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Yamato 81020 meteorite (Y-81020), Queen Fabiola Mts (Yamato Mts), Queen Maud Land (Dronning Maud Land), Eastern Antarctica, Antarctica

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Latitude & Longitude (WGS84): 71° 30' South , 35° 40' East
Latitude & Longitude (decimal): -71.50000,35.66667
Other regions containing this locality:Antarctic Meteorites
Non-native locality type:Meteorite
Meteorite Class:CO3.0 chondrite meteorite
Meteoritical Society Class: CO3.0
Metbull:View entry in Meteoritical Bulletin Database
Köppen climate type:EF : Ice cap climate

Carbonaceous Chondrite (CO3.0; S1)
Find, 1981; 270 g

Yamato 81020 (Y-81020) is a very small stone rich in small chondrules and inclusions embedded in a very fine-grained matrix. While it was soon recognized as a somewhat primitive CO (Ornans-like) carbonaceous chondrite [See Graham, et al., 1985], early interest in the meteorite was focused on the small spinel-rich refractory inclusions within the meteorite and very little of the readily available literature references the small olivine and pyroxene chondrules or tiny silicate grains within the matrix which actually constitute most of the meteorite. That is beginning to change because it now clear that Y-81020 is one of the very few type 3.0 CO meteorites and is not only rich in relatively unaltered spinels and other high temperature condensates from the early solar nebula, but its chondrules, amoeboidal olivine-rich aggregates, and matrix silicates are an isotopically diverse mixture from a very ancient physical regime within the early solar nebula — a regime that is sparsely represented even within the carbonaceous chondrites themselves.

As of July 2014 all 498 known CO chondrites were classified as type CO3 chondrites, but only 64 CO chondrites have been classified as belonging to one of the subtypes between CO3.0 and CO3.8. Yamato 81020 is one of the 7 known CO3.0 meteorites. Four of the CO3.0s are Northwest Africa meteorites and represent an unknown number of separate falls (1-4?) as the main masses of 3 of them are held by the same individual. As (probably) one of only 4 or 5 CO3.0 meteorites, Y-81020 is a rare meteorite indeed.

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16 valid minerals.

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Graham, A. L., Yanai, K., Kojima, H. & Ikadai, S. (1985) Yamato 81020 and Yamato 82042; Two New Carbonaceous Chondrites from Antarctica: Meteoritics 20 (4): 654-655. (Dec 1985).

Kojima, T., Yada, S. & Tomeoka, K. (1995) Ca-Al-rich inclusions in three Antarctic CO3 chondrites, Yamato-81020 Yamato-82050 and Yamato-790992: Record of low temperature alteration. Proc. NIPR Symposium. Antarct. Meteorites 8: 79-96. (May 1995).

Brearley, A. J. & Jones, R. H. (1998) Chondritic Meteorites: IN: Planetary Materials (Papike, J.J. [Ed.]), Chapter 3, 398 pages: Mineralogical Society of America: Washington, DC, USA.

Grady, M. M. (2000). Catalogue of Meteorites (5/e). Cambridge University Press: Cambridge; New York; Oakleigh; Madrid; Cape Town. 689 pages.

Yurimoto, H., Rubin, A. E., Itoh, S. & Wasson, J. T. (2001) Non-Stoichiometric Al-rich Spinel in an Ultra-Refractory Inclusion from CO Chondrite (abstract): Lunar and Planetary Science Conference XXXII, abstract #1557. (Mar 2001)

Itoh, S., Rubin, A. E., Kojima, H., Wasson, J. T. & Yurimoto, H. (2003) Amoeboid Olivine Aggregates and AOA-bearing Chondrule from Y-81020 CO3.0 Chondrite: Distribution of Oxygen and Magnesium Isotopes (abstract): Lunar and Planetary Science Conference XXXIII, abstract no.1490. (Mar 2003).

Komatsu, M., Krot, A. N., Miyamoto, M. & Keil, K. (2005) EBSD Study of Amoeboid Olivine Aggregates with Low-Ca Pyroxenes in the Y-81020 CO3.0 Chondrite (abstract): Annual Lunar and Planetary Science Conference XXXVI, abstract #1573. (March 2005).

Tenner, T. J., Ushikubo, T., Kurahashi, E., Kita, N. T. & Nagahara, H. (2011) Oxygen Isotopic Measurements of Phenocrysts in Chondrules from the Primitive Carbonaceous Chondrite Yamato 81020: Evidence for Two Distinct Oxygen Isotope Reservoir. Lunar and Planetary Science Conference XLII. LPI Contribution #1608: p.1426. (March 2011).

Krot, A. N., Doyle, P. & Nagashima, K. (2013) Secondary Fayalite, Hedenbergite, and Magnetite in the CO3.0-3.1 Carbonaceous Chondrites Y-81020, EET 90043, and MAC 88107: Lunar and Planetary Science Conference XLIV. LPI Contribution #1719: p.1754. (Mar 2013).

Grady, M. M., Pratesi, G. & Moggi Cecchi, V. (2015) Atlas of Meteorites. Cambridge University Press: Cambridge, United Kingdom. 373 pages.

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