Northwest Africa 5789 Martian Meteorite

Original fragment of NWA 5789.
Original fragment of NWA 5789.

Official Meteoritical Bulletin entry for Northwest Africa 5789:

Northwest Africa 5789
     Find (found January 2009, purchased May 2009)
     Achnodrite (Martian, olivine-phyric shergottite)

History: A small chip from one of three crusted stones found together in Morocco was sent from a dealer in Erfoud to Greg Hupé, and subjected to preliminary testing at UWS. Subsequently the stones were purchased in May 2009 by Stefan Ralew and Martin Altmann. [Moroccan dealer had no intentions of selling to Hupé, just used for confirmation].
Physical characteristics: A 49 g partly crusted stone, naturally broken into three pieces that fit together (Fig. 4a). The interior consists mainly of pale yellowgreen olivine macrocrysts in a light brownish-gray, finer-grained matrix (Fig. 4b). No maskelynite is evident. Several exterior sides are coated by glossy black fusion crust, which contains embedded rounded quartz grains.
Petrography: (A. Irving and S. Kuehner, UWS; J. Gross, A. Treiman, K. Robinson, LPI) Small (up to 1 mm), zoned olivine macrocrysts (in multi-crystalline clusters) with narrow ferroan rims are set in a finer grained groundmass composed mainly of prismatic low-Ca pyroxene grains with accessory olivine, chromite, pyrrhotite, and small regions of mesostasis (approximately 2 vol%) composed of subparallel, laminar to sheaf-like intergrowths of pigeonite, intermediate plagioclase, silica, ilmenite, and merrillite. The pyroxenes exhibit chaotic compositional zoning, with low-Ca pyroxene cores, regions of pigeonite and augite, and narrow ferropigeonite rims.
Geochemistry: Olivine macrocrysts (cores Fa15.616.6, FeO/MnO = 45.249.4; mantle Fa22.6, FeO/MnO = 47.6; rim Fa45.4, FeO/MnO = 58.9), matrix olivine (Fa47.3, FeO/Mno = 61.1), low-Ca pyroxene (cores as magnesian as Fs17.1Wo1.6, FeO/MnO = 30.9), pigeonite
Classification: Achondrite (Martian, olivine-phyric shergottite). This specimen has mineralogical and bulk compositional similarities to Yamato 980459/980497, but differs from those stones in having very little mesostasis.
Specimens: A total of 9.8 g, two polished thin sections and a polished mount are on deposit at UWS; a further 5.6 g of material is held by A. Treiman (LPI) and another 3.3 g at UAb. The remaining material is held by anonymous collectors and institutions.

Scientific abstracts and news regarding NWA 5789:

Irving A.J., Kuehner S.M., Tanaka R., Herd C.D.K., Chen G. and Lapan T.J.
(2012b) The Tissint depleted permafic olivine-phyric Shergottite:
Petrologic, elemental and isotopic characterization of a recent Martian Fall in Morocco (abs#2510).
Lunar Planet. Sci. XLIII,
Lunar Planetary Institute @ The Woodlands.

Matzen A.K., Beckett J.R., Baker M.B. and Stopler E.M.
(2011) Fe2+-Mg partioning between olivine and Martian basaltic melts (abs#5528).
Meteorit. & Planet. Sci. 46, A150.

Franz H.B., Farquhar J. and Irving A.J.
(2010) Acid volatile sulfur isotopic composition of seven Shergottites from Northwest Africa (abs#2341).
Lunar Planet. Sci. XLI.
Lunar Planetary Institute Houston.

Gross Juliane, Treiman A.H., Filiberto J. and Herd C.D.K.
(2010) Primitive olivine-phyric Shergottite NWA 5789: Petrology, mineral chemistry and cooling
history imply a magma similar to Yamato-980459 (abs#1813).
Lunar Planet. Sci. XLI, 287-288.
Lunar Planetary Institute, Houston.

V.H. Hoffmann1,2, M. Funaki3, M. Torii.

Irving A.J., Kuehner S.M., Herd C.D.K., Gellissen M., Korotev R.L., Putchel I., Walker R.J., Lapan T.J. and Rumble D.
(2010b) Petrologic, elemental and multi-isotopic characterization of permafic olivine-phyric Shergottite
Northwest Africa 5789: A primitive magma derived from depleted Martian mantle (abs#1547).
Lunar Planet. Sci. XLI,
Lunar Planetary Institute @ The Woodlands.

Weisberg M.K. et al.
(2010a) Met. Bull #97. Meteorit. & Planet. Sci. 45, 449-493.

One of three fragments from NWA 5789 - View 1.
One of three fragments from NWA 5789 - View 1.
  One of three fragments from NWA 5789 - View 2.
One of three fragments from NWA 5789 - View 2.

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