E-type asteroid

They are thought to have originated from the highly reduced mantle of a differentiated asteroid.

Probably because they originated from the edge of a larger parent body rather than a core, E-types are all small, with only three (44 Nysa, 55 Pandora, 64 Angelina) having diameters above 50 kilometres and no others above 25 kilometers (the biggest three also orbit atypically far, c. 3 AU, from the Sun).

[4] The dispersal of most of that hypothetical E-Belt might have been caused by the outward migration of the gas giants of the Solar System according to simulations done under the Nice model – and these dispersed E-Belt asteroids might in turn have been the impactors of the Late Heavy Bombardment.

On September 5, 2008, ESA's robotic spaceprobe Rosetta visited the E-type asteroid 2867 Šteins.

[5] Spectral data from the spacecraft confirmed the asteroid was composed mainly of iron-poor minerals such as enstatite (magnesium-rich pyroxene), forsterite (magnesium-rich olivine) and feldspar.