Asteroid composition varies based on the asteroid's origin. An asteroid can contain rock, metal, clay, silicate, nickel, iron and water. All asteroids are covered in regolith, which is a rocky rubble. Regolith is commonly called space dust.
There are four asteroid classes, based on their location and composition. C-type asteroids are located around the outer areas of the main asteroid belt. They are dark and contain carbon. S-type asteroids are made up primarily of stone and iron. They are located in the main asteroid belt's inner section. D-type asteroids, located near Jupiter, are dark and contain carbon. V-type asteroids, located between Jupiter's and Uranus' orbits, are composed of eruptive substances.