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Name: NWA 998
Weight: 32mg
Type: Martian (nakhlite)
Total known weight: 456g meteorite-mars.com meteorite-mars.com THANK'S Size: 4x2x2 mm https://www.lpi.usra.edu/meteor/metbull.php?code=17921 Northwest Africa 998 Basic information Name: Northwest Africa 998 This is an OFFICIAL meteorite name. Abbreviation: NWA 998 Observed fall: No Year found: 2001 Country: (Northwest Africa) Mass:help 456 g Classification history: NHM Catalogue: 5th Edition (2000) Martian (shergottite) Meteoritical Bulletin: MB 87 (2003) Martian (nakhlite) MetBase: v. 7.1 (2006) Nakhlite Recommended: Martian (nakhlite) [explanation]
This is 1 of 19 approved meteorites classified as Martian (nakhlite). [show all] Search for other: Martian meteorites Writeuphelp Writeup from MB 87: Northwest Africa 998 Algeria or Morocco Purchased 2001 September Martian meteorite (nakhlite) A. and G. Hupé (xHupé) purchased, from dealers at the Tucson Gem and Mineral Show in 2002 February, the main mass from a 456 g stone that had been acquired at an unspecified site in western Algeria or eastern Morocco in 2001 September. Dimensions before cutting: 72 mm by 65 mm by 48 mm. Classification and mineralogy (A. Irving and S. Kuehner, UWS): a friable, dark green rock with minor orange-brown alteration products that probably are of pre-terrestrial origin. It is composed mainly of subhedral, olive-green, complexly zoned subcalcic augite (Fs22Wo39) with subordinate yellow olivine (Fa64), orthopyroxene (Fs49Wo4), interstitial plagioclase (Ab61Or4 containing 0.1 wt% SrO, and exhibiting normal birefringence), titanomagnetite, chlorapatite and pyrrhotite. The overall texture is that of a hypabyssal, adcumulate igneous rock, and the apparent crystallization sequence is olivine, orthopyroxene, titanomagnetite, augite, apatite, plagioclase. There is a weak preferred orientation of prismatic pyroxene crystals, many of which have very distinctive zoning, with cores of augite surrounded by irregular, inverted pigeonite rims (now consisting of orthopyroxene with fine augite lamellae). Trains of tiny melt inclusions are present along healed fractures within pyroxene; microprobe study confirms that most of these are K-Na-Al-bearing silicate glass, but some are intergrowths of glass and Fe-bearing carbonate, which may represent quenched immiscible silicate-carbonate liquids. Symplectitic intergrowths of titanomagnetite and low-Ca pyroxene are present at grain boundaries between large, discrete olivine and titanomagnetite grains, but are not present around chromian titanomagnetite inclusions within olivine. These observations suggest that a pre-terrestrial oxidation process produced the symplectites, and involved high temperature, deuteric fluid infiltration along grain boundaries; such fluids also may have produced the irregular pigeonitic rims on augite crystals. Secondary (probably pre-terrestrial) ankeritic carbonate, K-feldspar (some Fe-bearing), serpentine (?), calcite and a Ca sulfate are present on grain boundaries and within cracks in augite. Oxygen isotope composition (D. Rumble, CIW): replicate analyses of acid-washed augite by laser fluorination gave δ18O = +3.9 ± 0.2‰; δ17O = +2.4 ± 0.1‰; ∆17O = +0.30 ± 0.02‰. Specimens: type specimens, 20 g, UWS, 20 g, FMNH, and two polished thin sections, UWS; main mass, xHupé. Data from: MB87 Table 8 Line 32: Origin or pseudonym: Morocco/Algeria Place of purchase: Tucson, Az Date: Sep 2001 Mass (g): 456 Pieces: 1 Class: Martian Classifier: A. Irving, UWS Type spec mass (g): 40 Main mass: ROM Comments: see separate entry Plots: O isotopes: Institutions and collections FMNH: Department of Geology The Field Museum of Natural History 1400 South Lake Shore Drive Chicago, IL 60605-2496, USA, United States; Website (institutional address; updated 16 Nov 2011) ROM: Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada (institutional address; updated 18 Oct 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) CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address) xHupé: (old address—now see GHupé or AHupé) G. and A. Hupe, 2616 Lake Youngs Court SE, Renton, WA 98058., United States (private address) Catalogs: References: Published in Meteoritical Bulletin, no. 87, MAPS 38, A189-A248 (2003) Find references in NASA ADS: NASA ADS Find references in Google Scholar: Google Scholar Photos: Credit Photos Photos uploaded by members of the Encyclopedia of Meteorites. (Caution, these are of unknown reliability) abibou Added to database 7 Sep 2012 Aeroliths Collection Theodossiou Added to database 8 Jan 2012 AJS Cosmic Treasures Added to database 16 May 2010 Allmeteorite.com Added to database 29 Mar 2011 Argus Rocks Added to database 16 Aug 2009 bphd Added to database 26 Sep 2010 David Campbell Added to database 2 Sep 2009 Denis gourgues Added to database 24 Apr 2014 Gerald Armstrong Added to database 10 Feb 2010 Added to database 20 Apr 2010 J John Lutzon Added to database 13 Mar 2011 Jay Piatek Added to database 16 Jun 2009 Jim Strope Added to database 14 Feb 2012 MeteoriteCollector.org - FCOM - Russ Finney Added to database 31 Jan 2012 Michael S. Scherman Added to database 5 Jul 2009 Robert Zdancewicz Added to database 8 Nov 2011 Solar Anamnesis Added to database 28 Dec 2016 xeqtr Added to database 7 Feb 2013 Geography: Coordinates: Unknown.
Statistics: This is 1 of 5753 approved meteorites from (Northwest Africa) (plus 2068 unapproved names) Also see: See what others liked This lists the most popular meteorites among people who looked up this meteorite. Revision history: Revision history This lists important revisions made to data for this record. THANK S meteorite-mars.com THANK'S http://www.12dstring.me.uk/nwa.htm |