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Northwest Africa 2907 | |||||||||||||||||||||||
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Basic information | Name: Northwest Africa 2907 This is an OFFICIAL meteorite name. Abbreviation: NWA 2907 Observed fall: No Year found: 2005 Country: (Northwest Africa) Mass: 586 g | ||||||||||||||||||||||
Classification history: |
This is 1 of 151 approved meteorites classified as Achondrite-ung. [show all] Search for other: Achondrites, Ungrouped achondrites | ||||||||||||||||||||||
Comments: | Approved 28 Mar 2007 | ||||||||||||||||||||||
Writeup |
Writeup from MB 91:
Northwest Africa 2907 Northwest Africa Find: 2005 Achondrite (ungrouped) History: A large number of pieces were collected within a small strewn field of ~15 m in diameter in Algeria and sold in Erfoud, Morocco. Physical characteristics: Most of the fragments composing the 586 g mass are without fusion crust, dark brown in color, and show extensive surface weathering. Petrography: (T. Bunch and J. Wittke, NAU) Partially recrystallized polymict breccia that contains at least two distinct lithologies: a) medium-grained clasts (<2 mm) of untwinned orthopyroxene without discernible exsolution lamellae and a roughly equal amount of complex, polysynthetically twinned plagioclase partially converted to maskelynite; and b) medium-grained, partially recrystallized pigeonite with minor development of exsolution lamellae and twinning with inclusions of simple, albite-twinned plagioclase together with a fine-grained assemblages (<0.1 mm) of tridymite, metal, and plagioclase at recrystallization boundaries. Both lithologies are set in a fine-grained, partially recrystallized matrix of pyroxenes and plagioclase compositionally similar to lithologies (a) and (b). Minor minerals include Al-rich chromite, a sulfide phase, tridymite, phosphate, and metal. Mineral compositions and geochemistry: Lithology (a): orthopyroxene (cores = Fs22.0–25.3Wo2.5; FeO/MnO = 24–27 with grain margins of Fs33.8Wo7.2 that in turn have exsolved Ca-rich pyroxene), plagioclase (An99.5Or0.5). Lithology (b): pigeonite (Fs38.1Wo11.1), plagioclase (An94.8Or5.6). Classification: Achondrite (ungrouped); S3, moderate weathering. Overall characteristics of this meteorite are similar to clast material in some mesosiderites and may represent a large, separated mesosiderite clast. Type specimen: A total of 23 g is on deposit at NAU. Reed holds the main mass. | ||||||||||||||||||||||
Data from: MB91 Table 2 Line 118: |
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Institutions and collections |
NAU: Geology, Bldg 12
Knoles Dr
Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012) Reed: Blaine Reed, P.O. Box 1141, Delta, CO 81416, United States; Website (private address) |
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Catalogs: |
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References: | Published in Meteoritical Bulletin, no. 91, MAPS 42, 413-466 (2007)
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Geography: |
Statistics: This is 1 of 9699 approved meteorites from (Northwest Africa) (plus 1854 unapproved names) | ||||||||||||||||||||||
Also see: |
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Revision history: |
This lists important revisions made to data for this record.
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