Asuka 881371 meteorite, Sør Rondane Mountains, Queen Maud Land, Eastern Antarctica, Antarcticai

Regional Level Types
Asuka 881371 meteorite	Meteorite Fall Location
Sør Rondane Mountains	Mountain Range
Queen Maud Land	Region
Eastern Antarctica	Region
Antarctica	Continent

Asuka 881371 [Angrite, volcanic]
Found 1988, 11.3 g (single round stone)

In the late 1980’s three small and quite similar meteoritic stones (LEW 87051, LEW 86010, Asuka 881371) were found in Antarctica. Asuka 881371 is the largest of these three stones and has received the most attention. Asuka 881371 is dominated by three minerals - variable Olivine (found as euhedral crystals and porphyritic clasts), prismatic Anorthitic Plagioclase, and intragranular Fassaitic Pyroxene. Kirschsteinite is the most important of the several minor minerals reported here. Asuka 881371 is described as an ophitic rock in which much of the Olivine has apparently been mixed into a preexistent melt. [Many of the Olivine crystals are zoned at their contact points with Pyroxene and other ground mass phases.] The presence of Olivine, Plagioclase, and Pyroxene is, of course, to be expected in almost any meteorite stone. The presence of Fassaite (Al-Ti-rich Pyroxene) and Kirschstienite are, however, reminders of a very unique achondritic meteorite — Angra dos Reis, a January 1868 fall. Angra Dos Reis, Asuka 881371, and several other Angrites have crystallization ages of ~4.56 billion years

Indeed, Asuka 881371 is now classified as an angrite. Angrites are a relatively rare type of basaltic achondrite with low alkali contents, high Ca/Al ratios, and a distinctive mineral assemblage with various Al-Ca-Ti-rich phases often including exsolved kirschsteinite. They appear to have originated on a relatively large and ancient homeworld perhaps as large as or even larger than Vesta, the original parent body of most HED meteorites (Howardites, Eucrites, Diogenites). While the similarities with different other angrites are striking — resemblances between Asuka 881371 and the smaller LEW 87051 are almost uncanny, the peculiarities of the Angrite prototype have raised a few wrinkles. Angra dos Reis is nearly monomineralic (93% Fassaite) and lacks several of the phases found in other Angrites. However, the shared oxygen isotopic ratios, the Mn/Fe ratios and REE abundance patterns seem to mark the Angrite Group as a tighter grouping than, say, the Vigrano-like Carbonaceous Chondrites or the Enstatite chondrites. Whether the angrites are indeed representatives of a single homeworld and whether that original parent body/bodies still exist(s) are questions yet to be resolved.

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References