Martian spherules

Martian spherules (also known as hematite spherules, blueberries, & Martian blueberries) are small spherules (roughly spherical pebbles) that are rich in an iron oxide (grey hematite, α-Fe2O3) and are found at Meridiani Planum (a large plain on Mars) in exceedingly large numbers.

  • Loose hematite spherules at Eagle Crater. Spherule diameters are 3-6 mm.
    Loose hematite spherules at Eagle Crater. Spherule diameters are 3-6 mm.
  • Close-up of sediment matrix with embedded hematite spherules at Eagle Crater. The central (partially embedded) spherule is 3.7 mm in diameter.
    Close-up of sediment matrix with embedded hematite spherules at Eagle Crater. The central (partially embedded) spherule is 3.7 mm in diameter.
  • Small, loose hematite spherules northwest of Victoria Crater. Spherule diameters are 1 - 2 mm.
    Small, loose hematite spherules northwest of Victoria Crater. Spherule diameters are 1 - 2 mm.

These spherules were discovered on the Martian day that NASA's Mars Exploration Rover Opportunity landed at Meridiani Planum. (At NASA's Mission Control building that was January 24, 2004.) They are grey but look bluish next to the ubiquitous rusty reds on Mars, and since the first spherules found in Eagle Crater were 3–6 mm in diameter, the Opportunity team quickly called them "blueberries".

Martian blueberries are either embedded or loose. That is, Martian blueberries are either embedded in the large body of sediments of Meridiani Planum, or they are loose blueberries that lie directly on outcrops of the sediments or lie on top soils spread over the Meridiani sediments.[1][2] The size of these spherules varies by location and elevation across the Meridiani Planum.[3][4][5]

Martian blueberries are rich in the iron oxide hematite, but determining how rich they are in this iron oxide has proven difficult.[6][7][8][9][10][4][11] (more below). The formation of blueberries required aqueous chemistry and involved flows of acidic, salty, liquid water over the Meridiani Planum and over two geological epochs.[12][9][13][14][15][16]

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  10. ^ Morris, R. V.; Klingelhöfer, G.; Schröder, C.; Rodionov, D. S.; Yen, A.; Ming, D. W.; De Souza, P. A.; Wdowiak, T.; Fleischer, I.; Gellert, R.; Bernhardt, B.; Bonnes, U.; Cohen, B. A.; Evlanov, E. N.; Foh, J.; Gütlich, P.; Kankeleit, E.; McCoy, T.; Mittlefehldt, D. W.; Renz, F.; Schmidt, M. E.; Zubkov, B.; Squyres, S. W.; Arvidson, R. E. (2006). "Mössbauer mineralogy of rock, soil, and dust at Meridiani Planum, Mars: Opportunity's journey across sulfate-rich outcrop, basaltic sand and dust, and hematite lag deposits". Journal of Geophysical Research: Planets. 111 (E12). Bibcode:2006JGRE..11112S15M. doi:10.1029/2006JE002791. hdl:1893/17161.
  11. ^ Olsen, Rif Miles (2022). "Searching Mass-Balance Analysis to Find the Composition of Martian Blueberries". Minerals. 12 (6): 777. Bibcode:2022Mine...12..777O. doi:10.3390/min12060777.
  12. ^ Hynek, Brian M. (2002). "Geologic setting and origin of Terra Meridiani hematite deposit on Mars". Journal of Geophysical Research. 107 (E10): 5088. Bibcode:2002JGRE..107.5088H. doi:10.1029/2002JE001891.
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