Yamato 000593
Yamato 000593 meteorite—13.7 kg (30 lb). The cube is 1 cm (0.39 in) (NASA; 2012).
Type	Achondrite
Structural classification	Igneous[1]
Class	Martian meteorite[2]
Group	Nakhlite[2]
Composition	pyroxene 85%[1] olivine 10%
Shock stage	S3[1]
Weathering grade	B[3]
Country	Antarctica[2]
Region	Yamato Glacier[2]
Coordinates	71°30′S35°40′E / 71.500°S 35.667°E /-71.500; 35.667[3][4]
Observed fall	No
Fall date	50,000 years ago[2]
Found date	2000[2]
TKW	13.7 kg (30 lb)[2]
Related media on Wikimedia Commons

Yamato 000593 (orY000593) is thesecond largestmeteorite fromMars found onEarth.^[2][5][6] Studies suggest theMartian meteorite was formed about 1.3 billion years ago from alava flow onMars.^[7] Animpact occurred on Mars about 11 million years ago^[7] and ejected the meteorite from the Martian surface intospace. The meteorite landed on Earth inAntarctica about 50,000 years ago. Themass of the meteorite is 13.7 kg (30 lb) and has been found to contain evidence of pastwater alteration.^[2][5][6][8]

At a microscopic level, spheres are found in the meteorite rich incarbon compared to surrounding areas lacking such spheres. The carbon-rich spheres and the observed micro-tunnels may have been formed bybiotic activity, according to NASA scientists.^[2][5][6]

The 41stJapanese Antarctic Research Expedition (JARE) found the meteorite in late December 2000 on theYamato Glacier in theQueen Fabiola Mountains,Antarctica.^[2][9]

The mass of the meteorite is 13.7 kg (30 lb).^[2] It is an unbrecciated cumulusigneous rock consisting predominantly of elongatedaugite crystals—asolid solution in thepyroxene group.^[9] Japanese scientists from the National Institute of Polar Research reported in 2003 that the meteorite containsiddingsite, which forms from the weathering of basalt in the presence of liquid water.^[9] In addition, NASA researchers reported in February 2014 that they also found carbon-rich spheres encased in multiple layers of iddingsite, as well as microtubular features emanating from iddingsite veins displaying curved, undulating shapes consistent with bio-alteration textures that have been observed in terrestrial basaltic glass.^[2] However, the scientific consensus is that "morphology alone cannot be used unambiguously as a tool for primitive life detection."^[10][11][12] Interpretation of morphology is notoriously subjective, and its use alone has led to numerous errors of interpretation.^[10] According to the NASA team, the presence of carbon and lack of corresponding cations is consistent with the occurrence oforganic matter embedded in iddingsite.^[5] The NASA researchers indicated thatmass spectrometry may provide deeper insight into the nature of the carbon, and could distinguish between abiotic and biologic carbon incorporation and alteration.^[5]

The Martian meteorite is anigneous rock classified as anachondrite type of thenakhlite group.^[2][1]

Microscopic image of Y000593 meteorite showsiddingsite as evidence ofwater alteration. It displays microtunnels that may have been formed by biotic activity (February 27, 2014).

Y000593 has areas with spheres (red) that have twice thecarbon as areas without spheres (blue) (February 27, 2014).

Microscopic image of theNakhla-like surface of meteorite Yamato 000593 (November 2009).

• Yamato meteorite (PDF) The Astromaterials Acquisition and Curation Office, NASA.

• Achondrite meteorites
• Astrobiology
• Martian meteorites
• Meteorites found in Antarctica
• Natural history of Antarctica

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