B-type asteroid

They are thought to be primitive, volatile-rich remnants from the early Solar System.

Generally similar to the C-type objects, but differing in that the ultraviolet absorption below 0.5 μm is small or absent, and the spectrum is rather slightly bluish than reddish.

Spectroscopy of B-class objects suggests major surface constituents of anhydrous silicates, hydrated clay minerals, organic polymers, magnetite, and sulfides.

The closest matches to B-class asteroids have been obtained on carbonaceous chondrite meteorites that have been gently heated in the laboratory.

[3][4] Some of these objects display indications of aqueous alteration in the past, and they may have incorporated significant amounts of water ice.