[meteorite-list] a new martian nakhlite nwa5790

From: habibi abdelaziz <azizhabibi_at_meteoritecentral.com>
Date: Wed, 14 Oct 2009 16:07:28 -0700 (PDT)
Message-ID: <879516.16765.qm_at_web62003.mail.re1.yahoo.com>

hi all
i m very happy to announce a very rare nakhlite has been discovred and classified,
its nwa 5790 ;

here is the classification and photo

http://www.flickr.com/photos/azizhabibi/page3/

thanks
aziz habibi

Proposed Name NWA 5790 Geographic Coordinates1

City, County, province/state and Country Erfoud, Morocco
Find: 2009
Major classification (group) Martian (nakhlite)



History: Found in the desert by nomads and purchased by A. Habibi in Erfoud.
Physical characteristics: Two (136 + 9) g stones with millimetric phenocrysts in a groundmass with pinkish luster. Very friable.
Petrography: (A. Jambon, O. Boudouma, D. Badia, UPVI )
Millimetric euhedral dominant augite zoned over 10 micrormeter at the rim. Subsidiary euhedral olivine phenocrysts of similar size, zoned to their core. Intersitital mesostasis contains dendritic oxides pyroxene, feldspar, silica and glass. Mode from BSE images : Augite : 51.2, olivine 9.1, mesostasis 39.7, titanomagnetite <1%.

Mineral compositions (SEM and EMPA; as above) and geochemistry (ICP-MS; J-A Barrat UBO): zoned augite core (En35?Fs24 Wo40 and Fe/Mn = 32) sharp rim (En20Fs43 Wo36 and Fe/Mn = 42), olivine progressively zoned from the core (Fa65 with Fe/Mn = 47) to the rim (Fa80 with Fe/Mn = 40). Rare Ti-magnetite phenocrysts Uv32Mt56Sp7Ct4 with fine ilmenite exsolutions.
In the mesostasis dendritic crystals of Ti Magnetite : Uv52-74Mt38-19, acicular pyroxene (En7Fs47Wo46 and Fe/Mn = 55) and olivine Fa88. Plagioclase An16Ab79Or5;

Bulk major-element chemistry similar to other nakhlites; element ratios confirm martian origin (K/La =473, Ga/Al =3.7 104); significantly higher proportion of mesostasis than other nakhlites with the highest Th, U and rare earth elements (REE) concentrations ever reported for a nakhlite ( e.g. , Th = 0.85 ppm); REE pattern characterized by a strong light REE enrichment (La/Yb)n =5.8, and Eu/Eu* = 0.86.
 Oxygen isotopes (R. Greenwood and I. Franchi, OU ): ?17 O = ?.

Type specimens: A total sample mass of 20 g, are on deposit at UPVI ; main mass, Habibi .

habibi aziz
box 70 erfoud 52200 morroco
phone. 21235576145
fax.21235576170


      
Received on Wed 14 Oct 2009 07:07:28 PM PDT