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Northwest Africa 6999 | |||||||||||||||||||||||||||||||
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Basic information | Name: Northwest Africa 6999 This is an OFFICIAL meteorite name. Abbreviation: NWA 6999 Observed fall: No Year found: 2000 Country: (Northwest Africa) Mass: 7.47 kg | ||||||||||||||||||||||||||||||
Classification history: |
This is 1 of 22 approved meteorites classified as L/LL4. [show all] Search for other: L chondrites, L/LL chondrites, L/LL chondrites (type 4-7), LL chondrites, Ordinary chondrites, and Ordinary chondrites (type 4-7) | ||||||||||||||||||||||||||||||
Comments: | Approved 7 Jul 2012 | ||||||||||||||||||||||||||||||
Writeup |
Writeup from MB 101:
Northwest Africa 6999 (NWA 6999) (Northwest Africa) Purchased: Aug 2000 Classification: Ordinary chondrite (L/LL4) History: A 7.465 kg meteorite was purchased by David Gregory in August 2000 as part of a collection of NWA 869 strewn field material. Physical characteristics: The meteorite is composed of heterogeneous ordinary chondrite material with no obvious brecciation. The fusion crust is generally rust-brown and variable in its degree of terrestrial weathering and thickness. Several fractures are visible through the fusion crust and are observed as shock veins. The interior is beige gray, with iron staining proximal to the fusion crust and shock veins/fractures. Petrography: (K. van Drongelen, ROM) Meteorite composed of chondrules (70%), troilite (5%), Ni-Fe metal and oxides (5%) and matrix material. Chondrules show a varied degree of definition from clearly to poorly defined with no obvious preferred spatial distribution and consist of barred olivine, porphyrytic olivine, pyroxene, and olivine-pyroxene; radial pyroxene; and granular chondrules. Chondrules range from 0.5 to 6.5 mm in diameter, with an average of 1.5-2.0 mm, and are generally sub-circular in shape. Troilite and Ni-Fe metal consist of individual grains, grains within chondrules, and shock veins. The matrix (grain size <50-500 μm) ranges from easy to difficult to distinguish from chondrules and chondrule fragments. The meteorite contains shock veins and melt pockets, which are also found as a concentration in the center of the cut face (a macroscopically visible darkened area). Olivine exhibit irregular fractures, undulose extinction, and fine planar fractures. Geochemistry: (Katrina van Drongelen, ROM) Olivine Fa=25.9±2.2 (n=66); low-Ca pyroxene (n=31) Fs23En75Wo2; high-Ca pyroxene (n=15) Fs16En52Wo32. Classification: (Katrina van Drongelen, ROM) Ordinary Chondrite (L/LL4), S3, W2. Specimens: Five thin sections and 7.387 kg are on deposit at the ROM. | ||||||||||||||||||||||||||||||
Data from: MB101 Table 0 Line 0: |
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Institutions and collections |
ROM: Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada (institutional address; updated 18 Oct 2011) |
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Catalogs: |
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References: | Published in Meteoritical Bulletin, no. 101, MAPS 50, 1661, September 2015
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Geography: |
Statistics: This is 1 of 9627 approved meteorites from (Northwest Africa) (plus 1865 unapproved names) | ||||||||||||||||||||||||||||||
Also see: |
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Revision history: |
This lists important revisions made to data for this record.
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