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| Northwest Africa 12817 | |||||||||||||||||||||||||||||||||
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| Basic information | Name: Northwest Africa 12817 This is an OFFICIAL meteorite name. Abbreviation: NWA 12817 Observed fall: No Year found: 2018 Country: (Northwest Africa) Mass:  127 g | ||||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 119 approved meteorites classified as Eucrite-unbr. [show all] Search for other: Achondrites, Eucrites, and HED achondrites | ||||||||||||||||||||||||||||||||
| Comments: | Approved 18 Aug 2019 | ||||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 108:
Northwest Africa 12817 (NWA 12817) (Northwest Africa) Purchased: 2018 Classification: HED achondrite (Eucrite, unbrecciated) History: Marc Jost acquired the 12 7g sample from Giorgio Tomelleri at the St Marie aux Mines show in 2018. Physical characteristics: The exterior is covered by a ~1mm thick, dark brown, bumpy fusion crust. Pyroxenes protrude through the surface of the crust as blocky, brown crystals. The cut face shows the interior is composed of light orange and white interlocking crystals with an igneous texture. Petrography: Description and classification (A. Love, App): Sample is a coarse-grained, unbrecciated, ophitic-textured basalt with 990 μm euhedral to subhedral plagioclase laths enclosed by 4 mm exsolved pigeonites. Some margins of pyroxenes show they have been recrystallized into smaller sub grains with 120º grain boundaries. Additional minerals are: ilmenite, chromite, zircon, phosphate and a silica polymorph. Geochemistry: (A. Love, App) Low Ca pyroxene Fs61.9±0.9Wo5.3±1.0 (Fs60.2-63.1Wo4.1-7.2), Fe/Mn=30.4±0.4, Mg#=34.8, N=22; high Ca pyroxene Fs32.7±0.5 Wo39.9±0.6 (Fs31.7-33.7Wo38.9-41.2), Fe/Mn=32.3±0.9, N=15; plagioclase An89.1±2.1Or0.4±0.1 (An86.3-91.4Or0.2-0.7), N=8. Classification: Achondrite (gabbroic eucrite, unbrecciated). Based on ophitic texture, equilibrated compositions, Fe/Mn and Mg# of pigeonites, this sample is a coarse-grained, unbrecciated, equilibrated gabbroic eucrite. This sample corresponds to a type 6 eucrite of Takeda and Graham (1991) based upon inversion of original pigeonite and equilibrated compositions of pyroxenes. Specimens: Marc Jost (SJS) holds the main mass. 2 slices weighing 20.5 g, a mount and polished thin section are on deposit at App. | ||||||||||||||||||||||||||||||||
| Bibliography: |
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| 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 8559 approved meteorites from (Northwest Africa) (plus 1896 unapproved names) | ||||||||||||||||||||||||||||||||