Millbillillie meteorite, Wiluna, Wiluna Shire, Western Australia, Australiai

Regional Level Types
Millbillillie meteorite	Meteorite Fall Location
Wiluna	Town
Wiluna Shire	Shire
Western Australia	State
Australia	Country

Eucrite meteorite, monomict breccia
Fall October 1960; ~330 kg


Two station workers in October 1960 were opening a gate along a track between Millbillillie and Jundee Stations, when they witnessed a fireball in the sky, landing to the north in a spinifex covered plain. No search was conducted at the time but in 1970 or 1971, a friend or relative of one of the men was told the story and went searching. Two stones were found, and since then many more fragments by locals. The Millbillillie eucrite now stands alone as the only eucrite recovered with a mass > 100 kg. Indeed, Millbillillie is by far the most massive meteorite of any of those recovered meteorites (most Howardites, Eucrites, and Diogenites) which are believed to be fragments of the asteroid Vesta.

It is classified as an Achondritic Eucrite meteorite, light weight (think pumice) with no iron and being composed of silicate minerals, being granulitic fragmental breccias, melted material and glassy veins. Large parts are composed of anorthite (a plagioclase feldspar) and pigeonite ( a clinopyroxene). Minor phases such as chromite, troilite, and ilmenite are also found. Many of the specimens are covered with a black glassy fusion crust and sometimes desert soil. They show the best multiple lipping and flowlines of any meteorite.

While the primary constituents are various pyroxenes and plagioclase of only moderately varying composition, portions of Millbillillie were subject to a series of pummeling impacts which have left behind a melange of coarse and fine crystals, comminuted clasts, and glass with an unusually diverse set of textures and histories. Thermal annealing after brecciation has partially homogenized the severely brecciated constituents.

Most planetary scientists and meteoriticists believe that most - but not all - of the HED group of meteorites originated from the Vesta Asteroid, the second largest body in the Asteroid Belt at 500 kilometres across. The Millbillillie lithology was itself apparently formed ~4.54-4.55 billion years ago with traces of several impacts occurring during the next billion years. (Plagioclase, zircon, and small Ca-rich phosphates have all been used to establish this still emerging chronology)

See also Wiluna meteorite locality.

Other Regions, Features and Areas containing this locality

References