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| Northwest Africa 8231 | |||||||||||||||||||||||||||||||
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| Basic information | Name: Northwest Africa 8231 This is an OFFICIAL meteorite name. Abbreviation: NWA 8231 Observed fall: No Year found: 2005 Country: (Northwest Africa) Mass:  356 g | ||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 114 approved meteorites classified as H4-6. [show all] Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7) | ||||||||||||||||||||||||||||||
| Comments: | Approved 1 Feb 2014 | ||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 103:
Northwest Africa 8231 (NWA 8231) (Northwest Africa) Purchased: Oct. 2005 Classification: Ordinary chondrite (H4-6) History: A single stone of 356 g, supposedly found south of Zagora, Morocco, was obtained by Edwin Thompson from a trader in October 2005. A 28 g slice and crumbs from this stone were donated by Thompson to Cascadia on Dec. 13, 2005, and the remaining available mass (325.1 g in two pieces) was purchased from Patrick Thompson on Aug. 15, 2013. Physical characteristics: The specimen has a largely fusion crusted surface that appears brown-gray with reddish weathering patches. Cut surfaces show an interior with irregularly-shaped light-colored inclusions and brown-stained host with a breccia texture and some thin shock veins. Petrography: (K. Armstrong and A. Ruzicka, Cascadia) The host has a brecciated, chondritic texture and appears "blackened" in transmitted light caused by the presence of fine-grained troilite and metal and weathering product. Chondrule size is 0.6±0.2 mm (N = 26), with chondrules more distinct in some regions than others. Some feldspar grains are >50 μm across but most feldspar is finer-grained. Larger metal and troilite grains comprise 6.5±0.6 and 5.3±0.3 area% of the host, respectively, determined by pixel counting in reflected light images. Geochemistry: Mineral compositions and geochemistry: Representative olivine is Fa19.4±0.4, and Fe/Mn = 38.6±7.5 (N = 37). Low-Ca pyroxene is Fs17.2±0.3Wo1.2±0.1 (N = 25). A small amount of slightly magnesian olivine and pyroxene grains were noted in BSE images. Classification: Mineral chemistry and textures point to a dominance of H5 material, but the meteorite appears to be an H4-6 breccia based on the presence of some regions with poorly-defined chondrules and coarse feldspar, and the rare occurrence of slightly magnesian olivine and pyroxene grains. The meteorite was extensively shock-blackened. Specimens: Type specimens at Cascadia include the main mass (284.2 g), five separate cut pieces totaling 59.2 g, and a polished thin section and potted butt. | ||||||||||||||||||||||||||||||
| Data from: MB103 Table 0 Line 0: |
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| Institutions and collections |
Cascadia: Cascadia Meteorite Laboratory, Portland State University, Department of Geology, Room 17 Cramer Hall, 1721 SW Broadway, Portland, OR 97201, United States; Website (institutional address; updated 28 Oct 2011) Thompson: Edwin Thompson, 5150 Dawn St., Lake Oswego, OR 97035, United States (private address) |
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| Catalogs: |
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| References: | Published in Meteoritical Bulletin, no. 103, MAPS 52, 1014, May 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12888/full
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| Geography: |
Statistics: This is 1 of 9933 approved meteorites from (Northwest Africa) (plus 1837 unapproved names) | ||||||||||||||||||||||||||||||