* Rock: Asteroids are primarily composed of rock, which can be either silicate or carbonaceous. Silicate rocks are made up of silicon, oxygen, and other elements, while carbonaceous rocks contain carbon and hydrogen.

* Metal: Asteroids can also contain metal, such as iron, nickel, and copper. Metallic asteroids are often found in the inner solar system, while silicate and carbonaceous asteroids are more common in the outer solar system.

* Ice: Some asteroids contain ice, which is made up of water molecules. Icy asteroids are often found in the outer solar system, where temperatures are cold enough for ice to remain solid.

* Organic molecules: Asteroids can also contain organic molecules, which are molecules that contain carbon. Organic molecules are the building blocks of life, and they are thought to have been present in the early solar system when life first began.

A sample returned to Earth from asteroid Itokawa revealed that it is composed of a variety of materials, including:

* Silicate rocks

* Carbonaceous rocks

* Metal

* Ice

* Organic molecules

This sample is a valuable resource for scientists who are studying the early solar system and the origins of life.