Composition would be strikingly different. Elements which are rare in the Earth's crust (and therefore, expensive) are rare because during the formation of the

Composition would be strikingly different. Elements which are rare in the Earth's crust (and therefore, expensive) are rare because during the formation of the Earth they sank under gravity and now reside near the core of the planet. Chondritic asteroids, on the other hand, are left over from the primordial solar system and have the original relative abundances of rare earth materials. Hence the interest as a source of industrial resources.