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| Northwest Africa 12869 | |||||||||||||||||||||||||||||||
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| Basic information | Name: Northwest Africa 12869 This is an OFFICIAL meteorite name. Abbreviation: NWA 12869 Observed fall: No Year found: 2019 Country: Mali Mass:  4.3 kg | ||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 15 approved meteorites classified as Achondrite-prim. [show all] Search for other: Primitive achondrites | ||||||||||||||||||||||||||||||
| Comments: | Approved 21 Sep 2019 | ||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 108:
Northwest Africa 12869 (NWA 12869) Mali Purchased: 2019 Classification: Primitive achondrite History: Single stone purchased by Abdelhadi Aithiba in Taoudenni, Mali, 2019. Physical characteristics: Dark brown, weathered, irregular shaped exterior. Broken surfaces show dark brown, green, and honey-colored grains. Petrography: (C. Agee, UNM) This meteorite contains approximately 70% olivine, 20% low-Ca pyroxene, 5% plagioclase, and 10% kamacite+troilite. The texture is poikiolitic to equigranular with typical grain sizes 100-500 μm. Many triple junctions are present. Fine crosscutting Fe-oxide veinlets were seen throughout. No chondrules observed. Geochemistry: (C. Agee, UNM) Olivine Fa34.7±0.2, Fe/Mn=86±5, n=10; low-Ca pyroxene Fs26.2±1.3Wo3.6±0.4, Fe/Mn=58±8, n=6; plagioclase An47.4±0.5Ab51.5±0.5Or1.2±0.1, n=4. Oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave δ18O= 3.668, 3.584, 3.181; δ17O= 0.225, 0.170, -0.072; Δ17O= -1.712, -1.722, -1.752 (linearized, per mil, TFL slope=0.528). Classification: Primitive achondrite. This a plagioclase-bearing harzburgite with oxygen isotopes similar to CR/CH chondrites, however the high Fa-content and Fe/Mn of olivine is inconsistent with a direct genetic link to CR/CH. Possibly paired with or related to NWA 3250 and NWA 6901, and broadly similar in geochemistry to other primitive achondrites that have olivine compositions ~Fa30-35 and oxygen isotopes in the vicinity of the CR/CH field such as NWA 3100 and Tafassasset. Specimens: 22 g including a probe mount on deposit at UNM, Abdelhadi Aithiba holds the main mass. | ||||||||||||||||||||||||||||||
| Data from: MB108 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) |
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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:
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Statistics: This is 1 of 93 approved meteorites from Mali (plus 2 unapproved names) | ||||||||||||||||||||||||||||||