Yamato 81020 meteorite, Queen Fabiola Mts, Queen Maud Land, Eastern Antarctica, Antarcticai

Regional Level Types
Yamato 81020 meteorite	Meteorite Fall Location
Queen Fabiola Mts	Mountain Range
Queen Maud Land	Region
Eastern Antarctica	Region
Antarctica	Continent

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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References