| MetSoc Home Publications Contacts |
|
||
|
||
| Northwest Africa 12991 | |||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Basic information | Name: Northwest Africa 12991 This is an OFFICIAL meteorite name. Abbreviation: NWA 12991 Observed fall: No Year found: 2017 Country: Morocco Mass:  3.48 kg | ||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 7227 approved meteorites (plus 4 unapproved names) classified as L5. [show all] Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7) | ||||||||||||||||||||||||||||||
| Comments: | Approved 21 Nov 2019 | ||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 108:
Northwest Africa 12991 (NWA 12991) Morocco Purchased: 2017 Mar 08 Classification: Ordinary chondrite (L5) Physical characteristics: Hand specimen shows weathered fusion crust. Cut surface indicates pervasive weathering with oxidised metal and rust staining throughout. Petrography: Chondrules are dominantly porphyritic with typical size of 800-1000 μm, with one notably large chondrule observed at > 4 mm. Few exhibit discernible edges but most are poorly delineated and chondrule fragments blend in with the recrystallized matrix. Metal grains average at 200 µm in length with modal abundance of ~4 vol%. Both metals and sulphide grains are heavily weathered, and alteration veins are pervasive. Plagioclase grains are dominantly <50 µm in length. Geochemistry: Mineral composition and geochemistry: All analyses by EPMA. Olivine: Fa25.4±0.6 (N=49). Pyroxene: Fs21.6±0.6En77.0±0.7Wo1.4±0.3 (N=43). Plagioclase: Ab84.1±1.6An10.2±0.6Or5.7±1.8 (N=27). Metal and sulphide analyses had low totals due to weathering. | ||||||||||||||||||||||||||||||
| Data from: MB108 Table 0 Line 0: |
|
||||||||||||||||||||||||||||||
| Institutions and collections |
NHM: Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom; Website (institutional address; updated 9 Dec 2011) ICL: Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom (institutional address) |
||||||||||||||||||||||||||||||
| Catalogs: |
| ||||||||||||||||||||||||||||||
| References: | Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
| ||||||||||||||||||||||||||||||
Geography:
|
Statistics: This is 1 of 1680 approved meteorites from Morocco (plus 25 unapproved names) (plus 1 impact crater) | ||||||||||||||||||||||||||||||