|Northwest Africa 7325|
|Basic information||Name: Northwest Africa 7325|
This is an OFFICIAL meteorite name.
Abbreviation: NWA 7325
Observed fall: No
Year found: 2012
Country: (Northwest Africa)
Mass: 345 g
This is 1 of 58 approved meteorites classified as Achondrite-ung. [show all]
Search for other: Achondrites, Ungrouped achondrites
|Comments:||Approved 18 Dec 2012|
Writeup from MB 101:
Northwest Africa 7325 (NWA 7325)
Purchased: 2012 Apr
Classification: Ungrouped achondrite
History: Purchased by Stefan Ralew in April 2012 from a dealer in Erfoud, Morocco. The material was found reportedly in southern Morocco in early 2012.
Physical characteristics: A group of 35 very fresh, dark greenish stones (total 345 g), several of which have partial remnant chartreuse-colored fusion crust. This material is notable for the characteristic "frosty" luster of the plagioclase and bright green color of the clinopyroxene.
Petrography: (A. Irving and S. Kuehner, UWS): The studied specimen has an overall plutonic igneous (possibly cumulate) texture. It is a medium-grained aggregate of Al-Cr-bearing diopside, calcic plagioclase and lobate (possibly resorbed) grains of forsterite, with accessory Cr-bearing iron sulfide (probably troilite), very sparse ferrochromite, kamacite and taenite, and rare eskolaite (associated with Cr-Fe sulfide). In thin section the untwinned plagioclase is birefringent, but the levels of birefringence are less than normal and variable on a fine scale (suggesting the existence of compositional and/or structural microdomains); there also are sparse vesicles (suggesting at least partial melting). The pyroxene exhibits at least two sets of polysynthetic twin lamellae, which resemble those produced by moderately high shock.
Geochemistry: Clinopyroxene (Fs1.1-2.6 Wo45.1-44.5, FeO/MnO = 12-21, Al2O3 = 2.6-2.8 wt.%, Cr2O3 = 1.0 wt.%), plagioclase (An88.1-89.2Or0.0), olivine (Fa2.7-2.8, FeO/MnO = 30-36, CaO = 0.27-0.32 wt.%, Cr2O3 = 0.32-0.35 wt.%). Bulk composition (G. Chen, UAb): analyses of representative bulk wire-saw cutting dust by ICP-MS gave: (in ppm) La 0.15, Ce 0.34, Nd 0.16, Sm 0.05, Eu 0.58, Gd 0.05, Hf 0.44, Th 0.27. Oxygen isotopes (K. Zeigler, UNM): laser fluorination analyses of acid-washed subsamples gave, respectively δ17O = 3.214, 3.670, 3.249; δ18O = 7.566, 8.204, 7.957; Δ17O = -0.781, -0.662, -0.952 per mil [for TFL slope of 0.528].
Classification: Achondrite (ungrouped). The combination of highly magnesian mafic silicates and highly calcic plagioclase with chromium-bearing sulfides is unique among achondrites, and the specimen is highly depleted in most trace elements.
Specimens: A total of 21 g of type material and one polished thin section are on deposit at UWB. The remaining material is held by Ralew.
UNM: Institute of Meteoritics
University of New Mexico
Albuquerque NM 87131-1126
USA, United States; Website (institutional address; updated 26 Dec 2011)
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
UAb: 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB, T6G 2E3, Canada, Canada; Website (institutional address; updated 17 Oct 2011)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
Ralew: Stefan Ralew, Kunibertstraße 29, 12524 Berlin, Germany; Website (private address)
|References:||Published in Meteoritical Bulletin, no. 101, MAPS 47, in preparation (2013)|
This is 1 of 3847 approved meteorites from (Northwest Africa) (plus 2493 unapproved names)
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