Ureilite

Ureilite is a rare type of stony meteorite that has a unique mineralogical composition very different from that of other stony meteorites. This dark grey or brownish meteorite type is named after the town Novo Urei, Mordova Republic of Russia, where a meteorite of this type fell on 4 September 1886. Notable ureilites are the Novo Urei and the Goalpara, also named for the town in which it landed (Goalpara, Assam India). On 7 October 2008, tiny asteroid 2008 TC₃ entered the Earth's atmosphere and exploded an estimated 37 kilometers (23 mi) above the Nubian Desert in Sudan. Fragments of this asteroid were recovered the following December and were found to be ureilite.

Composition

A technical name for ureilite would be olivine-pigeonite achondrite. Ureilites are noted for containing microscopic nano-diamonds only a few microns in diameter. Compared to most other meteorites, ureilites tend to have a high percentage of carbon (up to 2% by weight) in the form of nano-diamonds and graphite. The diamonds are probably the result of high pressure shockwaves produced by collisions of the ureilite parent body with other asteroids. Ureilites can be divided into two subcategories: monomict and polymict. Monomict ureilites are coarse grained olivine with minor pyroxene traces. Polymict ureilites are a mixture of clasts of dissimilar composition.

Origin

Unknown. Some groups of meteorites come from a single object (ie. Mars, Moon, 4 Vesta), but there has been no parent body found as yet for the ureilites. It is probable that their origin is a C-type asteroid.

See Also

Meteorite classification