Date: 2013 Latitude: 24.767°N Longitude: 13.0184°W Mass (g): 682 Pieces: 4 Class: Eucrite-mmict Classifier: C. Agee, UNM Type spec mass (g): 23.2 Type spec location: UNM Main mass: Ahmed Akhebbach and Ayoub Oumoussa Finder: Mohmed and Mahdi Zergou Comments: Field name Zbayra; submitted by C. Carl Agee Northwest Africa 8187 (NWA 8187) 24.767°N, 13.0184°W Western Sahara Found: 2013 Classification: HED achondrite (Eucrite, monomict) History: (H. Chennaoui Aoudjehane) Found in a small depression, late June 2013, by Mohmed and Mahdi Zergou while tending of herd of camels in the Zbayra area, near Guelta Zemmour, about 250 km southwest of Smara. A meteorite hunter Ahmed Akhebbach recognized the stone as a meteorite -- possibly a eucrite, collected the geographic coordinates, purchased it, and Ayoub Oumoussa submitted a deposit piece for classification. Physical characteristics: Main mass 640 g, totally covered by black fusion crust, except one broken surface, plus smaller pieces found with it: 23 g, 15 g, 3 g. Interior reveals fresh, light gray, very fine-grained groundmass. Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows a protogranular texture with approximately 50% pyroxene and 50% plagioclase, grain size 10-100 μm, many pyroxenes with exsolution lamellae. Millimeter-sized monomict clasts. Accessory low-Ni iron metal, silica, ilmenite, and troilite. Geochemistry: (C. Agee and N. Muttik, UNM) EMPA. Low Ca-pyroxene Fs59.4±2.6Wo5.0±2.7, Fe/Mn=32±1, n=8; high-Ca pyroxene Fs30.0±2.6Wo39.7±3.1, Fe/Mn=34±2; n=6; plagioclase Or0.6±0.1Ab11.3±0.7An88.1±0.7, n=4. Classification: Achondrite, equilibrated, monomict basaltic eucrite. Specimens: 23.2 g including a probe mount on deposit at UNM, Ahmed Akhebbach and Ayoub Oumoussa jointly hold the main mass
Posted on: Sat, 22 Mar 2014 11:48:11 +0000
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