<P> The current belt consists primarily of three categories of asteroids: C - type or carbonaceous asteroids, S - type or silicate asteroids, and M - type or metallic asteroids . </P> <P> Carbonaceous asteroids, as their name suggests, are carbon - rich . They dominate the asteroid belt's outer regions . Together they comprise over 75% of the visible asteroids . They are redder in hue than the other asteroids and have a very low albedo . Their surface composition is similar to carbonaceous chondrite meteorites . Chemically, their spectra match the primordial composition of the early Solar System, with only the lighter elements and volatiles removed . </P> <P> S - type (silicate - rich) asteroids are more common toward the inner region of the belt, within 2.5 AU of the Sun . The spectra of their surfaces reveal the presence of silicates and some metal, but no significant carbonaceous compounds . This indicates that their materials have been significantly modified from their primordial composition, probably through melting and reformation . They have a relatively high albedo and form about 17% of the total asteroid population . </P> <P> M - type (metal - rich) asteroids form about 10% of the total population; their spectra resemble that of iron - nickel . Some are believed to have formed from the metallic cores of differentiated progenitor bodies that were disrupted through collision . However, there are also some silicate compounds that can produce a similar appearance . For example, the large M - type asteroid 22 Kalliope does not appear to be primarily composed of metal . Within the asteroid belt, the number distribution of M - type asteroids peaks at a semi-major axis of about 2.7 AU . It is not yet clear whether all M - types are compositionally similar, or whether it is a label for several varieties which do not fit neatly into the main C and S classes . </P>

Where are s-type asteroids typically found in the solar system ​