Northwest Africa 4480 Martian Meteorite

Complete mass of NWA 4480.
Complete mass of NWA 4480.

Official Meteoritical Bulletin entry for Northwest Africa 4480:

Northwest Africa 4480
     Find: Summer 2006
     Achondrite (Martian, basaltic shergottite)

History: The sample was recovered in Algeria in the summer of 2006. G. Hupé purchased it in Tagounite, Morocco in September 2006.
Physical characteristics: The meteorite is a single, very fresh 13 g ellipsoidal stone, mostly coated by dark brown fusion crust. Maskelynite, yellow-green olivine and tan-coloured pyroxene are visible on cut face.
Petrography: (A. Irving and S. Kuehner, UWS) The stone is mostly a relatively fine-grained (mean grainsize 0.15 mm) basaltic rock, but with several coarser grained, glomerocrystic regions. The dominant matrix consists of plagioclase laths (maskelynite), olivine and complexly-zoned clinopyroxene with accessory Ti-chromite, ilmenite, Mg-Fe-bearing merrillite and rare Si-rich glass or silica polymorph. Glomerocryst regions are composed of coarser (0.5-0.8 mm) plagioclase (maskelynite) and olivine with interstitial pigeonite and ilmenite.
Mineral compositions and geochemistry: Matrix - clinopyroxene is patchily zoned from augite cores (Fs24.9-31.2Wo35.3-31.1, FeO/MnO = 30-32) to pigeonite rims (Fs55.4-56.4Wo17.5-15.4, FeO/MnO = 36); olivine (Fa67.9-79.2, FeO/MnO = 49-52); plagioclase (An58.4-61.0 Or1.6). Plagioclase in glomerocryst regions is consistently more calcic (An66.3-68.5Or0.3). Bulk Composition (R. Korotev, WUSL): INAA of two ~37 mg whole fragments of matrix gave Na 1.40 wt%, Fe 15.8 wt%, and (in ppm) Sc 39.7, Cr 1027, Ni <60, La 1.85, Sm 2.69, Eu 0.86, Tb 1.05, Yb 4.16, Hf 3.16, Th 0.24; the REE pattern shows moderate light REE depletion, elevated heavy REE abundances and a negative Eu anomaly.
Classification: Achondrite (Martian, basaltic shergottite).
Type specimens: A total of 2.6 g of sample is on deposit at UWS. PSF holds the main mass (6.63 g).

Scientific abstracts and news regarding NWA 4480:

Rumble D. and Irving A.J.
(2009) Dispersion of oxygen isotopic compositions among 42 Martian meteorites determined by laser fluorination:
Evidence for assimilation of (ancient) altered crust (abs#2293). Lunar Planet. Sci.
XL, Lunar Planetary Institute @ The Woodlands.

Irving A.J., Kuehner S.M., Korotev R.L. and Hupé G.M.
(2007a) Baby basaltic Shergottite NWA 4480:
An Eu-anomalous Martian magma related to “Lherzolitic” Shergottites (abs#5127). Meteorit. & Planet. Sci. 42, A73.

Connolly H.C. and 7 authors
(2007b) The Meteoritical Bulletin, No. 92, 2007
September. Meteorit. & Planet. Sci. 42, 1647-1694.

6.63 gram main mass of NWA 4480.
6.63 gram main mass of NWA 4480.
  13 gram uncut mass of NWA 4480.
13 gram uncut mass of NWA 4480.

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