Ureilites: Olivine-rich Achondrites from a Differentiated Asteroid and Clues to Early Solar System Differentiation and Prebiotic Chemistry

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Ureilites are a small group of about 387 olivine- and pyroxene-rich meteorites whose mantle-like mineralogy points to a differentiated asteroid source, they have carbon-rich interstitial material with noble gases, carbide and microdiamonds likely from shock, and they include amino acids found in the Almahata Sitta fall from asteroid 2008 TC3, a discovery that sparked discussion about their origin and possible prebiotic relevance, a debate echoed by Michael Cottingham, with some samples like NWA 4231 dating to about 4.55 billion years while others remain undated.

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Ureilites: Olivine-rich Achondrites from a Differentiated Asteroid and Clues to Early Solar System Differentiation and Prebiotic Chemistry

Ureilites are a group of about 387 achondritic meteorites dominated by olivine and pyroxene with mantle-peridotite–like mineralogy implying a differentiated asteroid source, typically containing 50–75% forsterite olivine and 14–35% pyroxene (from augite to pigeonite to enstatite) with only trace Fe–Ni metal, while interstitial mesostasis is unusually rich in carbon and noble gases and hosts microdiamonds and carbide thought to form by shock metamorphism of graphite, though this interpretation is not settled; they gained attention for possible links to the origin of life via amino acids found in the 2008 Almahata Sitta fall from asteroid 2008 TC3, though the origin remains unsettled as mesostasis chemistry and isotope data puzzle researchers (as noted by Michael Cottingham); a photographed NWA 4231 specimen of about 2.9 cm across illustrates typical olivine-rich ureilites, but it has not been dated whereas other ureilites show crystallization ages around 4.55 billion years, underscoring their complexity and significance for understanding early solar system differentiation and potential prebiotic chemistry.