Northwest Africa 7325

Northwest Africa 7325, also known as NWA 7325 is the first meteorite believed to have originated from Mercury. Found in a marketplace in Erfoud, Morocco in April 2012,[1] the meteorite is composed of 35 fragments with a combined weight of approximately 345 grams (12.2 oz).[2] Investigation of the meteorite by Anthony Irving at the University of Washington determined that the meteorite's composition is consistent with that of Mercury as determined by the MESSENGER spacecraft.[2][3] Irving cautioned, however, that NWA 7325 could also have come from a smaller but Mercury-like body;[4] an alternative explanation offered is that NWA 7325 may be a primitive achondrite.[5] Notable for its green fusion crust and high-magnesium/low-iron composition,[6] NWA 7325 is estimated to be 4.56 billion years old and was likely ejected from Mercury on an Earth-intersecting trajectory by an impact.[4]

Northwest Africa 7325
A 2.810-gram (0.0991 oz) slice of Northwest Africa 7325 with green chromium diopside crystals. Photograph courtesy of Stefan Ralew for the Jared Collins Collection.
TypeAchondrite
CountryMorocco
RegionNorthwest Africa
Observed fallNo
Found date2012
TKW345 grams (12.2 oz)

A later study questioned the association with Mercury by comparing FTIR spectra obtained from the meteorite to astronomical results of the planet's surface, finding insufficient similarities to constrain the meteorite as Mercurian in origin.[7]

References
  1. Northwest Africa 7325. Meteoritical Bulletin Database. Lunar and Planetary Institute, Houston, Texas. Accessed 2013-03-30.
  2. Major, Jason. March 29, 2013. "Greenish rock may be meteorite from Mercury". NBC News. New York. Accessed 2013-03-30.
  3. Irving, A. J.; Kuehner, S. M.; Bunch, T. E.; Ziegler, K.; Chen, G.; Herd, C. D. K.; Conrey, R. M.; Ralew, S. (March 2013). "Ungrouped Mafic Achondrite Northwest Africa 7325: A Reduced, Iron-Poor Cumulate Olivine Gabbro from a Differentiated Planetary Parent Body" (PDF). Proc. 44th Lunar and Planetary Science Conference (2013). 1719: 2164. Bibcode:2013LPICo1719.2164I.
  4. Kramer, Miriam. March 29, 2013. "Green Meteorite May Be from Mercury, a First". Yahoo! News. Accessed 2013-03-30.
  5. Witze, Alexandra (June 13, 2013). "Mystery Meteorite: The case for (and against) a rock from Mercury". Science News. Retrieved 2014-05-17.
  6. Beatty, Kelly (February 1, 2013). "The First-Ever Meteorite from Mercury?". Sky & Telescope. Archived from the original on April 11, 2013. Retrieved 2014-05-17.
  7. Weber, I.; Morlok, A.; Bischoff, A.; Hiesinger, H.; Ward, D.; Joy, K. H.; Crowther, S. A.; Jastrzebski, N. D.; Gilmour, J. D.; Clay, P. L.; Wogelius, R. A.; Greenwood, R. C.; Franchi, I. A.; Münker, C. (2016). "Cosmochemical and spectroscopic properties of Northwest Africa 7325—A consortium study". Meteoritics & Planetary Science. 51 (1): 3–30. doi:10.1111/maps.12586.
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