出典:Wikipedia
出典:『Wikipedia』 (2011/01/06 13:58 UTC 版)
Angrite is a rare achondrite consisting mostly of the mineral augite with some olivine, anorthite and troilite. It is named for the Angra dos Reis meteorite. Angrites are basaltic rocks, often having porosity, with vesicle diameters of up to 2.5 cm. Angrites are the oldest igneous rocks, with crystallization ages of around 4.55 billion years. By comparing the reflectance spectra of the angrites to that of several main belt asteroids, two potential parent bodies have been identified: 289 Nenetta and 3819 Robinson. Other scientists have suggested that angrites could represent ejecta from Mercury.