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Northwest Africa 4284 | |||||||||||||||||||||||||
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Basic information | Name: Northwest Africa 4284 This is an OFFICIAL meteorite name. Abbreviation: NWA 4284 Observed fall: No Year found: 2005 Country: (Northwest Africa) Mass: ![]() | ||||||||||||||||||||||||
Classification history: |
This is 1 of 140 approved meteorites classified as Achondrite-ung. [show all] Search for other: Achondrites, Ungrouped achondrites | ||||||||||||||||||||||||
Comments: | Approved 23 Dec 2008 | ||||||||||||||||||||||||
Writeup![]() |
Writeup from MB 95:
Northwest Africa 4284 Algeria Find: 2005 Achondrite (ungrouped) History: A 137 g partial stone with partial crust was purchased in Erfoud, Morocco in 2005. Petrography (T. Bunch and J. Wittke, NAU): Igneous textures include hypidimorphic-granular, ophitic, and poikilitic (orthopyroxene oikocrysts enclose olivine). NWA 4284 is composed of mm to submillimeter-sized grains of (in order of abundance) orthopyroxene, olivine, plagioclase, Ca pyroxene, FeS, and chromite. Taenite metal occurs in rare, isolated clusters of coarser-grained orthopyroxene-olivineplagioclase- taenite. Geochemistry: Orthopyroxene, Fs24.5Wo3.5, FeO/MnO = 28–30; olivine, Fa24.6, FeO/MnO = 46–54; plagioclase. An11Or5.3; Ca pyroxene, Fs8.2Wo44.2; chromite, Cr# = 0.88; and taenite, Ni = 21.5 (no kamacite was found). Oxygen isotopes (D. Rumble, CIW): a cleaned and metal-free sample was analyzed by laser fluorination. Replicate analyses are, respectively, δ17O = 3.253, 3.227‰; δ18O = 4.195. 4.247‰; Δ17O = 1.046, 0.993‰. Classification: Achondrite (ungrouped). Mineral compositions and oxygen isotopes indicate that this stone has an L chondrite heritage, but the lack of chondrules and obvious igneous textures, indicate a later melt origin. Specimens: type example, 21 g and one thin section, NAU; main mass holder is Edwin Thompson. | ||||||||||||||||||||||||
Data from: MB95 Table 2 Line 45: |
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Plots: | O isotopes: | ||||||||||||||||||||||||
Institutions and collections |
NAU: Geology, Bldg 12
Knoles Dr
Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012) CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address) 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. 95, MAPS 44, 429-462 (2009)
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Geography: |
Statistics: This is 1 of 9429 approved meteorites from (Northwest Africa) (plus 1876 unapproved names) |