Silicaceous Type Asteroid
Image from John M Dollan
Silicaceous Asteroids have high albedoes (from 15% to 25%) are slightly red in colour and contain metallic elements. Silicaceous asteroids are mainly metallic iron and magnesium-silicates in composition. Quite common, these bodies are sometimes mined, but more often used as bases or refineries for other materials. Many times these are fragments from larger bodies, even to the point of bing little more than piles of "rubble", loose aggregates of material that have been drawn back together by gravity after the initial object was broken up.
As a solar system forms, a population of asteroids might form close enough to the young and active sun so that they become differentiated bodies. These Silicaceous asteroids are heated sufficiently by the electromagnetic currents so that minerals will become separated, much like the process experienced by larger worlds due to their internal heating. As the sun begins to stabilize and cool down, what is left is a rocky body that typically has an olivine crust surrounding a nickel-iron alloy core; a fully differentiated asteroid may become a member of the Vesta- or V-subtype.