Official Meteoritical Bulletin entry for Northwest Africa 5789:
Northwest Africa 5789 Morocco 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 Fa15.6–16.6, FeO/MnO = 45.2–49.4;
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. http://www.lpi.usra.edu/meetings/lpsc2012/pdf/2510.pdf
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. http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1813.pdf
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. http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1547.pdf