). Classification: Carbonaceous chondrite (CM2) Based on matrix abundance, chondrule size, mineralogy and magnetic susceptibility, this is a CM carbonaceous chondrite. Based on the abundance of unaltered silicates this is a CM2. Specimens: Marc Jost (SJS) holds the main mass. An end cut weighing 7.48 g and a polished mount are on deposit at App. | ||||||||||||||||||||||||||||||||||
| Data from: MB108 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) SJS: Space Jewels Switzerland, 2555 Brügg, Switzerland (private address; updated 3 Jan 2010) |
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| Catalogs: |
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| References: | Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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| Geography: |
Statistics: This is 1 of 9092 approved meteorites from (Northwest Africa) (plus 1875 unapproved names) | ||||||||||||||||||||||||||||||||||