C-type asteroid

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C-type (carbonaceous /ˌkɑːrbəˈneɪʃəs/) asteroids are the most common variety, forming around 75% of known asteroids.^[1] They are volatile-rich and distinguished by a very low albedo because their composition includes a large amount of carbon, in addition to rocks and minerals. They have an average density of about 1.7 g/cm³.

They lie most often at the outer edge of the asteroid belt, 3.5 au (520 million km; 330 million mi) from the Sun, where 80% of the asteroids are of this type, whereas only 40% of asteroids at 2 au (300 million km; 190 million mi) from the Sun are C-type.^[2] The proportion of C-types may actually be greater than this, since C-types are much darker (and hence less detectable) than most other asteroid types, except for D-types and others that lie mostly at the extreme outer edge of the asteroid belt.