Hermiominerals

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NWA 7325 is a unique meteorite. Credit: Stefan Ralew / sr-meteorites.de.{{fairuse}}

"NWA 7325 is actually a group of 35 meteorite samples discovered in 2012 in Morocco. They are ancient, [...] dating the rocks to an age of about 4.56 billion years."[1]

"NWA 7325 has a lower magnetic intensity — the magnetism passed from a cosmic body's magnetic field into a rock — than any other rock yet found. Data sent back from NASA's Messenger spacecraft currently in orbit around Mercury shows that the planet's low magnetism closely resembles that found in NWA 7325."[2]

"NWA 7325 has olivine in it that is insanely magnesium-rich. Iron and magnesium are two elements that are almost always found together in rocks; the ions they make have the same size and charge so they happily occupy the same positions in crystal lattices. It's weird to have a rock that is so dominantly magnesium-rich. Mercury's surface rocks are known (thanks to MESSENGER) to be unusually low in iron."[3]

"NWA 7325's oxygen isotope ratios do not match any known meteorites from any other planet-size body. In fact, they're not particularly similar to much of anything that we've measured oxygen isotope ratios for."[3]

"The ratios of Al/Si (0.224) and Mg/Si (0.332) plus the very low Fe content of NWA 7325 are consistent with the compositions of surface rocks on Mercury [6], but the Ca/Si ratio (0.582) is far too high. However, since NWA 7325 is evidently a plagioclase cumulate (and presumably excavated from depth), it may not match surface rocks on its parent body. The abundance of diopside rather than enstatite might be consistent with some earlier spectral observations of Mercury [7]."[4]

"[I]t's about 23 times harder to get a rock from Mercury to Earth than it is from Mars to Earth. Given that we've got more than 70 known Mars meteorites in our collections, that means we ought to have found 3 (give or take a couple) Mercury meteorites by now."[3]

Forsterites[edit | edit source]

This is a visual image of a forsterite crystal. Credit: Azuncha.{{free media}}
Forsterite is the big tabular and colorless crystal on sanidine (little colorless crystals). Credit: Fred Kruijen.{{free media}}

Mg2SiO4 is the formula for forsterite, with 28.6 at % magnesium.[5]

Forsterite is a member of the olivine group of minerals.[5]

See also[edit | edit source]

References[edit | edit source]

  1. Miriam Kramer (March 28, 2013). "Green Meteorite May Be from Mercury, a First". SPACE.com. Retrieved 2013-03-31.
  2. Anthony Irving (March 28, 2013). "Green Meteorite May Be from Mercury, a First". SPACE.com. Retrieved 2013-03-31.
  3. 3.0 3.1 3.2 Emily Lakdawalla (March 21, 2013). LPSC 2013: Do we have a meteorite from Mercury?. The Planetary Society. http://www.planetary.org/blogs/emily-lakdawalla/2013/03211549-lpsc-hermean-meteorite.html. Retrieved 2013-03-22. 
  4. A. J. Irving; S. M. Kuehner; T. E. Bunch; K. Ziegler; G. Chen; C. D. K. Herd; R. M. Conrey; S. Ralew (March 20, 2013). Ungrouped Mafic Achondrite Northwest Africa 7325: A Reduced, Iron-poor Cumulative Olivine Gabbro from a Differentiated Planetary Parent Body. Lunar and Planetary Science Conference. http://www.lpi.usra.edu/meetings/lpsc2013/pdf/2164.pdf. Retrieved 2013-03-22. 
  5. 5.0 5.1 Willard Lincoln Roberts; George Robert Rapp Jr.; Julius Weber (1974). Encyclopedia of Minerals. New York, New York, USA: Van Nostrand Reinhold Company. pp. 693. ISBN 0-442-26820-3. 

External links[edit | edit source]

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